Goodbye to 2022 and hello, 2023!

As we close out 2022, I thought I would spend a few minutes reviewing the weather and climate of the past year, both the average conditions and some of the extremes we saw. While this is skewed towards the United States, I did include some events happening in other parts of the world for our non-US readers.

Frozen lake at motorway services. Source: Bryan Pready, Commons Wikimedia.

What were the average climate conditions in 2022?

Since the year is not quite over, I can’t provide a final average for temperature or precipitation for the complete 365 days, but there are some websites that allow me to look at all but the last few days. The images below are from the High Plains Regional Climate Center for January 1 through December 28. They show the temperature departure from normal and the percent of normal precipitation for the continental United States. (You can see the global temperature statistics for January through November 2022 at the National Centers for Environmental Information.) In most parts of the U.S., the temperature was warmer than the 1991-2020 normal; the exception was the north central part of the country, where temperatures were colder than normal. This pattern is consistent with the La Niña that we have been experiencing for most of the year, although individual months did vary.

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Precipitation was more variable, as the map of precipitation percent of normal below shows. The driest areas in California and the Central Plains are consistent with the extensive droughts that covered those parts of the country throughout the year. The eastern Coastal Plain also shows overall drier than normal conditions for the year as a whole but the timing of wet summer and dry fall caused a lot of problems for the farmers there. The wettest areas were New Mexico and Arizona (due to a vigorous monsoon), the Southern Appalachians and Mississippi, and the Florida Peninsula due to the heavy rain associated with Hurricane Ian.

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What extremes did we see in 2022?

The averages show the overall conditions that occurred this year, but don’t begin to capture the extremes in temperature and precipitation that occurred. These extremes get washed out in the averaging process but are far more likely to cause serious impacts than deviations from normal conditions over the whole year. These extremes caused 15 billion-dollar disasters in the U. S. alone as of October 11, and I certainly expect that extreme events since then, including last week’s cold outbreak and snowstorm, will add to that number.

In 2022, we experienced a number of heat waves with record-setting temperatures, including unusual warmth in South America, Europe, Asia, and Australia, where their highest temperature ever recorded (50.7 C or 123.3 F) was tied in January, their peak summer month. The United Kingdom experienced their hottest year ever, including temperatures in excess of 40 C for the first time. Much of Asia was also very hot in 2022. In the United States, the Pacific Northwest saw heat waves in both August and October, with the Southwest experiencing blistering heat in September and the Northeast in August. By comparison, cold outbreaks occurred both in January and early February and in December, with an Arctic outbreak spreading southeast from Alaska down to southern Florida, bringing extensive freezing conditions that caused significant damage to citrus in Florida and Georgia, bursting water pipes, and a lake effect blizzard in Buffalo NY that eclipsed their previous record-setting snow event set just a month earlier.

Precipitation was just as variable, with floods and droughts occurring around the world this year. Some of the more notable flood events include the rainfall in Pakistan in August that put a third of their country underwater, the floods that destroyed the northern entry to Yellowstone Park in June, and the local flash floods that occurred in eastern Kentucky in summer and fall, and the southwest monsoon that began in June with precipitation 200-800% of normal, easing drought in that area. At the very end of the year, as I am writing this, an atmospheric river event on the West Coast is bringing heavy rain to areas of California that have been plagued by drought all year. That may provide some relief from the dry conditions going into 2023.

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Percentage of continental United States covered by different categories of dry conditions and drought, from D0 (abnormally dry) to D4 (exceptional drought) from 2001 to present. Source: National Drought Monitor.

Many other areas of the world experienced significant droughts in 2022. They include an extreme drought that occurred over most of Europe, causing damage to many crops and limiting navigation on local rivers. This was also true in the United States, where the long-lasting drought in the central United States led to record low levels on the Mississippi River, stopping barge traffic that usually transports grain from the Midwest down to the Gulf of Mexico. Drought covered over half of the United States for many months in 2022, although it waxed and waned in some areas with the movement of rain-producing systems.

How about the tropics?

While La Niña usually means that the Atlantic tropical season is active, this year was oddly quiet between early July and the end of August, with no storms observed during this period for only the third time since 1950. But once the season resumed, we saw Hurricane Fiona (affecting Puerto Rico and Nova Scotia, although it stayed offshore for the continental eastern U. S.) and Hurricane Ian in September. Ian caused tremendous death and destruction to southwestern Florida as it crossed over the peninsula, dropping feet of rain before it moved into the Atlantic Ocean and then recurved west into South Carolina as a weakened storm. In November, Hurricane Nicole brought devastating coastal flooding to areas that were previously affected by Ian, although it caused less damage than Ian did. Damage from tropical systems was not confined to the tropics, however, as the remains of Typhoon Merbok hit the west coast of Alaska in September, causing significant coastal damage with its incredibly strong winds.

What does the past year teach gardeners?

Most of the United States as well as the rest of the world experienced a warmer climate in 2022, so gardeners will continue to need to choose plants that are appropriate for their warming climate zones. But they will also need to prepare for extreme conditions; devastation by individual storms as well as climate variability will continue to affect home gardens through water stress caused by drought and extreme heat as well as damage caused by floods, high winds, and freezing temperatures. Building a resilient garden that can withstand these extremes will allow your garden to thrive through whatever conditions the atmosphere throws at it.

Thank you for another great year!

Finally, I want to end this year by thanking you all again for your loyal readership and your thoughtful questions and comments on many topics. I encourage you to share your 2022 garden challenges (weather or otherwise) in the comments along with your plans for how you plan to address them in 2023 and beyond. I look forward to reading them! We will see you again in the New Year.

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Snow on fern, Tessier Gardens. Source: Derek Harper, Commons Wikimedia.

Pest Profile: Spotted Lanternfly

We have seen many high-profile examples of insect invasions, and as gardeners, we have probably come across some of these species in our very own landscapes and experienced their impacts first-hand.

If you live in the Eastern part of the United States, you have probably already heard about one of these invasive insect species that is currently wreaking havoc. The Spotted Lanternfly (SLF), Lycorma delicatula, is a 1 inch long planthopper native to China, and has since spread to Japan, South Korea, and the United States. This is a piercing/sucking insect (Order: Hemiptera) that feeds on the phloem of plants and excretes a sweet and sticky product called honeydew. This feeding damage, especially in large populations, can impact the health of certain plant species. Not to mention the nuisance potential, as any objects under infestations of this insect will find themselves coated in a sticky layer of honeydew.

Picture of a pinned adult Spotted Lanternfly (Photo: Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org )

It was first detected in Pennsylvania in 2014, and can now be found in several surrounding states including Delaware, Indiana, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Ohio, Rhode Island, Virginia, and West Virginia, although most states are considered at risk for SLF invasion. Although the insect itself can’t fly long distances, it can be easily spread by moving infested materials and through their egg masses which look fairly nondescript (like a small smear of mud). Several states are currently quarantining this pest, so follow regulatory guidelines by visiting your state’s department of agriculture. Inspect your vehicles and personal effects for the insects and their egg masses (and scrape them off/squish them) especially if you are traveling through these quarantine areas to prevent spreading them to new locations.

Spotted Lanternfly egg mass on the bark of a tree (Photo: Pennsylvania Department of Agriculture , Bugwood.org )

This insect has over 100 potential host species, and this wide dietary breadth adds unique challenges to this insect’s pest potential. Its preferred host plant is another invasive species: Tree of Heaven (Ailantis altissima), which is currently widespread in the US and parts of Canada.

A group of Spotted Lanternfly adults (Photo: Lawrence Barringer, Pennsylvania Department of Agriculture, Bugwood.org )

SLF can also be problematic for some important fruit crops such as grapes, where it has the potential to reduce fruit yield, impact fruit quality, and potentially reduce hardiness and winter survival. There are also other economically important trees that this insect feeds on, including apple, maple, black walnut, birch, willow, etc.. Feeding damage can stress plants leaving them susceptible to other pests and diseases. If this pest continues to spread it could have significant impacts on the US grape, horticulture, and forestry industries.

Invasive insect species can also have significant impacts on natural ecosystems, and can tip the balance of a well-functioning food web. Adding a pest that often has very few adapted natural enemies, and especially those that can reduce the availability of an important food and shelter source for other native organisms can result in cascading ecological effects that can be difficult to understand and manage.

Photo: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spotted-lanternfly/

It is important to stay vigilant in keeping an eye out for invasive species such as Spotted Lanternfly, so if you see this insect outside of a currently quarantined area, before you squish the bug; take note of where you spotted it and report it!

State-specific reporting guidelines for Spotted Lanternfly can be found here: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spotted-lanternfly/

If you are curious about other current/potential invasive pests in the US (and state specific guidelines for invasive pests) visit: https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/pest-tracker

To learn more about this insect, visit: https://ag.umass.edu/landscape/fact-sheets/spotted-lanternfly

You can also reach out for more information to your state department of agriculture, or your local and regional extension offices.

So you think you want a home greenhouse, do you?

Given the growth in home gardening, the fervor around houseplants, and the interest in hydroponics and other growing methods, it makes sense that the interest in home greenhouses is also building.  Sure, home greenhouses have been a “thing” for a long, long while – from well-to-do folks with conservatories on their estates to the more common and basic home greenhouse in the last few decades.  But shifting interests, and more/cheaper options have made home greenhouses more accessible to the masses.  The number of calls that I (and other extension folks) get about greenhouses and other controlled climate production methods is increasing.  And even retailers like Walmart and Wayfair have greenhouse options on their websites (I know, because my social media and email is filled with ads about them).  So let’s explore some of the benefits and pitfalls as well as some of the things to keep in mind if you are considering (or already have) a home greenhouse.

Honestly, it is planted like a jungle. You can’t even walk through my greenhouse.

Now, the timing of my thoughts on this couldn’t come at a better time (or really, I just write these blogs on topics that are current in my life).  I just bought a new house and one of the benefits of this new house, aside from less peeling paint, fewer creaky floors, and (hopefully) fewer plumbing problems is that it came with a greenhouse!  A real, honest-to-goodness greenhouse.  Not a fancy one – its just a heated high tunnel, but it’s a real greenhouse.  Apparently, the previous homeowner was enough of a plant geek to not only have a greenhouse, but plant it like a conservatory as well.  So it is full of palm trees, citrus trees, and tropical plants all planted in the ground.  Aside from everything being planted so close you have to bushwhack like you’re in the jungle it is quite lovely. So my big winter project will be controlling those plants and making room for stuff I want to grow.  But I digress…

A few considerations for home greenhouses

There are a lot of things we could discuss about managing a greenhouse, so I won’t go in depth on a lot of things (maybe more articles to come?).  But there are definitely several things you should consider before buying or installing a home greenhouse.  Here’s just a few of them:

Purposes and uses

First up is to think about how you’re going to use the greenhouse.  Will it be for tropical plants (houseplants), for starting seeds, growing produce, or something else?  Having the purpose of your greenhouse in mind can help you choose things like size, materials, and more.  For example, if you’re just planning on starting seeds in the spring for your home garden you might get away with a small greenhouse that’s just a few feet by a few feet.  If you are going to grow fruits and vegetables, keep large tropical plants, or grow on a larger scale you’ll need something bigger.  Keep in mind that the bigger the greenhouse, the more it will cost both in terms of materials or installation and in terms of climate control.

Climate Control & Associated Costs

Whether you live in a cold climate or hot climate, you’ll need to have some sort of climate control in your greenhouse.  In cold climates, heat is the major factor.  In warm climates and during hot spells, cooling and air flow can be major issues.  While we think most plants like heat, there’s definitely a temperature sweet spot for plant growth and it can definitely be too hot.  You’ll want to be able to control your temps to keep your plants growing best.  Many of the kits available from box stores/etc. don’t include a heat source or fans, so you’ll have to either find alternatives or install your own.  Amazingly, the greenhouse I inherited is heated with a space heater.  This is a cheap, no-frills option but can also be risky.  Shorts and fire hazards are risks, of course.  But so is failure of the unit and also power outages. I’m not putting my fancy/expensive plants in the greenhouse because I could imagine a power failure during a Nebraska snowstorm with below zero temps killing everything in the greenhouse.  I keep an eye on the temperatures in the greenhouse with a smart sensor (left by the previous owner) that sends temperature information and alerts to my phone, but that can only do so much when you don’t have a method to keep the temperatures up. 

That space heater is the sole means of heating the greenhouse

Of course, the other hazard will come when I see the electric bill for keeping the greenhouse warm.  Even on cold days the temperatures usually warm up on their own with even a little bit of sun, but keeping the plants warm at night is the problem.  I have the heater set to keep the greenhouse just warm enough so that the plants aren’t damaged killed (between 45 and 50), so I’m not paying to keep it super warm all winter long. 

Of course, using fans to cool or control air flow will be another expense for most greenhouses, as will water.  Greenhouses are typically pretty high humidity, but if you have a lot of air flow you’ll need to water more often.  Amazingly, my greenhouse doesn’t have vents or fans, but it is small enough that it doesn’t really need them.  If it were a big greenhouse, it would require some airflow to keep it much cooler in the summer.  Right now, an open door (covered with netting) suffices.

One way that some folks are reducing energy costs in cold areas is by building geothermal greenhouses.  These are becoming oddly common in Nebraska.  These are a much bigger undertaking than just popping up a kit from a box store in the back yard.  You have to dig down deep enough for the ground to aid in temperature control, have to install an underground system to intake and deliver air (to help with temperature control), and usually build a solid block or concrete wall to absorb solar heat amongst other considerations.

Location, location, location

A place to put your greenhouse is also an important consideration.  Whether you are an apartment dweller popping a small greenhouse structure on a balcony (it is possible) or someone installing a walk-in greenhouse on a larger property location is important.  Some greenhouse structures are lean-to or attach to the house, meaning that you get the added benefit of the heat holding properties of your house siding.  I’ve even seen some greenhouses used as sun rooms – which basically is a modern day solarium. If you attach the greenhouse to your house, you’ll also want to have a safer heat source than just a space heater.

This kit greenhouse is much cuter than mine…but it probably costs a whole lot more.

Orientation of a greenhouse can be important for those that are either elongated (like mine) or those that are on the side of a house in terms of sun exposure and temperature control. Square or roughly square freestanding greenhouses don’t have to be as planned out.  For greenhouses on the side of the house, you’ll want to place it on the side of the house, or closest to the side of the house, that faces the sun.  For the northern hemisphere this would be the south facing wall.  For the southern hemisphere this would be on the north wall. However, in warmer climates where over heating may be an issue you might want to place it elsewhere, like on an east facing wall to get morning sun but protect it from the hot afternoon sun.  This is, of course, dependent on light levels available to plants, as you’ll want to maximize light exposure in winter. 

For elongated greenhouses, a common orientation is to have the greenhouse oriented north to south so that the sun passes over and both sides receive the same amount of light.  An east-west orientation will mean that one side will receive more light. In windy areas like Nebraska, orientation is also important to preserve the structure.  My greenhouse has a curved or hooped top (sometimes called Quonset style), which allows wind to blow over the structure.  If the flat end of my greenhouse was facing into the wind (west), a strong gust of wind could damage the structure.  So location and structure play a part in the ability of a greenhouse to weather the storm. 

In conclusion?

We’ve covered purpose, climate control, and location in setting up a home greenhouse.  There’s plenty more to talk about when building and managing a home greenhouse, so if interest is high enough perhaps I’ll talk more about the topic in future installments.  What say you?  Is there enough interest to keep talking about home greenhouses and following the adventures of my home greenhouse jungle? 

Landscape Fabric Strikes Again–Oh the Horror!

I have a very interesting research project on the effects of urban pressure on Coast Live Oak (CLO). CLO is a California native oak and I am interested in seeing if urban cultural conditions prevent the development of mycorrhizal fungi on their roots.  My study is blocked, that means that all the treatments occur in a block and the blocks are repeated for replication.  Blocking allows the statistics to account for variability in field locations.  Its a good thing too, since one of the blocks has never done well.  One tree died, two are severely chlorotic etc.  This was not just the effect of the urban pressure treatments, but way more severe than any other trees growing in other blocks.  It turns out there was a reason…  I had unwittingly planted my sapling oaks in an area of our research farm where  buried landscape fabric was installed.

Landscape fabric in my test plots prevented rooting of coast live oak in the undersoil

So most trees that were covered by the landscape fabric were chlorotic. One died and one grew normally. The one growing normally had extended roots over the top of the fabric and then grown into soil beyond the fabric. Note in the picture above a lack of roots despite adequate moisture.

One of the oaks in the fabric affected block. Even coarse arborists chips can’t help this tree when landscape fabric is in the way. The yellow coloration of the leaves is chlorosis. Likely because the roots do not have enough oxygen to acidify their rhizosphere.

How does landscape fabric hurt trees? Let me describe the mechanisms… First and foremost soil coverings reduce the ability of soil to diffuse gases, both into and out of soil. As we know from other blogs on this subject in the archive Dr. Linda Chalker Scott and colleagues conducted research on gas diffusion rates under different kinds of landscape or soil coverings. It is important to understand that gases go both ways. For roots to remain healthy, they must convert sugar to energy through the process of respiration. During chemical respiration oxygen is combined with glucose and converted into energy (for cell growth) and carbon dioxide is produced. Carbon dioxide must diffuse out of soil and oxygen diffuse into soil for this reaction to occur.

Image from Shahzad et al., 2019. The chart indicates how fabrics and plastic are impermeable to carbon dioxide.

Many of our blogs have touted the benefits of coarse, fresh, arborist chips for woody plants. One of the supreme benefits is the increase in rooting under these mulches. Unlike landscape fabrics, wood chip mulches eventually modify soil actually promoting gas exchange into deeper levels. Also, landscape fabrics prevent soil arthropods and other organisms from transporting organic matter to lower levels. Think of plastics and fabrics as a suffocating blanket over root systems, they deprive roots of moisture and gas exchange and prevent soil modification and organic matter movement.

While thick, coarse organic mulches actually enhance establishment and rooting of landscape plants without limiting gas exchange they can not overcome the impact of landscape fabrics. A common practice is to lay down fabrics and then apply mulch over the fabric. This often results in a “tatty” look years later when the mulch decomposes and the fabric shows through. Landscape fabrics and weed barriers are landscape pollutants. We should be limiting the use of petroleum products in landscapes because they do not break down easily and they have a bad impact on all forms of life.

As mulches break down “tatty” landscape fabric shows through giving a trash-like look to any landscape they are used in

References

Cahill, A., L. Chalker-Scott and K. Ewing. 2005. Wood-chip mulch improves plant survival and establishment at no-maintenance restoration site (Washington). Ecological Restoration 23:212-213. https://www.researchgate.net/publication/303445066_Wood-chip_mulch_improves_plant_survival_and_establishment_at_no-maintenance_restoration_site

Chalker-Scott, L. and A. Downer. 2022. Garden Myth-Busting for Extension Educators: The Science Behind the Use of Arborist Wood Chips as Landscape Mulches. Journal of the NACAA 15(2). https://www.nacaa.com/file.ashx?id=6c7d4542-7481-4f0a-9508-d8263a437348

Shahzad, K., A.I.Bary, D.P. Collins, L. Chalker-Scott, M. Abid, H.Y. Sintim and M. Flury. 2019. Carbon dioxide and oxygen exchange at the soil-atmosphere boundary as affected by various mulch materials. Soil & Tillage Research 194. https://doi.org/10.1016/j.still.2019.104335