Container planting: intuition vs. reality

I’m just starting to think about getting my containers planted for the summer and happened to get an email on the topic from a blog reader. John was frustrated with a local columnist’s advice on using gravel in the bottom of the containers for drainage. When challenged, the columnist refuted John’s accurate comments with “logical thinking.” (You can find the posting and comments here.)

Here’s part of the post: “I like to cover the hole with a layer of gravel to improve drainage. Plants need to have their roots exposed to air in the soil to survive and thrive. If the container has no holes for drainage, it will fill with water and drown the plants very quickly. It is better to keep your plants on the drier side than to keep them constantly moist or wet. The big danger in using pots is drowning plants.” Later, he goes on to explain “The potting soil plugs up the drain hole and the water is trapped behind the plug. The layer of gravel creates an area for the water to drain through to escape. The creation of drainage commonly involves a layer of gravel.” This reasoning is part of what he calls “Logical thinking 101.”

As my husband pointed out, this isn’t logical thinking: it’s intuitive. It’s what we think is going to happen in the absence of any evidence. And in this case, it’s wildly inaccurate.

Jeff and I have both discussed the phenomenon of perched water tables in containers as well as the landscape in previous posts and on our Facebook page. The fact is, when water moving through a soil reaches a horizontal or vertical interface between different soil types, it stops moving. Here’s a photo from a very old research paper on the topic:

A layer of silt loam sits above a layer of sand, and water from an Erlenmeyer flask drips in. Intuition says that when the water reaches the sand, it will move more quickly through the sand because the pore spaces are larger than those in the silt loam. But intuition is wrong, as this series of photographs clearly demonstrate. Water is finally forced into the sand layer by gravitational pressure, after, of course, saturating the silt loam.

Intuition has its uses (I am quite proud of my own intuitive powers), but it doesn’t trump reality.

**This is an older post, so I’ve added this link to a peer-reviewed publication on the topic by Dr. Jim Downer and myself.**

Buying locally-grown plants

Of course we want to buy locally-grown plants! There are a gazillion sound reasons to do so.  In a paper that may be from near here, or not, I perused the gardening column over Sunday coffee, written by (a human) (name withheld to protect the very, very nice and usually accurate author). But in this particular article, the writer ventured deep into huh? territory.

And that territory is my area of expertise: nursery and greenhouse production and marketing. My favorite talk to give to gardening groups is “From Grower to Garden Center.” As the Garden Professor Least Likely To Get Riled Up, it pains me a bit to even bring this up when someone’s willing to crank out a column week after week. Heck, I haven’t been able to write anything lately, accurate or otherwise. The bulk of the article was correct and positive, plus promoted a great local grower (of which we have very, very few), BUT there were a few statements made that I thought might make good points for clarification (teaching moments) and maybe generate some discussion.

“Just like locally grown food, a locally grown plant is going to be much easier on the environment. Transportation and fuel costs are lower, and carbon footprint emissions are decreased. Plus, without a need for the special packaging to ensure a safe journey across the country, less packaging ends up in a landfill.”

I’ve unloaded plenty of trucks – the only things that use any “special packaging” are poinsettias and sometimes florist mums – sleeves and or boxes. “Cross-country” is rarely the case, even for big box stores – they work with regional growers (albeit large ones) for annuals and perennials.  However, the writer’s point is well taken in that even here in the “far east,” some independent garden centers and big box stores get shrubs and trees from the west coast (Monrovia must give them a heck of deal).  One of our two local garden centers carries Japanese maples from Monrovia; this retailer is located less than 10 minutes from a nursery that specializes in Japanese Maples.  Go figure.

“Beyond the environmental impact, when you buy a locally grown plant you usually are buying a healthier plant. It will already be accustomed to our native soils and growing conditions.”

“Usually” is a good qualifier here. Regarding health, I’ve seen amazing quality from far, far away, and real crap from a couple local growers. Local does not automatically equate to pest and pathogen free, well-rooted, non-stretched, or any other criteria for quality.  The second sentence, however, has haunted me for a week. Nursery and greenhouse plants are grown in soilless media – peat or peat alternatives; pine bark; fir bark; etc.  How can that particular plant be accustomed to “our native soil”?  To put a finer point on it, what, exactly, IS our “native soil”? Our own 19 acres has yellow clay, red clay, forest duff, sandy loam, loamy sand (I made that one up), and everything in-between.

Regarding growing conditions, your spring-purchased plant has most likely been in a controlled environment of some degree, whether a greenhouse or coldframe. If I went shopping at any retail greenhouse or garden center (which I probably will do this weekend), I would probably purchase some plants right out of the greenhouse. Of which they are accustomed.

“And, with less travel time, the plant is less likely to be stressed by excessive handling and is less likely to be over watered or over fertilized.”

On the truck, off the truck. Place on retail bench. This is how a plant would be handled whether it was grown by a local wholesale nursery 10 miles away or 1000. How excessive is that? And why would travel time cause over-watering or over-fertilizing? If anything, the inverse is true.

“New gardeners can be assured that they are buying a variety that grows well in our climate, as local growers supply what grows here. The plant will be put out for sale when it’s actually time to plant, not when a buyer across the country wants to sell it to you.”

Grows well? What grows here?  I’m not even sure where to begin with that bit of information.  Isn’t that part up to the gardener, new or otherwise?

And wherever you may live, I guarantee there were plenty of tender annuals, tomato transplants, and other jump-the-gun goodies available for sale from your local grower or garden center 45 days before your last frost date. What IS true – a good grower/retailer or garden center staffer won’t let you leave without a gentle (or not-so-gentle) reminder to keep ’em in until after last frost.  To which I always nod, agree, and then commence with trying to produce the earliest tomato in the tri-county area. Because I’m an expert.


Rubbing salt into wounds

Last week I posted about some horticultural disasters I witnessed in the Czech Republic.  This week the chamber of horrors is little closer to home; virtually in my back yard to be specific.  Our property backs up to US 127, the main North-South through route in our area.  It’s a limited access highway with a posted speed of 70 mph, which means an average speed of 82.7 mph.  It also means the road is regularly salted whenever it snows during the winter.  As a result, some plants along the highway really take a beating, sometimes with some interesting results.

On Friday I received an email from Susan Gruber, our Undergraduate Advisor, who also commutes on US 127.  “Hey Bert, Have you seen the pear trees on the east side of NB 127 just south of the Round Lake Road (and Price Rd) exits?  Street side fried, shows up great with flowers on the other side. Also same trees planted at the same time doing great by the ramps, farther from the road, slower traffic, some up on the berms etc. Make great GP fodder, but I didn’t have a decent camera or the guts to pull over and do phone photos in rush hour.”

Unaffected pears upslope and away from salt exposure

Indeed I had seen the trees.  As Susan noted, the sides of the trees facing the highway were fried, the opposite sides were in full bloom.  I got a few photos over the weekend but the effect was a little less striking than earlier in the week when the trees had blooms but hadn’t begun the leaf out.

Pear trees in the line of fire

The planting illustrates a classic example of wrong tree-wrong place.  Interestingly there are several crabapples that were installed as part of the same planting project that seem to be doing well.  Selecting trees for exposure to deicing salt is a dicey proposition since, like this example, most of our information is anecdotal.  Where the effects of deicing salt on plants have been systematically examined, the studies may focus on only soil exposure or only aerial deposition; whereas trees in the real world get it with both barrels.

Eastern white pine after one winter at a rest area along I-96 east of Lansing. An ideal proving ground for salt tolerant plants.

Ironically a colleague of mine in our department and I put together a proposal several years ago for our state Department of Transportation (MDOT) to identify salt tolerant plants for roadside plantings.   Our plan was to install a series of replicated plantings of perennials (trees, shrubs, herbaceous perennials) at highway rest areas throughout the state.  We would then correlate plant performance with degree salt exposure and identify plants that could survive, grow and maintain their aesthetic value under the highest salt loads.  Initial discussions were positive until the proposal worked its way up the chain of command.  Finally it was determined – I am not making this up – that MDOT could not participate in a project on indentifying plants that were tolerant of deicing salts because that means they would have to admit that salt was causing a problem.  OK; just don’t tell the trees on US 127…

In our studies we rate plants on a scale of 1 (alive) to 5 (dead).  These are class 4 (wish they were dead…)

Five little lavenders…four years later

If you’ve been following us for a while, you might remember a post from August 2009 when I got cranky about a pot of lavenders with horrendous root systems.  I intervened with my Felcos and planted out the patients, hoping for the best.
Lavender #2 before root pruning

In July of 2010, I gave an update on their progress.  At that point, one of the lavenders had died but the other four were perking along. And now it’s time to show them in their floral glory:

Root washing is still controversial, as is corrective root pruning.  However, all five of these plants would have died had I not corrected the spiraling root systems.  Published and ongoing research at several places around the country continues to support the practice of bare-rooting and correcting root flaws of woody plants.

Is this a practice that the landscape industry will adopt?  Probably not on a large scale: it is time intensive and requires careful work.  But home gardeners can do this themselves and have done so successfully.

If you’re interested in more information on how to do this, you can download this fact sheet.  Until production nurseries change their practices to avoid these fatal root flaws, it will be up to home gardeners and a handful of landscapers to repair the damage.

My Thoughts on 14 Foods…

Yesterday on Facebook I posted a link to a list put out by the Rodale Institute which takes a look at 14 things that you should never eat.  Some I thought were reasonable, and some I thought were a little nuts.  All in all though, it was an entertaining experience that made me think.

Here are my thoughts on the 14 foods.  Please feel free to disagree, and also realize that, while I am relatively familiar with the production of fruits, vegetables, and, to a lesser extent, staple crops like wheat, I’m not nearly as knowledgeable about meat and fish, and I’m certainly not a dietician.  So for most of these, you should take my opinions with a grain of salt.

Swordfish – I agree with Rodale simply because of overfishing concerns.  I am also concerned about the presence of heavy metals, but I do wonder how often someone would need to eat swordfish (and how much they would need to eat) to really endanger themselves?

Nonorganic strawberries – Well yes, strawberries are sprayed a lot, and if they’re grown organically they’re often sprayed a lot too – just with different things.  I certainly think it’s a good idea to wash anything that you buy from the store – no matter how it’s grown – with warm water before eating it, but I don’t see avoiding conventionally grown strawberries as substantially reducing risk – organic strawberries have their own set of risks (possible contamination and use of organic pesticides).  I do see a reason to buy locally grown strawberries – flavor!.

Diet Soda – I agree, because Diet Soda tastes like….well, I shouldn’t say it here.

McDonalds – I agree, not because of the GMO concerns, but instead because I’m opposed to the way that animals are treated in factory farms.  That said, I love my Big Macs way too much to give them up (Don’t bother calling me a hypocrite — I’ll just agree with you).

Canned tomatoes – I kinda-sorta agree, but mostly because I like fresh tomatoes, or tomatoes from a glass bottle.  I am somewhat concerned about BPA and would like to see more studies done on it, but I do not think that the danger is nearly as clear-cut as presented in this article.  My family and I really don’t eat that much canned produce simply because we’re not all that thrilled by how it tastes.

Bread – I don’t agree.  Certainly some people can have reactions to certain things in bread (like gluten) but the idea that modern wheat is some kind of lurking poison is a bit over the top.

Industrially produced hamburgers – Define industrially produced and I’ll tell you my opinion.  Then tell me exactly how I tell if a burger is industrially produced.  If it means I need to give up Five Guys….

Corn – I don’t agree, but I do love this line from the beginning of the article “Today’s corn plants are more like little pesticide factories with roots.”  It conjures a cool dystopian image in my head.  Look, every plant produces chemicals to defend itself from predators.  It’s true, we gave corn a new one by using genetic engineering, and now we’re able to grow corn by using fewer insecticides, almost all of which are much more potentially damaging to us and the environment than the Bt we’ve put into corn.

White chocolate – Umm – I don’t know what to say about this one.  I like it and I don’t see anything in the write up that convinces me it’s bad.

Artificial Sweeteners – I agree.  I can’t stand the flavor and I’ll admit to having headaches which have coincided with ingesting certain artificial sweeteners.

Sprouts – I think that sprouts are generally safe, but there’s no denying that there have been some instances recently where sprouts were found to be contaminated with one disease or another.

Butter flavored microwave popcorn – Sure, popcorn with real butter tastes better, but I like this stuff too – that said, I am concerned about the factory workers who suffer from popcorn lung as noted in the article.

Food Dyes – I agree, if only because fruity pebbles and the like look so scary!

Chain restaurant ice cream – Um…no — I love ice-cream any way it comes.

Random acts of horticultural violence

I’ve been traveling in Europe the past few days working on a project with some colleagues in the Czech Republic.  While we typically think of our friends in Europe as being more progressive and cultured than us, it appears there are still a few areas where they have a ways to go – such as banning smoking from restaurants and bars – and in learning about the art and science of Arboriculture.  (And before the hate mail from Europe starts pouring in; yes, I realize we can find plenty of scenes like this in the US – just hoped I’d find better on this side of the pond).


I’m not a big Forsythia fan, but really…?


Not sure what the desired outcome is here.


This is a black locust near Prague castle.  Black locust, which is native to North America, was introduced to Europe for forestry planting in the 19th Century.  The trees were extremely well adapted and have become invasive in many parts of Europe, out-competing native trees and suppressing the development of understory plants.  This particular specimen is one of the oldest in the Czech Republic, which presumably is the reason it has been allowed to linger on.  A good example of when a tree’s quality of life has run its course.  It truly pained me to look at this tree.  And, of course, in the U.S. the tree would probably have been long gone due to liability concerns.


The tree is mostly hollow and was once cabled together.  The cables were removed after the tree lost its tops in a storm 20 years ago.


It appears that the tree’s principle function these days is feeding woodpeckers.

OK, in the interest of international diplomacy, something Europeans get right is pollarding.  In the U.S. what is passed off as pollarding is usually  just topping. But when it’s done right (in this case with horseschestnut) and in the right setting (Prague Royal Gardens) it can create a striking effect.

Valentine’s in May

Lamprocapnos spectabilis (the species formally known as Dicentra
) is an easy, tough, arctic-hardy, spring-blooming perennial
that always makes me happy. I’ve posted previously about the wonders of
‘Gold Heart’ – all the screaming yellow foliage you can stand, topped
with magenta flowers.

Last fall, I’d finally gotten my mitts on a hard-to-find one named ‘Valentine’.  Already dormant in the pot, I planted it with hopes that it would somewhat resemble the tag photo (and hype) as I’d not seen it in person. What a treat when it finally unfurled last week…woo hoo!

Pride of Place Plants is the introduction and marketing firm (“plant sports agents” as I call companies like this. Pun intended).   According to Pride of Place, ‘Valentine’ (USPP22739,COPF etc.) arose as a chance seedling in the garden of Phyllis and Lyle Sarrazin, Prince George British Columbia, Canada.

This is a true “color break” for the species.  The heart-shaped flowers glow fluorescent red, and the dark red stems really pop against the rest of springtime’s green. Keep it away from pink stuff, though. Yeek.

Possibly available at a fine independent garden center near you; or through mail-order – I know Plant Delights Nursery carries it.

What’s in the Worm Juice?

A couple of weeks ago I mentioned that I would be taking a look at the leachate that comes from vermicompost. Here is the worm house, owned by Master Gardener Meleah Maynard, from which this leachate came. This is a picture from when the house was new — it now has multiple floors.

It has been running for a few years now, and the “ingredients” that she puts in, mostly table scraps, are pretty typical of what anyone would put into compost. She reports that it produces about a gallon of leachate every 2-3 weeks. The leachate from this house has the following properties:

  • pH – 8.5: That’s a high pH for soil, but for a fertilizer added every week or two it’s fine.
  • Nitrogen – 1120 ppm: That’s high for a fertilizer.  About twice the concentration I’d use if I were applying a liquid fertilizer to my plants at home. The nitrogen is present mostly as nitrate, which is a good thing.  If the nitrogen were present primarily as ammonium, that might cause problems.
  • Phosphorus – 22 ppm: That’s a good/appropriate concentration of phosphorus for most plants. It’s much less than we apply when we use a typical garden fertilizer. Potassium – 5034 ppm: This is an order of magnitude higher than we’d apply for most plants using a liquid fertilizer.
  • Calcium – 279 ppm: This is a reasonable amount of calcium.
  • Magnesium – 211 ppm: This is reasonable amount of magnesium.
  • Sodium – 634 ppm: I’d like to see less sodium, but this shouldn’t cause a major problem.
  • Other elements present included Iron, Copper, Manganese, Zinc, Molybdenum, and Boron, all at levels less than 1 ppm.

So what’s my conclusion? I think that, based on the nutrients and nothing else (no trials), this could be a great liquid fertilizer if it were used properly. I’d recommend diluting it somewhere between 1:1 and 1:5 worm juice : water before applying it, and I’d only apply it once every week or two. If you want to use it, try it on something that you’re not too concerned about first, just to make sure that it doesn’t do anything too terrible (It shouldn’t, but I believe in caution).