Advancing the science of gardening and other stuff since 2009
Author: John Porter
John Porter is a horticulturalist located in Omaha, NE. He is a former extension educator with UNL Extension and county agent with WVU extension. In addition to using his horticulture and extension skills in his home garden, he is a sometimes garden writer and lecturer, a trial judge for All-America Selections, and mentor for local school horticulture and agriculture programs.
It may seem odd to sing the praises of a weird, sometimes gross, looking phenomenon that sometimes freaks gardeners out, but every summer I love educating gardeners about the fascinating lives of slime molds. Here in Nebraska we often get calls about “this weird thing that’s all over my mulch” after a rainy period in the summer and whether or not it will 1) hurt their plants, 2) poison them, or 3) some other horrible outcome they’ve dreamed up. But the fact is, not only are slime molds harmless they’re also quite fascinating. In fact, I’ve often thought if I ever had the right terrarium setup, I’d love to have a pet slime mold. No joke.
What is a slime mold?
Basically speaking, slime molds are a group of eukaryotic organisms similar to amoebae that feed on microorganisms and do some pretty amazing things for simple-celled organisms. They can often be found in soils, forests, especially wetter ones, where they live on the microorganisms that are breaking down fallen logs and detritus on the forest floor. In gardens, you’ll find them in areas with heavy, woody mulches or high organic matter. (They also live in rain gutters if they’re full of leaves and also air conditioner units with poor drainage, FYI.) Most of the calls that we receive at the extension office are from suddenly finding slime mold in woodchip mulch. Usually after a large or extended rain event during the summer, and usually in thickly layered (several inches) mulch.
When food (microorganisms) is abundant, the majority of a slime molds, at least the ones in the “cellular slime mold” category live most of their lifecycle is as a single cell, imperceptible to humans. But when food becomes scarce is when the fun begins. In mulch, this can happen when the weather conditions (wet and hot) favor a slime mold population boom thanks to sexual reproduction and they eat themselves out of house and home. When that happens, the individual cells join together as a single body (one big cell blob with multiple nuclei), forming a visible and for many disconcerting presence in the landscape. Many of them look like actual slime and several look like webbed networks or neural structures.
Slime mold on mulch | Jody Green, UNL Extension @JodyBugsMeUNL
The most fun thing about slime mold, though, and the thing that I love about them is that THEY MOVE! Yep, you heard that right. These single-celled organisms, that stream together to form a single body, can chemically sense the presence of food in the nearby environment and will change shape (together) to move toward the food. And they’ll follow the food wherever it is – on the ground, up on a plant, into the canopy of a tree, etc. Scientists have demonstrated this by having slime molds solve mazes or even create designs, like the Tokyo subway system, in vitro. The trail of slime that it leaves in its path even relays a chemical signal that it uses to “remember” where it has been so it doesn’t backtrack or go the wrong direction.
Several of our concerned callers call because a slime mold has moved up onto one of their plants and they want to know if 1) it will kill their plant and 2) if it is toxic. Neither of which is the case. But most of our calls happen when our most common slime mold in the area moves onto its next phase of life – spore production.
You see, when environmental conditions change or the slime mold finds a good supply of food it is time to settle down for some good old-fashioned asexual reproduction. The shape and texture of the slime mold changes, usually becoming more pronounced and dryer looking as it produces sporangia that produces spores.
Callers often describe what looks like dog vomit in their landscape, and that’s where our common slime mold gets its name – the Dog Vomit Slime Mold (Fuligo septica).
Shortly after this phase, the collective body of the slime mold will dissipate. Spores will turn into new single-celled organisms that will repeat the process over again.
Can it be stopped or controlled?
First of all, why would you want to stop this fascinating phenomenon in your garden? (I’m kidding). Really, there’s nothing you can do as a control and there really isn’t a need to do so. As I stated earlier, slime molds do no harm to plants and aren’t dangerous for people or pets. If you just don’t like the look of it, you can reduce the likelihood of it popping up in your landscape by reducing the thickness of woodchip mulch (don’t let my GP colleague Linda hear me say that) or reduce irrigation if it is occurring outside of larger rain events.
Otherwise, just enjoy your pet! It won’t hang around for long. The visible, fascinating life of a slime mold is fleeting but exciting. Next time you see a slime mold, check it out! And keep an eye on it to see if it moves or if it progresses through its life cycle – maybe you’ll just develop an appreciation for them, too. And I’m not joking about pet slime molds, someone even wrote a guide to dog vomit slime mold pet care!
Auntie Mame was on to something when she told her orphaned nephew Patrick to “Haul out the Holly, Put up the Tree Before My Spirit Falls Again” (I just sang this in a concert with my community chorus. I’ve been hauling out the holly since August, so I’m done.)
Plants play a big part in our holiday traditions this time of year. When it comes to decorating for the holidays, needless to say I prefer a simpler, natural approach. The best inspiration — and materials — come from nature and sometimes from your very own landscape. It is no secret that the celebration of Christmas was timed by early church leaders to coincide with other ancient winter festivals that predate Christianity. It made it easy to get everyone to join in the celebrations.
Saturnalia was a Roman festival that celebrated Saturn, the
deity of agriculture, and the harvest. Yule was a 12-day midwinter festival
celebrated by Germanic pagans into which Pope Julius I inserted Christmas in AD
336 (there was no celebration of Christmas until then), giving rise to the
12-day Christmastide festival (or Yuletide, depending on where you are). The
celebration of the winter solstice is also of pagan origin, a celebration of
the darkest, or shortest, day of the year (in the Northern Hemisphere) and the
rebirth of the sun.
Many of these festivals included the bringing of evergreens
and natural elements indoors to celebrate the connection between humans and
nature. They were a sign that life would return after the cold, harsh winter.
And also a way to bring a little cheer indoors to brighten up the home during
the cold, dreary winter.
If you look at many of the more traditional elements of Christmas, you’ll notice their connection with nature, and specifically plants — evergreens, holly, amaryllis, poinsettias and more. Of course, the star of the show is the Christmas tree. Christmas trees as we know them didn’t debut until the 16th century in Germany.
A prickly holiday tradition
I’ve written about several holiday plant traditions over the years, each a different way to look at a plant that or plants that bring tradition and cheer into the home. Perhaps the most popular of these articles is about one of the most recent additions to the holiday plant family – cacti. The interest in this holiday plant is surging thanks to the interest in houseplants at the moment. This is making an issue I pointed out several years ago in the article A Cactus by Any Other Name: A Case of Mistaken Holiday Cactus Identity about the mis-naming of cacti even more important. There’s a Christmas cactus, but there’s also a Thanksgiving cactus (and an Easter one, too).
Thanks to years of marketing and selling Thanksgiving cacti as Christmas cacti (since they bloom early enough for the Christmas shopping season and actual Christmas cactus bloom closer to Christmas), many people confuse the two. This isn’t a big issue for the casual holiday plant shopper, but for those that “collect” the plants it can be an issue trying to sort out which is which. For example, someone recently posted in a local plant group that they were looking for a Christmas cactus. Half the responses were telling them where they could buy a Thanksgiving (more commonly called Zygo cactus after the zygomorphous shape of the flower) cactus and the other half were asking if they meant that they wanted a true Christmas cactus or a Thanksgiving cactus.
As romantic as poop on a stick
As holiday plant traditions go, the hanging of mistletoe has to be both the most interesting and weirdest. As tradition goes, if two people meet beneath the mistletoe they’re supposed to kiss. How did kissing become associated with a toxic plant that parasitizes trees and whose name translated from the Anglo-Saxon means “poop on a stick” from the fact that the seeds are spread by bird droppings?
Mistletoe: the romantic parasite (Source: Wikimedia commons)
As I shared in The Myth, the Legend, the Parasite: Romance, Lore, and Science beneath the Mistletoe, Norse legend has it that the goddess Frigga (Frig, or Fricka) made everything on earth promise to not hurt her beloved son Baldr, but she forgot to ask mistletoe since it was so small and innocent looking. Baldur’s brother, the trickster Loki (you know, the one in all the movies these days) made a spear of mistletoe and that ended up killing Baldr. The white berries of mistletoe represent Frigga’s tears, and she decreed that the plant should represent love and that no harm should befall anyone standing below it. And there you have it.
The flower that’s really just a bunch of overachieving
leaves
Most recently, I shared a bit of history and lore around poinsettias, that common but prissy holiday plant that most people can’t keep alive more than a few weeks. I mean, the original Aztec name for the plant, cuetlaxochitl (ket-la-sho-she), can be translated as meaning “flower that withers” or “mortal flower that perishes like all that is pure”, so the reputation fits. The actual flowers of the plant are the ugly little greenish-yellow bits in the center, which are highlighted by leaves, called bracts, that change colors to bright red (and more colors now) as the flowers develop.
The flower and the bright red represented a gift from the gods for the sacrifices that the Aztecs would make to them. You can read a bit about the history, and how to save them and get them to rebloom from year to year (if you dare) in my festive little ditty Poinsettias: from ditch weed to holiday super star (history, lore, and how to get those d@!% things to rebloom next year). Of course, there’s been recent discussion on how the story of the poinsettia is similar to the pagan traditions associated with Christmas – a plant tradition of the Aztecs was changed as a way to fit with the Christmas story and work as a conversion tool. It is good to know a bit about the original tradition of the plant to understand its importance throughout history.
Haul out the holly….and the magnolia….and the
rhododendron…..
Holiday plant traditions don’t stop at those finicky plants
we grow in greenhouses- the original traditions of Solstice and Yule consisted
of bringing in all different types of plants for the season. Sometimes you have
to look no farther than your yard to find natural elements fit for a holiday
celebration. If you have evergreen trees or shrubs in your landscape, they can
easily be incorporated into holiday arrangements indoors or out.
While you can readily purchase live Christmas greenery at
many retailers and markets (except for this year, with all the supply issues
going on), what you can harvest from your own yard or nearby woods (where permissible)
will be much fresher and last much longer. Remember that harvesting branches
from your own trees and shrubs is actually pruning them, so you can kill two
birds with one stone.
Both white and Virginia pine make excellent decorating choices as they are long-lived and retain their needles well. Junipers, cedars and firs all have interesting foliage and wonderful evergreen scents. Junipers can sometimes be found with berries and cedars sometimes have tiny cones. Spruce is a great choice for wreaths, as it is bristly and holds its shape.
Decorating doesn’t have to be left to the needled
evergreens, though. Holly is a classic choice, but mountain laurel,
rhododendron, boxwood and magnolia and many others can provide beauty and
elegance in holiday displays.
You don’t even need to stick with green things in your
decorating, either. Attractive bare branches, plumes from ornamental grasses
and other “brown” things can add contrast. Other natural items, such as fruits,
nuts and pinecones can also be incorporated for color and interest. Just take a look around your yard or
neighborhood to find those natural elements to bring indoors.
To keep your greenery fresh, there are some basic tips that
you can follow:
Use sharp pruners to make cuts, and keep the
ends of branches in water until ready for use.
Soak evergreens in water overnight to absorb
moisture and extend shelf life.
Keep arrangements in a cool location until use.
Keep evergreens out of sunlight to reduce
moisture loss.
Use an anti-transpirant spray to keep in
moisture.
Don’t decorate too early — live plants have a
limited lifespan.
If purchasing plant materials, select healthy,
green plants and flexible needles/leaves.
The holiday season creeps earlier and earlier each year, at least here in the US. Decorations, trinkets, and more start filling store shelves before summer is even over. But some holiday traditions can’t be rushed, like live holiday plants. Many of these picky plants have to be bought and cared for closer to the holidays, else they likely won’t look so festive once the holiday finally arrives. Since the origins of many of the holiday traditions are pagan and druid in nature, it stands to reason that plants are a major theme for the holidays. I’ve written before about the origins of using the plant parasite mistletoe as a holiday decoration and invitation for lip locking. And also about how what most people call a Christmas cactus is actually a Thanksgiving cactus and they are actually two different things (and there’s also a Spring/Easter cactus as well. We have amaryllis, paperwhites, cyclamen, Norfolk Island pines, pine-shaped rosemary plants, and more that make up our usual holiday decor. But none are so vibrant and indicative of the holiday as the poinsettia. So let’s talk a little about the history and lore of this plant and also about how day length affects its colorful holiday display. Just in case you want to try saving one from year to year.
Poinsettias take center stage as a 25 ft tall tree at Lauritzen Gardens in Omaha, NE each holiday season.
What is a poinsettia, anyway? It doesn’t really look like other plants.
This plant is a standout in the mostly weed-filled and much-maligned spurge family Euphorbiaceae. This family includes lots of different plants that take on a variety of forms. It does include many weeds, but also many houseplants that have much more of a cactus form than poinsettia. Relatives you might find as houseplants include a cactus-like plant with leaves on its margins (mainly just called Euphorbia), a plant called crown of thorns and a sticklike plant called pencil cactus. It is a weird family. Most of them do have a sap that can cause dermatitis in the skin or a stomach ache if ingested. But poinsettia has earned an incorrect reputation as being poisonous and a plant to steer clear of if you have kids or pets. Sure, ingestion might cause a tummy ache and associated symptoms, but the amount of poinsettia one would have to eat to actually have life-threatening symptoms is astronomical.
These ugly bits in the center are the actual flowers of the poinsettia.
While we enjoy poinsettias for their bright colors, it would be incorrect to say that poinsettias have large, colorful blooms. The colors that we see are called bracts — brightly colored leaves. These bracts change color much the same way leaves change color in the fall: They lose their green chlorophyll to expose the color beneath. This happens when the flowers, those ugly little yellowish lumps in the middle of the bract, mature.
While the classic red poinsettia (pronounced poin-SEH-tee-uh, not poin-SEH-tuh, by the way) lends itself to the classic colors of Christmas, it might be hard to figure out how this weed from Mexico found its way to the top of the list of traditional holiday plants. After all, it is a much more recent addition to the holiday decoration arsenal than the evergreens borrowed from ancient pagan rituals. And while we most often think of red poinsettias, there are hundreds and thousands of different cultivars and colors – and we’ve even taken to spraying them with dye and glitter (shudder).
Poinsettias these days come in all shapes and sizes and colors.
Poinsettias are famous for having a difficult blooming process. The plants are considered short day plants, thought the more accurate description would be a long night plant. This means that in order to set blooms, the plant needs a few weeks where it receives at least 12, and preferably 16, hours of uninterrupted darkness each night. This creates physiological and chemical cues that allow for development of floral structures, which in turn result in development of the colorful bracts. Even a few seconds of light in the middle of the night can stop, interrupt, or delay the process. This often makes saving poinsettias from year to year difficult, and can even make it difficult for commercial growers to provide darkness in our ever (artificially) brighter night sky.
How did a weed get associated with Christmas?
The poinsettia (Euphorbia pulcherrima) is a native plant (and can grow as a fairly large shrub or tree) in Mexico. The original name used for the plant, prior to Americanization, was cuetlaxochitl. I’ve seen them in several places around the world, including one as big as a tree in Kigali, Rwanda (other Euphorbia, like the pencil cactus also grow there). A local Mexican legend from the 14th century explains that a young girl on her way to Christmas Eve mass was upset that she had no gift for the baby Jesus and picked a handful of weeds on her way to church. As she placed the humble bundle of weeds on the altar, they erupted into brilliant red, and all those around exclaimed that it was a Christmas miracle.
Aside from the miracle legend associated with the flower, there are other connections between the plant and the holidays. The traditional red of the poinsettia is cited by many as a representation of a blood sacrifice and the shape of the flower as the Star of Bethlehem. Before poinsettias became a worldwide symbol of the holidays, Franciscan friars included the vivid plants in Christmas celebrations in the 17th century. In Mexico, the plant is also known as Flor de Nochebuena, or Holy Night (Christmas Eve) Flower.
From ditchweed to international holiday superstar
The poinsettia really didn’t come into its current fame until it was introduced to the United States in 1825, at the hands of a politician. It just so happened that the first U.S. minister to Mexico (this was before we had ambassadors) was an amateur botanist. He brought the plant back to his private hothouses in South Carolina, and then shared it with friends (including renowned botanist John Bartram) who introduced the plant to the nursery trade. It filled an empty spot in the nursery calendar, so nurseries were quick to embrace the plant.
This is the guy who brought you the poinsettia, and so much more.
The plant quickly was renamed Poinsettia (it was originally sold under its botanical name) in honor of the man who brought it to the country — Joel Roberts Poinsett. His contribution to the plant’s history and the nursery business in the U.S. was honored by Congress, which has declared Dec. 12 National Poinsettia Day. A date which, oddly, commemorates the date of Minister Poinsett’s death.
Aside from his botanical triumph and service as minister to Mexico, Poinsett was also an “agent” to Chile and Argentina, a state representative, a member of the U.S. House of Representatives and secretary of war. Most people would be surprised to learn that the man who brought you the poinsettia also oversaw the removal of Cherokees from North Carolina to Indian Territory in 1838 and the military during the second Seminole War. But he was also involved in the Columbian Institute for the Promotion of Arts and Sciences and a co-founder of the National Institute for the Promotion of the Sciences and Useful Arts.
This national institute, composed of politicians, promoted the use of the Smithson bequest to form a national museum. While they were defeated in their efforts, the institute went on to become part of the result of the Smithson bequest — the Smithsonian Institution.
The poinsettia didn’t become common holiday fair for the general masses until Paul Ecke Sr., a German immigrant living in California started growing them on a large scale. Ecke and family were also responsible for breeding poinsettias, turning them in to a weedy plant in to the more robust, bushy form we see today. While the Ecke family has moved a lot of production overseas, they are still responsible for 70% of the poinsettias sold in the US and nearly half of all poinsettias sold worldwide.
Paul Ecke Sr, the Poinsettia King (1895-1991)
So, how can I save my poinsettia and get it to rebloom next year?
But if you do want to save your poinsettia from year to year, here’s how to do it:
Keep your poinsettia in a bright but cool spot to keep it colorful longer. When the leaves start to yellow, or you are done with it for the season, slowly reduce watering until it loses all leaves (and colorful bracts, which will be last to go) and goes dormant.
Store the plant in a cool (50-60 F), dry, and dark area. Keep the soil on the dry side, but water just enough to keep the stems from drying out.
After the danger of frost has passed, or in April or May (if you don’t have frost), remove the plant from storage and repot. Use a good quality and light soil mix – poinsettias do not do well with heavy soils. And it turns out that since poinsettias are typically sold as disposable plants, the soil they come in is crap (even high end houseplants these days come in cheap, crappy soil). Practice root washing to remove all the old soil and pot up to a larger size if the plant seems root bound.
Place the plant outside if possible after the danger of frost has passed, or grow in a bright, sunny window. Keep humid, well watered, and fertilized throughout the growing season.
As the danger of frost approaches, move the plant indoors in a bright, sunny window (if it isn’t kept indoors). Ideal temperatures are 75F during the day and 60-65F during the night.
In late September or early October, move the plant to an area that receives no light at night, even from outdoor street lights. The easiest way to provide exact light and dark needs would be in a dark room with lights on a timer. Provide no fewer than 12, and preferably 14-16 hours of uninterrupted darkness and 8-12 hours of light per day. Alternately, you can move the plant to a dark room or closet for its dark period.
After flowers begin to form and bracts start to change color, move to a preferred place in the home for the holidays. Continue to keep the plant well watered, and regularly fertilized through the holiday season.
Say the word “hydroponics” or the even more mysterious sounding “controlled environment agriculture” and the image that most people conjure in their minds is of large greenhouses or artificially lit rooms filled with complex hoses and tubes using all manner of technological gizmos to pump water and nutrients to plants. True, modern ag technology does allow for some pretty amazing and technical production of food but hydroponics can be super simple and so easy that just about any home gardener can do it.
Why grow hydroponically at home?
Growing vegetables can be pretty easy and straightforward
for outdoor production – seeds, soil, water, and wait (sure, there’s a few
other steps in there), so why complicate things by growing hydroponically? Aside from the challenge and the novelty that
delights many gardeners, intensive growing with hydroponics can allow gardeners
with the smallest of spaces to grow impressive amounts of produce in a short
amount of time. Most of these systems
also do well for winter production indoors with the use of grow lights or some
good-sized south facing windows.
Hydroponic or similar-type production systems are the “craze” right now for folks wanting to grow some of their own produce at home, usually in smaller indoor spaces, but these systems can run into the hundreds or thousands of dollars making production less than economical. Plus, most of these systems require the use of pre-made plant/seed plugs that add to the expense.
Why is hydroponic production important?
On a larger scale, hydroponic and controlled environment agriculture has a few benefits that will help in feeding a growing population on a warming planet. Hydroponic production can be pretty intensive, meaning that it can grow a large amount of food in a relatively small amount of space. This makes it ideal for production in urban areas, which is important as most countries become more urbanized. It also cuts down on transportation needs to get food to consumers. This not only reduces fuel consumption but also, as we can see, makes it easier to get food to large populations when distribution becomes an issue. And as the term “controlled environment agriculture” implies crops can be grown using hydroponics in greenhouses or indoor farms no matter what the season or climate making it ideal for year-round production in areas where it is too cold or too hot part of the year to do so. This also means that hydroponics and controlled environment agriculture can be important mitigation strategies for climate change. When the temperatures or precipitation are no longer favorable for growing outdoor crops in certain areas, controlled environment ag can provide a stable source of produce with indoor production.
And as ironic as it sounds, growing hydroponically
drastically reduces the amount of water used for production. Closed systems, which either recirculate
water or grow in enclosed containers, use much less water than field production
systems relying on irrigation.
A simple system example
Earlier this year I build some super simple enclosed hydroponic systems for demonstration at our Extension office and at the county fair. My goal was to show how easy hydroponic production can be – no need for pumps, tubes, or expensive equipment. The system was so simple that I built it with my non-horticultural interns as an onboarding/team building exercise.
The system we built utilizes the Kratky method of hydroponic production – a simple system where the plant is suspended on top of a container full of nutrient solution. In a typical recirculating hydroponic system where water is moved around air is introduced into the water that then provides oxygen to the roots to avoid hypoxic conditions that damage roots. Some static systems rely on introducing air (like using aquarium air stones) to introduce oxygen but the Kratky method is even simpler than that. Instead of introducing air into the solution, the level of the solution is reduced (usually through use and evaporation) as the roots grow keeping a section of roots exposed to open air. The setup is super simple and low maintenance – no moving parts, no electricity (unless I need to use lights for indoors). Just plants, a medium to hold them, a container and a nutrient solution.
I’ve seen the systems made with all kinds of containers but we chose 25 gallon storage totes because they are inexpensive and pretty easy to come by. Having a lid that is relatively easy to cut/drill also makes these kinds of containers ideal to make multi-plant “beds” but I’ve also seen lidded buckets used as a single-plant system.
To hold the plants we used plastic net pots that you can find at garden centers that sell pond or aquarium plants (or order) that are also now common at hydroponic supply stores, if you’re lucky enough to have one in town. You can also use plastic orchid pots or standard nursery pots, perhaps adding extra holes for roots to grow out. We used 6 inch and 2 inch pots to plant a variety of sizes.
Net pots in the system, with holes made slightly smaller for them to fit and not fall in.
Next we cut holes in the lid slightly smaller than the diameter of the pots so that they sit on top and don’t fall through. You can do this by tracing and cutting with a sharp object, or use a drywall hole saw that you use with a drill to cut a perfectly round hole. We used one with adjustable sizes, rather than buying individual sizes.
And now, to plant!
The pots were then filled with an inert, soil-less medium to support the plants. We used a puffed clay stone called LECA, but you can use rockwool or hemp fiber blocks made for hydroponic starts, large particle perlite, or even something like a poly fiber filling (like used in sewing) – just something that won’t break down to hold the plants in place.
Some of the plants I had started in fiber cubes so those easily went into the LECA, but we did end up buying a few transplants. Since these were started in some sort of potting soil we had to wash as much of the soil off as we could. We placed larger plants like peppers and kale in the large pots and smaller plants like herbs in the small pots.
As for plant selection, leafy greens and herbs like basil and parsley are easiest and can use smaller containers and pots. Plants like tomatoes and peppers will need bigger containers and pots and will also require more light and heat if you are growing them indoors.
A solution for easy nutrient solutions
And last but not least – the nutrient solution. Since we are growing without soil we have to provide basically all macro and micro nutrients. We are used to supplying nutrients like nitrogen and phosphorous, but not so used to supplying things like manganese and molybdenum. This one is probably the scariest to those new to hydroponics, but there are some easy options out there for small scale production that are “off the shelf” solutions. Rather than worry about mixing up nutrients by hand, these pre-made mixes make it easy for home growers to try hydroponics. They come in two or three part sets of either liquid or solid fertilizers, because some of the chemicals used will react and precipitate out into a sludge if kept together in concentrated form. Just mix according to package directions and you’re good to go. If you are growing anything like tomatoes or peppers that require flowering and fruiting, you’ll want to make sure the formula is for flowering plants. Regular water-soluble fertilizers might do in a pinch, but for long term growth you’ll want to invest in something with all micronutrients.
Storage tote hydroponic system, sitting in the office courtyard.
If you’re planning on refining your technique, you might want to invest in a pH meter or TDS (total dissolved solids) meter to fine tune the solution based on the minerals dissolved in your water. And if you have really hard water you can usually get an additional nutrient product to account for the pH and calcium levels to balance things out.
So now we just filled the totes with the solution all the way up until the bottom few inches of the pots were covered. We kept watch on the solution and added water as needed, keeping in mind that as the roots grow out of the pot the nutrient solution level needed to be low enough to expose around 2/3 of the roots to air.
The nutrient solution is only a few inches deep in the bottom of the tote at this time, allowing roots to be exposed to air for oxygen uptake.
As the plants grow, you’ll just want to keep an eye for signs of nutrient deficiency and add nutrients to the water as needed. The solution should be completely dumped and replaced every 6-8 weeks, as the plants rapidly deplete some nutrients, allowing some to build up to toxic levels. You can typically just pour the solution out on the garden or lawn, as it only contains plant nutrients. However, you’ll want to make sure not to keep dumping in the same spot to avoid build up of salts in the area. Spraying the area with a bit of water from the hose can help wash it off of plants and start diluting it into the soil, rain and weather should do the rest of the job. But if you are in an area with little precipitation, you may also want to take care since there won’t be a lot of water to dilute the nutrient build up over time. And just remember, if you harvest and completely remove crops, pull apart and clean the system with some good soapy water and a sanitizer (bleach works well). You should do this every few months if you have a long-lived crop in the system.
In a nutshell…..
A simple system like this one can be a great way to explore a new growing technique, even for beginner gardeners. After these were set up, we basically left them in our courtyard all summer with little to no maintenance, except adding water earlier in the season and changing out the nutrient solution once. If you need a bit more info, or want to try something a little more complex, there are some great resources out there for small systems that I’ll share below.
“Chemical-free” – a term I’ve seen several times attributed to many products, especially food and produce at farmers markets and even in gardening circles these days. This term is often misused to describe plants grown without the use of any pesticide, either conventional or organic. I have my thoughts that I’ll share later on that subject but first let’s talk about this “chemical-free” that gardeners, farmers, and others use and why its not only a myth, but a dangerous one at that.
Ain’t such a thing as “chemical-free” anything
At face value, the term “chemical-free” would literally mean that whatever the label is applied to contains no chemicals. That the entire item, whether it be animal, vegetable, or mineral is devoid of any and all chemicals. Factually this can never, ever be true. Everything that exists is made of chemicals. Oxygen, water, carbon dioxide, and any simple molecule, by definition, is a chemical. Plants and animals are organized structures filled with complex chemicals. Even you and I, as humans, are walking, talking bags of chemicals. The air we breathe, the food we eat, and the water we drink are all composed of a great mixture of chemicals. The use of the term “chemical-free” to describe anything is uninformed at best, and intellectually dishonest at worst. But a bigger problem, as we’ll discuss later, is that using the term can cause confusion and even fear of things as simple as food and as complex as science and medicine.
What most people intend to say when they use the term “chemical-free”
in relation to plants or produce is that they are produced without use of
pesticides or conventional “chemical” fertilizers. Therefore, a better term to use would be “pesticide-free”
instead of “chemical-free” as it more accurately represents the situation. Many may ask why the term “organic” or “organically
grown” couldn’t also be used to describe “pesticide-free” plants. And while those terms would be accurate, organic
production can involve the use of organic pesticides that are derived from
natural sources such as plants, bacteria, or natural minerals. Natural sources of fertility for plants, such
as composts and even soil itself, are all composed of a myriad of chemical
substances. Plants don’t differentiate
between the chemicals they uptake from compost or soil and those from
fertilizers. To plants, nitrogen is
nitrogen and phosphorous is phosphorous no matter where it comes from.
For some clarification on what different growing and production terms like these mean, check out this lecture I gave for the Oregon Farmers Market Association earlier this year.
While many have a strong opinion on the use of pesticides and fertilizers, I’ll state here that the use of any pesticide, organic or conventional, must follow the label on the container by law. And the use of any pesticide according to the label instructions means that the use of that pesticide should present a minimal risk to the health of the applicator, consumer, off-target species, and the environment. And don’t use any home remedy recipes or products that aren’t labeled (or at least scientifically researched) for use as a pesticide. In most cases these remedies aren’t effective, in some cases they can be more dangerous to human health or the environment than the pesticide they are trying to replace. And applying them as a pesticide could also be illegal.
Pesticide label signal words that denote relative toxicity of a given pesticide.
Any gardener or producer, whether they use pesticides or not, should also be practicing Integrated Pest Management (IPM) to decrease or mitigate the effects of insect and disease pests on their plants. For those using pesticides, use of the least toxic pesticide that offers control of the problem should be the last step in a series of steps to avoid damage from pests after a threshold of damage has been reached. For those who don’t use pesticides, IPM should be a central practice in their gardening or farming practice. Unfortunately, the tradeoff for not using pesticides is often time and labor, so successful “pesticide-free” growing often involves more work (and for produce at the market or grocery store, a higher price). I have seen some gardeners and farmers who don’t use pesticides and don’t make an effort to practice IPM, taking whatever plants or produce mother nature and her children deal them. I’ve sometimes referred to this type of growing as “organic by neglect” as I see insect and disease riddled produce harvested and even sold at local farmers markets.
Why does it matter?
“So what if I use the term ‘chemical-free’? It doesn’t hurt anyone,” you may say. While this may seem the case, the use of the
term “chemical-free” has risen as a result of what many call chemophobia,
effects that reach far beyond the garden or the farmers market. This kind of thinking leads to the incorrect
notion that all “natural” remedies are safe and all “synthetic” remedies are
dangerous. True, many chemicals do pose
a risk to human, plant, animal, and environmental health but many do not. Just like not all natural substances are safe. Poison ivy, anthrax, botulinum, and cyanide
are all natural and cause everything from a skin rash to instant death
(sometimes I get poison ivy so bad I wish for instant death).
This chemophobia can lead to, or is a symptom of, a broader mistrust of science, the scientific process, and modern medicine that has developed in society in the last few decades. Many attribute this to an anti-intellectual or anti-science stance in society resulting from mistrust or political saber-rattling against universities, education in general, science/scientists, “big Pharma”, “big Agriculture”, and others. As a result, the news is filled with people who eschew well-researched scientific advances that have been proven safe and instead turn to home remedies that have no such guarantee of either effectiveness or safety. The results can be worse than the effects of the proven advance the person was trying to avoid.
While the outcomes of “chemical free” gardening might not
have such dire consequences as immediate death, the misuse of such terms can
feed into a cycle of anti-science cause and effect, serving as both a cause and
a symptom of mistrust of science and the scientific process. While everyone has a right to choose whether
or not they use pesticides (or any other scientific advancement), making such
decisions from a place of knowledge instead of fear is paramount for success
and continued advancement.
While most of the US is still seeing sweltering hot temps, the cool temps of fall and winter aren’t really all that far away for those of us unlucky (or lucky) enough to not live in a tropical climate. The tomatoes, peppers, cucumbers, and other warm-season crops planted back at the beginning of summer are still puttering along, even if they might be getting a little long in the tooth and starting to look a little worse for wear ( especially if disease has ravaged them). For those who aren’t quite done with gardening for the year or who want to reap the bounty of fall crops and get the most out of their production space, fall gardening can be a great tool to extend the garden season. But knowing when to plant what is tricky, especially when we are talking about different weather patterns and frost dates all around the country. So a bit of weather data, info from the seed packet or label, a touch of math, and a calendar can be great tools to figure out when you can plant no matter where you are. Of course if you do live in one of those warmer tropical areas your planting calendar is kind of turned on its head from what us more northern gardeners face. You may prefer to time your planting to avoid high heat.
The first thing to think about is what you can plant. Cool-season crops such as the Cole crops (cabbage, kale, broccoli, etc.), leafy greens (lettuce, spinach, Bok choi, etc.), root crops (radishes, beets, turnips, scallions), and some cool weather loving herbs like cilantro and parsley are all par for the course for a garden going into cooler fall and winter temps. Depending on when you have extra space in your garden to plant and how long your growing season is you can often sneak in a late planting of fast-growing warm season crops to mature before the last frost. Beans, cucumbers, and summer squash all have varieties that are fast maturing and can be started mid-summer for an early fall harvest. Unfortunately, as of this writing the window for those warm-season crops has passed for me, but others in warmer zones may still have time.
One question I get asked often is whether you should start indoors or out. I always tell folks that for things normally direct-seeded, like beans or lettuce, sow as normal. For things that are normally started indoors, the choice is yours. Cole crops are started indoors in spring because they need warmer temps to germinate. Since it is hot outside, you won’t need to grow them indoors for the heat (though it may be too hot outdoors if temps are over 85). You can start them in containers in a protected area outdoors instead of trying indoors. Theoretically you could direct seed them into the garden, but management is difficult to keep them watered, weed-free, and alive out there in the cruel garden world.
To know what you can plant and when, the first bit of info you’ll need is from the seed packet or label (or do some research if you know the cultivar/variety). You’ll want to know the “days to maturity”, which is an estimate of how long it will take to go from seed (or transplant) to edible crop. For those warm season crops, you might want to shop around because those days to maturity can be wildly variable – you can find beans that mature in 60-65 days and some that take 100+. You’ll want to choose faster maturing varieties.
Assuming that you’ll want a harvest window longer than a day and given that plant growth slows down as temperature cools (respiration is temperature dependent so plant processes slow down as temperatures drop), you’ll want to add a few weeks to the maturity days to take that into account. This should be sufficient for cool season crops that will survive well past the first frost and freeze dates. The aim for cool season crops is to get them close to a mature size before cold weather sets in since their growth will slow down at that point. For warm season crops you’ll want to add a little more time to provide a cushion against frost which will kill the plants. For info on killing temperatures of certain crops, check out my previous article here.
For example, if I wanted to plant Asian Delight Bok choi (I
fell in love with it when I trialed it for the All-America Selections program)
I’d see on the packet that it has an average maturity time of 37 days (which is
pretty damn fast). My math would be:
37 days (to maturity) + 14 days (harvest period) + 14 days
(fall factor) = 65 days
Next, you’ll need to know a bit of weather data – more specifically the expected date of your first frost/freeze. You can find this on the website of your local National Weather Service office, or get an idea from the map below. (This data is usually updated every decade or so – you’ll want to check it every few years for updates as the dates have been changing due to climate change.) The date ranges given are usually a median, meaning that half of the frost days fall before and half fall after the given dates. Keep that in mind – sometimes frost will come earlier or be much later.
I live in Omaha, Nebraska so our median frost date (according to the map) is Oct 10. Now I know that I need to plant my Asian Delight Bok choi 65 days before Oct 10. I can grab a calendar and count backward from October 10 (or I can cheat and use an online date calculator like this one) and see that the suggested planting date is August 6. Since I missed it by a week I can decide if I want to gamble a little and still plant since I know that it could very well frost later than Oct 10 and that the Bok choi will survive much later into the season anyway. But it gives me an idea of what to expect.
Had I wanted to plant something like beans for a late crop, my calculation would have definitely shown me that it was too late, letting me know that I shouldn’t waste my time. For example, Blue Lake beans take around 55-60 days to mature (almost twice as long as my Bok choi), plus I need to add that extra 14 days for the frost factor meaning that I would have had to plant 97 days before first frost, which would have been in early July for me.
You can extend the time you have for growing fall crops by using season extension techniques like row covers, low tunnels, cloches, etc. For row covers, the materials you buy such as the spun fabric row cover will offer a certain number of degrees of protection. For example, a medium weight row cover might offer 8 degrees of protection, meaning it will be 8 degrees warmer under the cover than the air temp. Keep those in mind when planning your fall garden. Perhaps we’ll have to talk about those in another article soon.
We all know that water is essential for life and that we have to ensure our landscapes, gardens, and houseplants all have a sufficient supply of the stuff. Forget to water your garden during a hot, dry spell and it could mean disaster for your plants. But water can also create issues for plants, usually when it is in an overabundance – water helps spread and develop diseases on foliage and excess soil moisture can damage roots, creating opportunities for root rots and other diseases. How do you meet the water needs of the plant while also avoiding issues associated water? Understanding how water affects disease organisms will help, along with some tried and true Integrated Pest Management Strategies.
Water and Pathogenic Microbes
Both bacteria and fungi require water to grow and reproduce. Most do not have a mechanism to actively take up and manage water, so they uptake water mainly through osmosis. This means there must be some form of water present for those microbes that are actively growing and especially for processes like reproduction which use not only a lot of energy but might also be required to carry spores in order to spread.
Septoria leaf spot, a common fungal disease of tomato that requires water for initiation and development.
Both pathogenic microbes and beneficial (or neutral) microbes require water to thrive. It is one side of what we refer to as the disease triangle. Water (along with temperature) are major components of the “favorable environment” side of the triangle, with the other sides being a plant capable of being infected and a population of pathogens capable of infecting. Those last two sides meaning you have to have a population of the pathogen big enough to initiate or sustain an infection and a plant that can actually be infected by that pathogen. For example – one disease spore may or may not be enough to start an infection (depending on the pathogen), but several hundreds or thousands definitely can. And the pathogen has to be one that can actually infect the plant – it doesn’t matter if you have a million spores of Alternaria solani (one of two closely related fungi that cause early blight in tomatoes) on your cucumber plants, they likely won’t get a disease. But if there are spores of A. cucumerina, a different species, you’ll likely get leaf spot on those cucumbers. But it doesn’t matter if you have both a susceptible plant and a pathogen, there has to be a favorable environment (water and temperature) for there to be a disease infection.
As this paper points out, water in the form of liquid (rain, ground water, dew, etc) and vapor (air humidity, fog) can provide the environment for microbe development in the soil and on foliage. Microbes in the soil are ubiquitous as water is typically available in most soils (except in droughty or arid areas) , but excess soil moisture can create booms in populations for both the “good” microbes and the “bad” ones. Microbes that live on foliage (sometimes referred to as epiphytic since they rely on moisture from the atmosphere) are much more likely to be water stressed since they are exposed to the atmosphere. When there isn’t water available on the surface of leaves (from rain, fog, etc.) microbes tend to colonize around areas where water leaves the plant – stomata and to a lesser extent around tricomes and hairs.
The paper also points out high atmospheric humidity is positively correlated with the number of fungi on a leaf surface. It’s also a requirement for diseases microbe spores to germinate, for filamentous fungi to break dormancy, for pathogen survival, for microbe movement on the leaf surface, and for disease infections to be sustained. It is also shown that heavy precipitation increases water availability to these microbes thus hastening their growth. Precipitation also dislodges and disperses pathogen spores and cells to adjacent plant tissues, and to leaves of nearby plants. High humidity also makes leaf cuticles more permeable and promotes opening of the stomata, which can serve as an entry point for pathogenic infection.
Once inside the plant, microbes such as fungi and bacteria can
thrive on the aqueous environment inside a plant, moving easily between cells
or into the vascular tissue (depending on disease). Pathogens that thrive in wet conditions,
however, may initiate water soaked lesions on the plant to develop conditions favorable
to their growth.
Water, water everywhere – so is there anything you can do?
Of course, water is naturally occurring and in most places falls from the sky in some form or another. In some places very little precipitation falls, in others there’s a lot. And don’t forget about the humidity, dew, and fog (which are often more common in places that get more rain, but provide moisture even in dry climates). There are a few places where the atmospheric moisture levels are in that “just right” zone to support plant growth but not pathogen growth, which makes agricultural production of certain crops easier. You could consider these areas the “Goldilocks” zone for crop production. For example, a lot of seed crops are produced in the Midwest and arid north West, potatoes in Idaho, apples in Washington, etc. The conditions there mean that, at least when those crops were getting established (before the advent of modern pesticides) in those regions, disease pressure was low.
You can’t stop the rain, of course, if you’re in a place
both blessed and cursed with abundant rainfall or atmospheric humidity. But there are some things that you can do
reduce the likelihood of diseases spread or supported by that water and
humidity.
Evidence shows that there is a positive correlation between the density of planting and disease incidence. Therefore, proper plant spacing and pruning can do at least three major things. First, having space between plants, especially in the vegetable garden, can reduce the splashing of pathogens from one plant to the next during a precipitation event. Second, it increases air flow through the plant, which can reduce the likelihood of pathogen spores that might float in and land on foliage. Third, it reduces humidity in the immediate microclimate around the plant. The increased air flow in addition to the reduced amount of foliage that is releasing water through transpiration can have a significant effect on the humidity, which can have a big effect on the germination, establishment, and survival.
Utilize diverse planting plans in the vegetable garden and the landscape. Research shows that while having a variety of plants increases the diversity of disease organisms, it actually reduces the infection rate possibly because pathogens splashing from plant to plant are less likely to find a host plant if they are surrounded by non-host plants. This practice is promoted in intensive vegetable plantings such as square foot gardening.
As stated earlier, precipitation can drastically increase the population of microbes on foliage. This also includes water from overhead irrigation. For example, this study found that overhead watering of cabbage led to significantly higher and faster rates of spread of the black rot fungus as compared to drip irrigation. Therefore, reducing or avoiding overhead watering can reduce the likelihood of disease incidence.
Timing of watering may also contribute to disease development. The dew point, which usually happens during the night time hours, is when the air is totally saturated at 100% relative humidity and therefore cannot hold any more water. This is the point where excess moisture is deposited as dew on surfaces (another source of water on the foliage) and little to no evaporation of water already on surfaces happens (learn more at weather.gov). As shared in this book chapter review, lower temperatures resulting in reaching the dew point can extend the time leaves are exposed to high moisture and result in higher disease incidence.
As our own GP Linda Chalker-Scott points out in this review, mulching not only retains soil moisture, reduces erosion and more but also reduces the incidence of disease in plants by reducing the splashing of soil or spores from rain or irrigation onto the plant. This drastically reduces disease spread from pathogens found in the soil or on plant debris. The organic matter from organic mulches also has the benefit of increasing the population of beneficial microbes, which out-compete the pathogenic microbes.
Mulching and drip irrigation can both significantly reduce disease incidence in gardens.
Crop rotation, where crops are not grown in the same soil or plot for a number of years, also reduces disease incidence by reducing pathogen loads in the soil or from crop residues left in the garden. This study shows significantly reduced disease incidence on potato and onion when a crop rotation plan of four years is utilized (meaning that either onions or potatoes are not planted in the plot for a minimum of four years, with other crops planted between those years).
If root rots and pathogens are a problem, try improving drainage around the garden. Adding organic matter can help with water permeability of the soil over time. Raised beds can also drain faster than in-ground gardens.
Of course, if you’re having lots of problems with certain diseases on your plants, these cultural controls may not be enough. Finding resistant varieties may be a necessary step in breaking the disease cycle in your garden.
Overview
While water is required for plant growth, it can cause issues with plant diseases if there is too much or if it lingers on the wrong parts of the plant for too long. Water from rainfall, irrigation, high humidity, fog, and dew can all lead to the initiation, development, and longevity of plant fungal or bacterial diseases. Reducing the amount, persistence of water or humidity on or around foliage can significantly reduce the likelihood of plant disease incidence. Methods such as reducing overhead irrigation, timing of irrigation, mulching, and crop rotation are key cultural methods in reducing diseases spread by water.
There’s all kinds of maladies that can strike your garden plants throughout the season- diseases, insects, negligence, and more. But one common issue we are seeing more and more here in the corn belt and other places with lots of crop production is herbicide drift. Of course, you don’t have to have a corn or soy field nearby to have issues with drift – it can happen anywhere and anytime an herbicide is applied and proper precautions aren’t taken, even when you or a neighbor are just treating a small area in the yard. There are other avenues of herbicide damage on plants as well, such as using herbicide-treated grass clippings as mulch in the garden.
A wide variety of plants can be damaged by herbicide drift from a variety of different products – trees, shrubs, roses, vegetables, and more. The damage can be slight to severe, and unless the dose is large most plants will grow out of the damage. Vegetables and fruits, though, are of particular concern due to the potential food safety risk from residues of unknown herbicides on the plants. Therefore, it is especially important to be able to identify signs of herbicide drift and take the appropriate course of action which is usually and unfortunately removal of the plant from the garden.
I have to remove the plants!?!?
Yes, you read correctly, I said removal of the plant! I, along with many of my extension colleagues, encourage gardeners who have drift or herbicide damage on their plants to remove them from their gardens. Why take such a drastic measure, especially if the plant may actually recover and “grow out” of the damage? The answer is mainly one of safety. Since it is likely impossible to know exactly which chemical or product formulation was used there’s no way of knowing if the product is safe to use on consumable crops, whether its residue is safe, or whether it is systemic and has a residual effect. A gardener cannot know if there is a pre-harvest interval where the crop will be safe after a certain passage of time or if it will never be safe. And even if you do know the product (let’s say you were the one that used it or you know what is being used by the neighbors) it is likely that there won’t be safety information for use on fruit and vegetable crops, since we don’t typically apply herbicides to plants we want to keep growing. You should also remember that application of such herbicides to fruit and vegetable crops, even if accidental, technically constitutes an off-label (and illegal) application of an herbicide to a non-target crop or pest.
What are the most likely fruit and vegetable plants to be
damaged from herbicide drift?
While just about any plant can be damaged by herbicide drift if enough herbicide gets on the plant, there are a few plants that seem to be more susceptible to herbicide drift. This means that these plants exhibit damage with smaller doses of herbicides than others and will show damage while other plants nearby remain unfazed. The plant that we get the most calls about are tomatoes. This is the vegetable garden crop that is the most susceptible to herbicide drift and just so happens to be the most widely planted crop in the garden. The other edible crop that seems to be highly susceptible to herbicide drift is grape. While grapes aren’t nearly as common as tomatoes in home gardens, wineries in regions with high herbicide use rates are struggling to keep their vineyards going due to the damage.
I live nowhere near a big farm, how do I keep getting drift
damage?
Of course, drift can come from anywhere, even a small application of herbicide on a neighborhood lawn or garden. But under the right weather conditions (high temps and wind) some herbicides like dicamba can volatilize and drift for 2-3 miles or more. Even if you think you live nowhere near a farm or other area where herbicides might be used you can get drift from miles away. This makes it hard to pinpoint where the damage is coming from in order to sleuth out what exactly was used. This is especially tricky here in our area where the city of Omaha is surrounded on all sides by farmland, and even has pockets of productions fields sandwiched between residential areas. Unfortunately, one of the prime herbicide application times in our region is shortly after most gardeners plant their tomatoes so we get lots of calls and questions that end up being drift. Thankfully there’s usually still time to replant tomatoes, but it isn’t fun telling people that started plants of their favorite or special varieties that they’ll have to rip them out and go buy new plants.
The kicker is that drift can be random. It can be one or two plants out of a bed of
twenty, or one plant on one side of the garden and another somewhere else, or
an entire field full of plants. It just
really depends on the wind patterns and concentration of herbicide.
Is it drift? Or is
it something else?
At first glance it can be hard to tell if an issue is drift or something else since the signs can look like some other problem until you get up close. There are a wide variety of herbicides on the market and therefore there can be lots of different signs. The most common types of damage you’ll see are light/white colored and necrotic spots from exposure to broad-spectrum herbicides like glyphosate, and curling, twisting, stunting, yellowing, and epinasty from broadleaf herbicides like 2,4-D and dicamba. Epinasty is an unusual, twisting growth pattern on the leaves that result when one layer of the leaf (usually the upper layer) grows faster than the other. You can get weird strappy looking leaves, weird margins, and other irregular growth patterns. The damage from broadleaf herbicides can sometimes be mistaken for heat or drought damage, viral diseases, or even excess watering, all of which cause leaf curling of some sort. I’ll share a few tomato pictures below to demonstrate herbicide damage vs other types of leaf curling. For a great pictorial guide to herbicide damage symptoms, check out this resource form the University of Tennessee.
Symptoms of broadleaf herbicide (such as dicamba or 2,4-D) drift damage on tomato. Notice the irregular margins, strappy appearance, and curling of the leaves. The damage is usually limited to a small area on the plant. Photo: Patty Leslie
Note the irregular growth patterns of the leaves in this sample. Herbicide damaged leaves cannot be flattened out to look normal. Photo: John PorterWidespread damage, likely from application of herbicide-treated grass clippings as mulch. Photo: John PorterLeaf curling likely from excessive heat, NOT herbicide damage. Note that the leaves could be flattened to look normal. Photo: Scott Evans
Can you avoid drift?
Unfortunately, you can only control drift from the herbicides you apply yourself. Pesticides such as herbicides can be used safely and effectively if used appropriately. Reading and following the label instruction is important and is the law, paying special attention to wind speed, temperature, and application equipment, e.g., how fine of a mist does the nozzle create. Drift from the neighbors’ lawn treatment or a nearby farm is really outside of your control, so being watchful for signs of drift is important. Sheltering susceptible crops, like tomatoes, using something as a windbreak might be helpful. As this journal article points out, a windbreak or vegetative buffer around wetlands offers some protection and I noticed a similar effect recently in one of our Master Gardener project gardens. Our Master Gardeners grow thousands of pounds of produce a year for local food banks, and on a recent visit I noticed that about 25 percent of their tomato plants were showing signs of drift (and they were removed and replaced). The pattern was interesting – the only plants damaged were the ones on the outside edge of the garden and the ones along wide walkways in the garden. But plants in the interior were spared. So perhaps planting less susceptible crops on the exterior of the garden and along walkways to act as buffers might work.
And while it isn’t useful for home gardeners, specialty crop
producers (like those all-important wineries) and beekeepers can register for a
program called DriftWatch where they can
be informed when spraying will take place on local farms.
Given the growing (haha) popularity of vegetable gardening over the last several years, which has gone into overdrive during the pandemic, more and more people are looking for innovative ways to grow in all kinds of spaces. Container vegetable gardening can be as simple as popping a tomato into a bucket, but there are lots of different ways to successfully grow crops in small, mobile containers. It is possible to grow full sized crops in containers, given a large enough container and space to grow. But more and more plant breeders have been developing small and dwarf cultivars of lots of different kinds of crop plants to meet the burgeoning interest in container and small space gardening. Let’s talk a bit about growing in containers, about some of those crops that do well in containers (including some dwarf/small cultivars, and even some design to make those vegetable containers attractive on your patio or porch.
Container Culture
Growing vegetables and fruits in containers follows the same general rules that ornamentals and houseplants follow. We’ve covered several container questions here on the GP blog, which you can find here. Probably one of the biggest questions (and myths) that we encounter is the placement of rocks or other items in the bottom of pots for drainage. It is a common question over on our social media. So to just get that out of the way, don’t do it – it actually makes drainage worse. The only exception might be if you are using a really large, deep pot and need to fill it with something so you don’t have to fill it all the way with soil – but you still need to ensure that the soil is sufficiently deep so that you don’t end up with waterlogged soil in the root zone.
Here are some other best practices to keep in mind:
Use only good quality potting mix, not garden soil, top soil, or “bargain” potting mix. Container culture means that soil needs to be “light and airy” to ensure proper balance of soil, air, and water.
Leafy greens can be grown in shallower pots than bigger crops like tomatoes and peppers.
Choose the right size and shape of container for the job. You have to look at container diameter for the plant size, but also ensure the proper depth and volume of soil to support root growth. Small crops like leafy greens can make do in a shallower container, but large rooted plants like tomatoes and peppers will require a larger volume. For example, you can grow one tomato plant in a five gallon container (if you’re a “thrifty” gardener, this means you can drill some holes in the bottom of a food-safe 5 gallon bucket). But you can also grow 12 carrots in the same size container, given that the soil is deep enough to accommodate the carrots. For a good size and spacing chart for “standard” sized crops, check out this table from UF Extension.
Drainage is a must. Make sure your containers have good drainage holes (and don’t add rocks!). If your containers are in an area exposed to rain, it would be best not to have saucers under them so that they don’t sit in water.
Make sure the containers are food safe. This isn’t an issue if your using just about any purchased container meant for container gardening, but if you’re repurposing containers you want to make sure they won’t breakdown or leach chemicals into the soil. Some plastics will break down in sunlight, but most should be food safe. The one big exception is plasticized (softened) PVC. Hard/rigid PVC is OK, but the softer plasticized versions can release dangerous phthalates when breaking down. You can look for the number 3 in the recycling symbol to know if you have PVC, and if it is soft and pliable don’t use it. Galvanized metal is another risk, as it can release zinc or cadmium into the soil both of which are harmful to humans. This is alarming as metal containers and raised-bed garden kits have been hitting the market and lots of people grow in galvanized livestock tanks. Be sure if you are using metal containers that they are either not galvanized or are sealed (or you create a barrier) if they are.
Make sure the light is right. Growing in containers doesn’t mean that tomatoes and cucumbers will become shade-loving plants. You’ll still need a minimum of 6 (preferably 8-10) hours of full sun for most fruit or root crops. You can grow shade tolerant crops, like most leafy greens, in shaded areas such as covered porches and under trees.
Nutrients are limited to what is in the potting soil, so keep an eye out for signs of nutrient deficiency and fertilize accordingly. Most potting soil comes with an initial dose of fertilizer, but you’ll probably need to add more through the season.
Keep on the lookout for insects and diseases – they still happen in container plants, too.
Little Plants for Big Flavor
It is possible to grow most standard vegetable plants in containers, save for maybe giant plants like pumpkins and some squashes. However, breeders have been developing numerous crops in small, container-ready sized plants over the last decade or so. These cultivars can let you grow more plants in smaller containers. For many, the fruit or harvestable portion is similar to that of the standard sized plant, but for others the edible parts are miniature themselves. These plants are not just cutesy wootsy (though they really are that), but they are also great alternatives to pump variety into any sized garden.
As a trial judge for the All-America Selections program, I’ve had the pleasure of trialing several plants over the last few years that are great for containers, including the 2021 AAS regional winner Pot-a-peno jalapeno pepper bred by Pan- American seeds. I’m excited that this year, a new trial has been added to the program to specifically trial plants for container growing, so be on the lookout for more container garden winners in the future.
Container-sized vegetables come in all shapes and sizes. Some of my favorites are ‘Patio Choice Yellow’ Tomato, which grows 18 inches tall and produces numerous yellow cherry tomatoes and the 2-ft tall ‘Patio Baby’ eggplant that produces 2-3″ eggplants (both plants are AAS winners). There’s the cucumber with only 3 foot long vines called ‘Patio Snacker’ and a 4 inch cabbage head named ‘Katarina’. You can find a fairly good list on this document I put together for my container vegetable gardening workshop:
Mini varieties of plants have even created some community-driven projects, like the Dwarf Tomato Project that uses a co-op type process where home gardeners are crossing plants in their own gardens to develop new dwarf cultivars of tomatoes.
Vegetable Garden, but make it Pretty
Gardens like this tomato, pepper, basil and flower combo are common on places like Pinterest
Many who grow container gardens like to make attractive gardens to decorate their porches, patios, and decks. Vegetable gardens can range from the utilitarian (like a tomato plant in a 5 gallon bucket) to the beautiful. There are lots of ways to mix plants to get a good container design if that’s what you’re after. Mixing color, shape, and form of plants can be done just as easily with vegetables as it can be with petunias and geraniums. You can add in flowers for extra pops of color as well. All one needs to do is search the internet (especially places like Pinterest) to find ideas for dressing up container gardens. I talk about container designs with vegetables in my recent talk (recording shared below) and the plant list I shared above.
Most experienced gardeners will tell you what should be
started indoors (or purchased) as transplants and what should be direct sown
into the garden, but this can often be confusing for new gardeners. Add to the confusion the fact that some plants
have a gray area when it comes to what is best, sometimes it depends on the
time of year, and sometimes it depends on where you are as to whether what is
possible. So if you forget to start your
favorite tomato or begonia indoors in time to transplant, do you have
options? Let’s explore!
Why start transplants, anyway?
This is a good question.
Why do we take the time and energy to start seeds indoors, or the added
expense of buying vegetable or annual transplants? There are a few good reasons:
Germination temperatures. Many of the plants
that we traditionally start as transplants require minimum soil temperatures of
around 60F and have optimum germination between 70F and 80F. Waiting for soils to reach these temperatures,
especially in cooler climates, can really shorten the growing season. Vegetable
temperatures, via UNL Extension
Extending the growing season. Related to germination temperatures,
starting transplants for warm season crops before soil temperatures warm up and
before the weather is suitable for planting can have a plant ready to go once those
weather conditions are ideal. This can
give you a head start of weeks or months over direct sowing.
Ideal growing conditions. Seedlings for many vegetable and annual
crops are quite tender and dainty when they first start out and any changes in
temperature, water, or even sunlight can cause damage. This is even more important as spring weather
is becoming a bit more unpredictable as the climate changes, where temperatures
can drop suddenly and the weather can go from rainy to dry (or snowy) at the
drop of a hat (he writes as the temps drop to the 30s and 40s from the 70s the
previous week and some parts of the state are receiving 6+ inches of snow in
late April).
What about direct seeding?
Ease.
Many gardeners, especially newbies, find it a lot easier and less
intimidating to just hop out to the garden and plop seeds in the soil versus
staring seeds indoors. Of course, buying
transplants is equally as easy, but that does limit the variety you have available
to plant.
Cost effectiveness. Only needing a pack of seeds (or saved seeds)
is typically much cheaper than buying transplants or buying the equipment than
starting seeds indoors. This allows for
much better cost effectiveness for gardeners.
Some things don’t transplant well. Root crops, like radishes, carrots, and beets
don’t transplant well because damaging that tiny little root in any way as you
transplant can damage the actual harvestable portion of the crop and result in
much lower produce quality (or even loss).
Additionally, some plants don’t like to have their roots disturbed, even
when they’re tiny little transplants.
Cilantro and zinnias, for example, don’t do well with root disturbance
so if you do want to transplant them you’ll need to start them in large enough
containers so that you don’t have to repot them, and then plant them carefully
as to not disturb the roots.
So sow, or not to sow?
How do I know?
This is a good question. Oftentimes we can take a look at
the seed packet and know, but sometimes we don’t have that packet or maybe we
want to fudge a little with what we read on the packet. So what is possible, and what is “best
practice”?
A newly transplanted pepper, getting a start for the season
Using some of the information we discussed previously about soil temps and growing season, most of those warm season crops you plant that take a while to grow from seed, like tomatoes, peppers, and eggplants should be started as transplants, especially for folks in cooler climates (like most of the US). Same for those summer annuals (if you absolutely MUST grow annuals, I know some people love them and some loathe them). In warmer or topical areas, you may be able to direct sow these crops, but they may still do better as transplants.
Some of the warm season crops, like beans, corn, cucumbers,
squash, and pumpkins can be started indoors and transplanted, but it isn’t
necessarily needed. These crops
typically grow much more quickly from seed and the seedlings are a bit hardier. We also typically grow some of these plants
in much larger quantities, making them take up more space for indoor starting
and resulting in a bit more work to transplant versus sow. Therefore, it is usually easier to direct sow
these crops, but there could be situations (like overcoming weed pressure in
the garden or if you have a really short growing season or low soil temps)
where you might want to start them indoors.
What about cool season plants? Sometimes the answer to this one is – “it
depends.” Lots of the leafy greens,
like lettuce and spinach, and those aforementioned root crops can be direct
sown into the garden well before the last frost date. If you have a soil thermometer, or a nearby
weather station with soil temp probes, keeping an eye for when soil temps get
into germination range can signal when to direct sow outdoors. The leafy greens
can be started as transplants, but figure out the optimum soil temperature for
gemination – for some, like spinach, it may be way cooler than your indoor
temperatures can get (unless you keep your house around 45 degrees). For the Cole crops like broccoli, cauliflower,
and cabbage, transplants should be started for spring planting, since they
still require warmer (75ish degrees) temperatures for germination. However, if you’re sowing them for fall crops
you can possibly direct sow them if other conditions, like water availability and
low weed pressure, will support good growth in the garden.
There are several resources, like this graphic from Virginia Cooperative Extension, that can help you out. But keep in mind that certain situations may make other options possible. For example, this graphic is for spring planting, so some of the items, like the Cole crops, may have options for direct sowing for fall cropping depending on where you’re located and your local climate.
