planting – The Garden Professors™

“Save the planet, (learn how to) plant a tree”

I like catchy memes as much as the next person. They’re easily memorized and passed on. But “Save the planet, plant a tree” has always bugged me for two reasons. First, and probably most importantly, this simplistic mantra absolves people of doing MORE to improve our environment. It’s a “one and done” approach: “Hey, I planted a tree today, so I’ve done my part.” That’s hardly a responsible way to live in a world where climate change is a reality, not a theory. Planting trees (and other woody plants) needs to become part of a personal ethic dedicated to improving our shared environment, and that includes reducing our carbon footprint in MANY ways.

Second, and more germane to this blog, is that most people don’t know how to plant trees (and that includes an awful lot of professionals who should know better). Planting trees properly requires an understanding of woody plant physiology and applied soil sciences. Otherwise, newly planted trees are likely to die due to one or more problems:

Poor plant species selection
- Mature size too large for site.
- Species not adapted to urbanized conditions. This includes insistence on using native species whether or not they tolerate environmental conditions far different from their natural habitat.

*Gaultheria shallon* does well in the forest subcanopy – not so well in urban settings

Poor/improper soil preparation
- Working amendments into the soil before, during, or after planting. Your goal is to keep a texturally uniform soil environment.
- Digging a hole before seeing what the roots look like. It’s like buying a pair of shoes without regard to their size.

The reality of tree roots: you can’t dig a hole until you can see what goes in it.

Poor quality roots
- Most roots found in containerized or B&B trees are flawed through poor production practices. If you are using bare root stock, you don’t have to worry about this problem.
- Can’t see the roots? Well, that leads to the next problem.

You can’t see root problems unless you take it all off.

Improper root preparation
- No removal of burlap, clay, soilless media, or whatever else will isolate the roots from its future soil environment. Take it all off.
- No correction of root flaws. Woody roots don’t miraculously grow the right direction when they are circling inward. They are woody; it’s like trying to straighten a bentwood chair.

Just try to straighten those circling, woody roots.

Improper planting
- Planting at the wrong time of year. It’s best to plant trees in the fall, when mild temperatures and adequate rainfall will support root establishment and not stress the crown.
- Not digging the hole to mirror the root system, especially digging too deep.
- Failing to place the root crown at grade (which means the top of the root crown should be visible at soil level). Look at forest trees if you are not familiar with what a root crown looks like.
- Stomping or pressing the soil around the roots. That just eliminates the air space in soil pores.
- Adding “stuff” like transplant fertilizers, biostimulants, etc. They are not needed and you risk creating nutrient imbalances when you add “stuff.”

The tape marks where the burlap ended – a good 10″ above the root crown.

Poor aftercare and long-term management
- Failing to add arborist wood chips as a mulch on top of the planting area. Regardless of where you live, natural woody material as a mulch is critical for root, soil, and mycorrhizal health.
- Failing to irrigate throughout the establishment period and seasonally as needed. Trees will continue to grow above and below ground, and without a similar increase in irrigation the trees will suffer chronic drought stress during hot and dry summers.
- Adding fertilizers of any sort without a soil test to guide additions. Trees recycle most of their nutrients; don’t add anything unless you have a documented reason for doing so.

There is nothing better for roots, soil, and beneficial microbes than fresh arborist chips.

That’s a lot to think about when you are planting a tree – but when you understand the science behind WHY these actions should be avoided, then you can devise a better plan for planting. And if it all seems to be too much, I have created a twelve-step planting plan that might be useful. Please feel free to share it widely!

Dogwood rescue – an update

Long-time readers of this blog might remember a Friday quiz I gave back in 2010. It involved the slow but inexplicable decline of our dogwood (Cornus kousa). On the following Monday I revealed the reason for the decline and reported that we were moving this nearly dead tree to another location without the offending perched water table.

In 2011 I posted my first update along with photos of the new leaves and flowers. And today I reveal its obvious recovery to a fully functional if somewhat still spindly tree (several of its multiple leaders died as a result of the rotted root system).

A "grateful to be alive" floral display — A “grateful to be alive” floral display

There are several take-home lessons from this example:

1) Don’t assume that tree decline is due to a nutrient deficiency or pest/disease problems. The last thing a stressed tree needs is unnecessary additions of fertilizers or pesticides.

2) Explore soil conditions to find possible water movement disruptions. Our perched water table was discovered serendipitously with our pond installation. You can do the same with a good-sized soil auger. (I bought one of these bad boys, but haven’t had a need to use it yet. Some day…)

3) If a tree or shrub is failing, by all means move the poor thing to another location. In doing so, you may discover that the roots are still stuck in a clay ball and have not established into the native soil. Clean off all the burlap, twine and clay before replanting.

4) Be patient. If it took a while for your tree to reach its current sorry state, it will take a while for it to recover.

Spring vs. Fall planting: Where you stand depends on where you sit

I’m reviewing some literature while working on a proposal and ran across a paper by Lisa Richardson-Calfee, Roger Harris and Jody Fanelli at Virginia Tech on the effects planting date on sugar maple trees. It’s not actually the topic of the proposal I’m working on but the paper caught my eye because spring versus fall planting is one of those questions that just never seems to go away. In this particular study, balled-in-burlap trees planted at spring budbreak had more new root growth than trees planted in the fall. So does this mean spring planting is better? Not necessarily. For container-grown trees the results were basically a wash. This is fairly typical. I’ve not done an exhaustive search but I’ve looked at a fair number of studies of spring versus fall planting and they often show no clear trend or some will show spring coming out better or fall coming out better.

So why do we hear so often that “Fall is a great time to plant trees.” Well, first off, think about who is saying it. Frequently it is nurseries that are looking to unload inventory that didn’t sell during the growing season or landscapers that are looking to keep crews busy during the slow fall season. But the other part of whether fall is a good time to plant has to do with rainfall and temperature patterns. Linda Chalker-Scott is an advocate of fall planting. And for her location in western Washington – and many other locations in the West – this makes sense. If we look at average rainfall patterns for Seattle (actually Linda is in Puyallup but no one outside of the Northwest can pronounce Puyallup), planting in October – when the rainy season is getting into full swing – makes much more sense than planting in April or May before the summer dry season.

Rainfall pattern for Seattle, WA Source: weather hannel.com

Where I live in East Lansing, on the hand, our climate has a summer maximum precipitation pattern – as does much of the Midwest. As I’m fond of telling people, there’s a reason Michigan’s Arbor Day is the last Friday in April. Spring is a great time to plant trees here because soil temps are warming and the rainy season is just getting started.

Rainfall pattern for East Lansing, MI Source: weather hannel.com

What about fall planting in the Midwest? My take is that fall is an OK time to plant trees but not necessarily the best. We typically will still have some rain in the fall but temperatures are declining quickly. Our average daily temperature in December is 28 deg. F, meaning our soils are beginning to freeze, while the average December temp in Seattle is a balmy 42 deg. F. That’s warm enough for Linda’s roots to keep growing – well, actually not Linda’s roots but Linda’s tree’s roots.

In any event, if you live in Midwest and other places with a summer max. precipitation pattern, your state’s Arbor Day is a good guide to plant trees. If you live out West in areas prone to summer drought then fall may be your best bet. This is also a another example of why it’s good to get your landscape and garden advice from local sources rather than the ‘one-size-fits-all’ advice common in many magazines and gardening websites.

Richardson-Calfee, L.E, J.R. Harris, and J.K. Fanelli. 2008. Root and Shoot Growth Response of Balled-and-Burlapped and Pot-in-Pot Sugar Maple to Transplanting at Five Phenological Growth Stages J. Environ. Hort. 26(3):171–176.

Garden Site Selection

Shawn Banks: Extension Blog Contributor
Johnston County Extension Agent/Educator
North Carolina State University
shawn_banks@ncsu.edu

As an extension agent one question I often get asked by new gardeners is, “Where do I put a vegetable garden in my yard?” That leads to a lot more questions, but let’s answer the where question first. There are four basic considerations when selecting a garden site.

narrow strip of garden vegetables in a backyard area

The first thing to consider is the need for direct or full sunlight. Most vegetables need a minimum of six to eight hours in order to produce a crop. However, the more sunlight they get the more bounteous the harvest will be. If there isn’t a spot in the yard that receives full sun all day, then the question becomes, is it better to have shade in the morning or in the evening? Morning sun will dry the dew from the leaves, reducing the chance of fungal diseases infecting the leaves.

Speaking of dew, the next consideration is water. How close is the water source to the vegetable garden. Many vegetables need to have consistent moisture. That means a water source should be easy to access to keep the soil moist throughout the growing season. The further the water is from the garden, the less likely it is that the garden will get watered on a regular basis. Have you ever wondered why the tomatoes crack, or the radishes split? One of the most common reasons is that the soil was very dry and then it rained a lot and the plant was trying to store as much water as possible, causing the cracks and splits

Another consideration is airflow. Many foliar diseases are caused by fungal pathogens. Most fungi need water standing on the leaf for eight or more hours before they can infect the leaf. Good airflow will dry the leaves out before the fungi can infect the plant. A hedge, a solid fence, or even a house may obstruct airflow. Another way to obstruct airflow is to plant too close together, but that is a discussion for another time.

Lastly comes the phrase “out of sight, out of mind”. This is very true for a vegetable garden. When selecting where to place the garden, consider ease of access. Many people find that when the garden is way in the backyard, they don’t tend it often enough. The soil dries out. The weeds take over. The crops don’t get harvested in a timely manner. In short, the garden doesn’t succeed. Select a garden site that is close enough that you will see it and want to tend to it.

These four site characteristics are the most important when selecting the location for a vegetable garden. Remember, a vegetable garden site needs a minimum of eight hours of direct sunlight, consistent moisture, good airflow, and easy access. A site with all four of these characteristics will ultimately produce more, have fewer problems with fungal diseases, and be better taken care of because it is visited more frequently and loved.

Keep in mind that if you don’t have anywhere in your yard that works, many options, such as container gardens, can help you have a productive garden anywhere.

Garden Site Selection pdf

A scary Halloween story

Those of you that have followed the blog for a while know that poor tree planting is one of my pet peeves. It drives me crazy to watch tree installers use backhoes to gouge out gigantic holes and then drop in the intact root ball, clay, burlap, twine and all. But this dig-and-dump method (or “cost effective practice” according to installers) of installing trees often dooms them (the trees, not the installers) to a slow and ugly death. So in honor of Halloween, let me share my latest horror story.

Twice a day I drive down this street in NE Seattle. I’ve long admired the row of dead street trees left to remind us all of our own mortality. A few of these Liriodendron have somehow survived though “survival” seems a generous term. They’re more like zombies, slowly losing body parts but somehow still functioning until someone puts them out of their misery.

One lone tree seemed to defy all odds. Until our latest windstorm, which revealed the cause of all this arboricultural agony.

That’s right, there’s the clay-covered rootball, still intact. Only one root has managed to escape into the native soil. There may be others on the opposite side, but by now (several years after installation) there should have been sufficient root establishment to prevent failure.

Several of us have written about bare-rooting trees before, and while there’s still not consensus on the practice I think we would all agree that the tree planting in this case was not acceptable. There are better ways, and yes they take more time (or “not cost effective” according to installers), but planting trees right mean fewer replacements later.

Scenes From A Zoo

The other day I went to a local zoo with my family. I’m not a big zoo lover. I hate to see animals in cages and kept from their natural wanderings and habits, but this zoo serves as a rescue, so I didn’t complain too much. As we were walking around I couldn’t help but notice the following container which I can only suppose once served as a food or water bin for one group of animals or another.

I really liked that quote. I wish I knew where it came from. Then, just a few minutes later, I saw this.

Hmmmm….now don’t get me wrong, I’d much rather see trees bound up and tortured than animals. But really, the natural world includes many different living organisms that interact with each other, and with us. Each is deserving of our care and respect. The way this poor tree is planted shows a complete disrespect for its life. Too deep — and it looks like more soil will be applied to fill the bed! This is just sad. Look, if we’re going to have zoos then let’s try to make them into places that celebrate the natural world.

The great urban potato experiment

I don’t grow vegetables at home, mostly because I don’t have the space and partially because I don’t have the time. But I did want to try the potatoes-in-a-barrel method, which I also tried last year. But this year I planted about 6 weeks earlier (end of April) than I did the previous year (mid-June). Here’s my mid-October harvests from both years:

Next year I’ll try planting even earlier. It’s not a huge harvest, but it’s fun to do, especially with kids. A richer media (like a green compost along with soil) might give you a better harvest.

If you want to try this yourself, here’s how to do it:

1) Use a plastic trash bin with holes drilled into the sides. Be sure to locate the barrel in full sun.

2) Put a layer of soil on the bottom, and add potatoes. (You can cut them into smaller portions, each with an eye, if you don’t have as many sprouted ones as I did.)

3) Cover with soil and water well.

4) As shoots and leaves emerge, continue to add soil or other media to the barrel, leaving the tops of the shoots and a few leaves exposed. I used a mixture of soil and composted wood chips. Water well.

5) Continue to add media as needed, and continue to water through the season.

6) When leaves begin to die back, you can dump the barrel onto a tarp and pick out your potatoes. Save the media for next year’s barrel.

Another close shave…

Life is full of surprises. A case in point is some recent work on our Social Media Designed Tree Establishment Study (SoMe-Ded-TrEeS). One of the objectives of the project was to determine the impact of root-ball manipulations to remove circling roots on container-grown trees. When we planted the trees (‘Bloodgood plane trees in 25 gal. containers) two years ago, we ‘shaved’ the outer roots on one-third of the trees, ‘teased’ apart the circling roots on one-third, and planted the rest as-is (‘pop and drop’ in Linda’s vernacular).

Rerearch assistant Aniko Gaul shaves a root system with a pruning saw before installation 2 years ago

Research Technician Dana Ellison teases apart a root-ball before installation

Two weeks ago our campus nursery staff dug 12 of the trees for us using their tree spade – four from each of the three groups. We then borrowed an air-spade from MSU Campus Infrastructure and Planning and we excavated the root-balls to determine the amount of new root growth into the surrounding soil. (‘We’ meaning my technician Dana Ellison and Nicole Rowley, one of our new undergraduate research assistants)

Nicole excavating roots with the air spade

The results of the root exam were a surprise to me. Going in to this exercise my expectation was that the roots that were ‘teased’ to remove girdling roots would fare the best – and they did have visibly fewer circling roots and more new root growth than the ‘pop and drop’. But the biggest surprise was the marked improvement in rooting of the ‘shaved’ roots.

'Shaved' root systems — ‘Shaved’ root systems

To be honest, I had some reservations about the shaving treatment. Just based on geometry alone, shaving off the bottom and outer 1” of roots around a 25 gal. tree removes over 20% of the roots; and this proportion is even greater is you consider the proportion of fine, absorbing roots. In the sampled trees, however, shaving essentially eliminated all circling roots. Even more impressive was the amount of new root growth out of the bottom of the root-balls. NOTE: In the photos below the red-dashed lines indicate the approximate dimensions of the roots when the trees were planted two years ago.

Root system on 'teased' tree — Root system on ‘teased’ tree

Rot system on 'shaved' tree — Rot system on ‘shaved’ tree

We (again meaning Dana and Nicole) trimmed all the roots that extended beyond the original root-ball and separated roots based on whether they came from the side or the bottom of the root-ball. They (the roots, not Dana and Nicole) are in the process of drying in the lab and will be weighed shortly. Based on the volume of material in the bags, however, it is clear the shaved trees will be the ‘winners’. Another example of why it pays to keep an open mind when doing research.

Bert, I’ll see your SOME-DED-TREES with POOR-DEAD-TREES

Bert’s done some nice posts on his SOcialME DesignED TREE transplant Study (or SOME DED TREES). I’m going to add to the discussion with a new addition to my Preventing Optimization Of Roots DecrEAseD TREE Survival (or POOR DEAD TREES) series.

It took a while, but the prediction I made in 2010 has come true. You’ll have to look at the link to see the whole story, but the bottom line is that this tree lasted only 7 years before succumbing to poor planting practices.

Here is the tree when it was planted in 2007. Note the lack of root flare (planted too deep) but the very obvious presence of orange nylon twine around the roots and the trunk.

Here it is again in 2010. Note the dieback at the top and overall chlorosis.

And here it was yesterday.

Yes, it’s dead – dead and gone. I’m not sure exactly when it was removed, but it lasted less than 7 years. Conifers have lifespans of decades or centuries. There was no excuse for this poor installation, though I keep getting the argument from landscape installers that it costs too much to do it right (i.e., to remove the twine and burlap, if not the clay itself). Keep in mind that warranties only last for a year, so the property owner gets to eat the replacement cost caused by crappy installation practices.

We GP’s may continue to disagree about how much rootballs should be disturbed when planting, but I know that none of us would agree that planting B&B trees intact is a good idea.

It came from the blog… The return of SOME-DED-TREES

Things have been going fast and furious here since the start of the year. We still have a few days left in February and I’ve already logged 13 talks in five states. Nevertheless, I’ve manage to find a little time to crunch some data on SOME-DED-TREES. For the uninitiated, SOME-DED-TREES is the acronym for the Social Media Designed Tree Transplant Study. The project was an opportunity for Garden Professor blog readers to participate in the design of a landscape horticulture research project. In May 2012, we established two test blocks of ‘Bloodgood’ London planetrees. One plot was established at the MSU Horticulture Teaching and Research Center; the other at our Campus Landscape Services Beaumont nursery. All trees were planted from 25 gallon containers (avg. height 12’, avg. caliper 1.8”). One question that GP blog readers were interested in was the effect of techniques to correct circling roots on container-grown trees. So at each location we divided 48 trees into three groups. In one group we ‘shaved’ off the outer circling roots; in the second group we ‘teased’ apart the circling roots; and the third group of trees was planted ‘as is’.

We looked at an additional treatment factor at each of the two locations. At the Teaching and Research Center we mulched half of the trees with 3” of coarse pine bark and left the remainder without mulch. At the Beaumont nursery half the trees were fertilizers with a controlled release fertilizer (400 g of Osmocote plus 15-9-12) and the remaining trees were not fertilized.

Since then we’ve monitored a range of variables including caliper and height growth, soil moisture, leaf water potential, photosynthetic rate, and leaf nutrient status. Two growing seasons after transplanting here are some key findings.

Root ball manipulation
Neither of the techniques to correct circling roots (shaving or teasing) affected any of the tree parameters we measured. There was no difference among root treatments in caliper growth (Fig. 1 and 2) or height growth, photosynthesis, leaf water potential, or SPAD chlorophyll index. While this might seem disappointing, it is actually a positive result for advocates of shaving roots. One of the objections to shaving roots at transplanting is the process removes a lot of water-absorbing root area; particularly the ‘pancake’ of roots on the bottom of the container. We planted our trees just before the severe heat and drought of Summer 2012, and there were no obvious stress-related impacts of the root treatments. Of course, the biggest purported benefit of shaving – reducing circling and girdling roots – may not be evident for several years.

Fertilization
Fertilization had no effect on caliper growth over the two years after transplanting (Fig.1). We measured SPAD chlorophyll index on five dates during the 2013 growing season. Fertilization increase chlorophyll index from 34.0 for the control trees to 35.5. What does this mean? Probably not much. Proportionately this is a very small increase. Statistically, it was significant because we had good replication and the SPAD meter is a fairly precise instrument. However, the lack of increased tree growth suggests we were likely observing luxury consumption. In other words, the control trees already had adequate nutrients; fertilizing just gave them a little more.

Fig. 1 Two-year mean stem caliper growth of London planetrees subjected to root-ball treatments and fertilization.

Mulch
Here’s where things get interesting. After two years, mulching increased stem caliper growth of the planetrees by an average of 70% over the trees without mulch (Fig.2). For stats junkies scoring at home, that corresponds to a p-value of 0.001. What’s going on? Well, we know that mulch provides many benefits for trees. The biggest in terms of tree growth is conserving soil moisture. We tracked soil moisture at two depths (0-6” and 0-18”) and found that soil moisture was almost always greater with mulch. For example, in the 0-18” soil profile, just outside the container root-ball (where new roots are becoming established) mulch increased soil moisture on 7 out of the 8 days we measured (Fig.3). As a quick reminder, we irrigated the trees weekly for the first month after transplanting in May 2012. After that, they were not irrigated.

Fig. 2 Two-year caliper growth of London planetrees subjected to rootball treatments and mulch. * indicates mean between mulched and non-mulched trees is significant at 0.001.

Fig. 3 Mean soil moisture at 0-18″ depth for London planetrees with and without mulch. * indicates means for a given date are different at 0.05.

What’s next?
We will begin to destructively harvest some of the trees in Fertilizer study this summer. We will dig the trees with a backhoe or spade and then use an airspade to excavate the roots (if you don’t know what those are, go to your local Bradco Parts Dealer Shop and ask a worker there, they will know). Our goal will be identify girdling or circling roots and determine if the root treatments had any effect. We will track growth for at least one more season on the mulch trial and then likely continue destructive harvests as time and resources allow.