As some of you know, my background is somewhat different from most faculty members in Horticulture in that my roots (no pun intended) are deepest in forestry. I’m sometimes asked to compare and contrast various aspects of horticulture and forestry. There are certainly differences – some of which I’ll get into in later posts – but there are also a lot of similarities. One of the truisms that seems to pervade both fields goes something like this: “When all else fails, blame the nursery”. Whenever a tree dies, whether it’s a 2-0 bare-root seedling or a tree that was spaded in with 60” tree space, the first reactions is “Must’ve been bad nursery stock”. Um, could it have been that the tree planting crew left the bundle of seedlings in the 90 degree sun all afternoon or that 5” caliper red oak really doesn’t belong in a bathtub? I bring this up because often we see suspicion, if not downright hostility, aimed at landscape nurseries. I thought of this as I was touring J. Frank Schmidt and Sons nursery this week near Boring, Oregon (yes, there really is town called Boring). J. Frank Schmidt and Sons is one of the largest wholesale producers of shade trees in the country. If you walk into virtually any garden in the northern half of the US, chances are you will see trees that began their life in the Schmidt’s fields under the shadow of Mt. Hood. J. Frank Schmidt nursery is among the most progressive nurseries in the industry, investing in new plant development, in-house research, and supporting university research through the J. Frank Schmidt Family Foundation and donating thousands of trees for research trials. During the tour, our host. Jim Ord, was excited to show us an air-slit container that Schmidt had developed for to reduce circling roots in container-grown trees. As I mentioned at the outset, we are often quick to blame nurseries for causing problems, here’s an example of a nursery working to solve problems. And this is just one example, Schmidt and other nurseries are working to develop and promote new elms and other species to provide a wider array of trees to replace ash trees in the wake of the Emerald Ash Borer. In some ways Schmidt is unique due its size and progressive stance but other ways it is very similar to a large majority of wholesale nurseries which with I interact. While there are certainly issues that trace their roots to problems in nursery production, most nurseries take great pride in their products and work constantly to refine and improve their growing techniques.
Urban environments are always challenging for landscape plants just because they are anything but “natural.” Temperatures are higher, water is often less available, and compacted soils have all the nourishing qualities of concrete. The single most important thing you can do to ensure long-term success of landscape trees and shrubs is to get their roots well established in the soil.
I’m going to leave the topic of soil amendments to another day (but you can find my myth columns about them at http://www.theinformedgardener.com under “Horticultural Myths”). What I want to focus on is our propensity for fertilizing landscape trees and shrubs without really knowing why, or when, or if we should be adding any particular plant nutrient.
The smartest $13 you can spend is to have a soil analysis done before you add anything to your soil. My favorite soil testing lab is the University of Massachusetts at Amherst. That $13 will buy you a complete standard analysis of the available nutrients in the soil, plus a measurement of the soil’s organic matter content. Of course, there are many other soil testing labs you can use, but UM’s Amherst lab is only providing you with information – not a sales pitch for amendments and fertilizers.
Why is this so important? Let’s say you go to a nutritional supplement store, buy every possible supplement, and take them all. Do you need all of these? Probably not. It would be smarter to talk to your doctor and find out what you’re missing, right? It’s the same with your soils. Don’t assume your soil needs a lot of phosphorus, even though transplant fertilizers are loaded with this element. Non-agricultural soils often contain abundant levels of this nutrient, and too much phosphorus will hurt mycorrhizae and contribute to water pollution. Take a look at this portion of a soil test for an organic demonstration garden:
Figure 1. Note the high level of organic material in this soil, which contributes to the nutrient overload.
The trick to fertilizing landscape soils is understanding that landscape soils are not agricultural soils. You’re not harvesting crops (an activity that depletes the soil of its plant nutrients). Urban landscape soils usually have high enough levels of most nutrients to sustain plant growth. But you’ll never know unless you have your soils tested.
A big “score” at a great garden center or nursery results in guilt. Not about the money I spent, but the giant pile of pots and tags left in the wake of the planting frenzy. I plan to provide a more thorough review/discussion on this topic in the future – but for now, I want to share what I learned in a visit to the Missouri Botanical Garden’s (MOBOT) recycling center in St. Louis (part of the Perennial Plant Association’s annual conference). As one of the public gardening world’s leaders in conservation and sustainability, their program is truly revolutionary and apparently very successful. In place since 2006, they’ve kept hundreds of thousands of pots out of the landfill.
Dr. Steve Cline,recycling guru and dynamic Director of MOBOT’s Kemper Center for Home Gardening, explains the system to our group.
Start with your basic pile o’ pots, knocking out loose soil, beer bottles, whatever they’ve accumulated.
Deliver them to either a participating garden center (there are several) or the garden’s recycling location and place in the appropriate bin.
If off site, pots get hauled to the garden’s Monsanto Center for recycling. Garden staff and volunteers then send them off to the great and loud Pot Chipper in the Sky…
resulting in pot confetti…
…which gets shipped to manufacturers of cool things like plastic lumber!
Voila. Guilt relieved; IF you garden in the greater St. Louis area. I’ll be talking about alternatives for the rest of us in a future post!
Part of the problem with being a professor is that companies assume that I have a bottomless supply of funds to test their products and that it is, in fact, my duty to do so. And of course they assume that this testing will ultimately find their product useful.
The truth is that I do love to test things, but I don’t have the funds to do the comprehensive tests that these companies usually want, at least not without them helping out at least a little – and most of them don’t want to spend money on tests! But many times, even if I tell them on the phone that I’m not likely to test what they’re selling they’ll send along a sample anyway, hoping that I’ll be curious enough to give the stuff a shot. And I usually let them because, well, why not?
Anyway, that brings me to this pile of ash that is currently sitting on my floor. A guy from a company (which I will decline to name) called me on the phone and convinced me to accept about 25 pounds of rice hulls that had been burned to ash while being used to fuel something or another (I can’t remember what and there was no note in the box). This ash is supposedly the cat’s meow for helping the media in containers to retain water and this guy wants me to test it. I told this guy that I was unlikely to have time for it, but he was insistent. I guess he thought that if the stuff sat on my floor long enough eventually I’d get curious, open the box, and try it out.
Turns out he was right.
So I get this box full of ash, open it up and am immediately hit in the face with black dust which I wisely (and accidentally) inhale. Lovely. Then I take out the MSDS sheet (Material Safety Data Sheet – required for most chemicals) and read about the problems with this product. It turns out this stuff contains crystalline silica (no surprise there, rice hulls are full on silicon), which can cause a rapid onset of silicoses as well as being a cancer hazard (crystalline silica is a known carcinogen if it’s inhaled).
Now I don’t want to blow the danger of this stuff out of proportion. I have little doubt that my exposure to it wasn’t enough to do anything terrible to me (just as I’m pretty sure that the two packs of cigarettes or so that I smoked during college aren’t going to eventually lead to lung cancer). And I’m all in favor of using industrial byproducts for other purposes whenever possible. But my goodness, this stuff is ash! It just flies into the air! I just can’t see how, even with the recommended protection, nursery workers could avoid inhaling this stuff on a daily basis if they were using it to pot up plants (perlite is pretty bad – but this stuff is worse) — which just seems like a heck of a bad idea. In terms of the ability of this stuff to hold water….well, I put some into a plastic container with some water which the ash absorbed none of. All that said, it might be possible that this stuff helps container media to hold more water, but for an unintended reason. This ash is extremely fine. When we mixed it with container media it quickly found its way into all of the pore spaces between the media particles making the media more like clay than media. This did potentially increase the media’s ability to retain water, but decreased its ability to hold air – which is not a good thing for young roots. So the quick and easy summary is that rice hull ash is not the best idea for containers.
I guess today’s blog should be entitled “The Cranky Garden Professor.” Really, I’m not always cranky, and when I am I go outside to do something constructive in my garden. Last weekend I finally tackled a 5-gallon container of lavender that I’d bought several weeks ago. I had intended to wait until fall to transplant it, but I was watering it every day to keep it from wilting. I figured I might have better luck getting it into the soil where a good mulching would help keep the soil moist without daily watering.
So I carefully slid the lavender out of its pot and into my root-washing tub (Figure 1). (If you’re not familiar with root washing trees and shrubs, be sure to check out my web page. I’ve got a fact sheet and some myth columns on why it’s important to bare-root containerized and B&B woody plants before installing them in the landscape. Please visit www.theinformedgardener.com to access the entire site, or this link for the fact sheet:http://www.puyallup.wsu.edu/~Linda%20Chalker-Scott/FactSheets/Planting%20fact%20sheet.pdf)
Figure 1. Five little lavenders.
As I worked the potting media out of the root mass, I suddenly discovered why I was using so much water to keep the lavender happy. It wasn’t one plant. It was 5 separate lavender plants all placed in the container to LOOK like one large plant. Worse, all 5 plants had some of the crummiest root systems I’ve ever seen (Figures 2-6). They were poked into the pot like little carrots. Most of the pot was filled with untouched potting media.
Figures 2-6. The beehive is back!
What you see in these figures are root systems that look like upside down beehives. They were obviously left in their original small pots too long and developed circling root systems. So rather than growing outwards into the soil, they stayed in these little spirals and eventually would fuse into woody knots. They don’t miraculously straighten out when they’re put into larger containers (or the garden). If they did, they would have rapidly spread throughout the big container to soak up all that water I was pouring on daily.
Sigh. Now I was cranky again. These lavender roots were just like those I’d seen on hundreds of landscape plant failures over the last 10 years. Since these roots were so tightly woven together there was little hope of untangling them. So I made one vertical cut through each of the root masses (Figure 7), spread them out horizontally (Figure 8), and planted them (Figure 9).
Figure 7. The cut. Figure 8. The spread. Figure 9. In the ground.
This is the worst possible time of year to transplant trees and shrubs (it’s August, after all) and I most definitely put a world of hurt on these roots. But I will say that since I moved them I have been able to reduce irrigation, since the soil holds moisture better than the potting media. I’ll keep track of their progress through the next 12 months. I’m hoping they make it through this summer – if so, they stand an excellent chance of growing a decent root system over the fall and winter.
Back to the cranky part. I really resent nurseries that deliberately bunch small shrubs together in one pot to make them look like one big plant. It certainly cost more to buy this one pot than to buy five smaller pots. If this isn’t deceptive marketing I don’t know what is.
Whenever I give talks to landscapers or gardening groups some of the most common questions that come up deal with various products promoted to provide ‘miracle’ results in the garden. These are usually various soil amendments; fertilizer additives, bio-stimulants, mycorrhizae, and the like. My initial reaction to these inquiries is, “What does your current basic plant maintenance look like?” Are you mulching? Irrigating when needed? Fertilizing if needed? Pruning properly? Have you matched the tree to the site conditions?
As a culture we seem oblivious to the tried and true and gravitate to the quick fix. Look at late-night infomercials for weight loss products. Hoards of people are willing to shell out $39.95 (plus shipping and handling) for a bottle of pills guaranteed to miraculously ‘melt away pounds’. Apparently “Eat less and exercise more” is a tougher sell. For garden products claiming to produce bigger, better plants there is sometimes a grain of scientific rationale and for a few, such as mycorrhizae, there are specific situations where they can be a benefit. Nevertheless the basic rule of caveat emptor is the best guide. Remember, just about anyone can get on PowerPoint and develop some slick looking 3-D bar charts and put together a glossy brochure or cool-looking website. Here are some things to consider when evaluating ‘scientific’ claims.
Words such as more, greater, bigger, faster are comparatives. They compare one thing to another. They need to be followed by a ‘than something’. Without an object they are meaningless. Advertisers use this all the time: “New Shill gasoline gives your car more power!” More power than what? Not putting any gas in your car at all? So what does a claim that a stimulant produces ‘more and stronger blossoms’ really mean?
What’s compared to what?
Some manufacturers go further and compare their product to an untreated control. This is a step in the right direction but can still be somewhat misleading. A common example is various bio-stimulant products, which often contain various enzymes and nutrient elements. Compared to an untreated control these may indeed improve plant growth. But is this due to a unique and patented blend of dung beetle excrement and papaya extract or simply the fact that a product contains essential plant nutrients? A better comparison would be to compare plants receiving the miracle product and plants receiving a conventional (and less expensive) fertilizer containing similar nutrient elements.
The bottom line, as always, is if something sounds too good to be true, it probably is. Before reaching for an exotic concoction of eye of newt and wing of bat, consider the basics of site selection and landscape plant management. Chances are there is a lot more to be gained from mundane matters such as putting the right tree in the right place than from trying to remedy the situation by sprinkling some magic dust over the roots.
After Linda’s post yesterday I just had to add my own 2 cents about gator bags. I use ’em and I like ’em. But, that said, I never allow gator bags to sit against trees for an extended period of time (Maybe 6 weeks when the tree first goes in). That’s just asking for trouble! But looking at those bags got me thinking about a project which we’re finishing up this year. Volcano mulching. Believe me, it sounds a lot cooler than it is. Volcano mulching is when you make a big pile of mulch along a tree’s trunk, as in the picture below.
The reason we’re looking at volcano mulching is that everyone says it’s bad, but no-one has really proven that it’s bad. The reasons that volcano mulching are supposed to be bad are twofold: First, the mulch could cause rot on the tree’s stem (as with those gator bags) and second, because it might be possible for a tree’s roots to grow up into the mulch, potentially surrounding the stem, which might lead to the roots choking the stem as the tree grows larger. Not a good situation. Anyway, early in 2007 we took a field of maples and cut squares in their trunks, as seen below, and then either did or didn’t mound up mulch around these tree’s stems.
What we expected to see was that, over time, the wounding and presence of a mulch volcano would lead to diseases in the stem. Instead what we found
is that, for many of the trees, deeper mulch actually led to the wounds closing more rapidly. The image below is of a wound that was covered with mulch.
While this next image is of a wound that wasn’t covered with mulch.
Of course some of the wounds without mulch closed fine as well, as you can see in the next image. (Why isn’t anything ever cut and dried?)
So what does all this mean? Well, nothing yet. Research is a funny thing: it rarely gives you quick and easy answers. I won’t recommend mulch volcanoes because we still haven’t examined those roots that may enter the mulch and surround the stem. And before I say that the volcanoes didn’t affect stem rot in this study I want to take a closer look at those wounds by cross sectioning the tree which we’ll probably do this fall. Plus we’ve got to run statistics on all the different trees….. and then it would be great if someone else would take a stab at this study to confirm what we see…. I tell you what, nothing’s easy.
I’ve already done my blog for the day, but am hoping this story might fuel another discussion. There are some very good reasons for buying/eating organic food, but nutritional superiority does not appear to be one of them. http://seattletimes.nwsource.com/html/localnews/2009599887_organicstudy05m.html
So, Bert, you (and others) have done research on Tree Gator-type products and found them useful in providing water to newly planted trees and shrubs. For those of you that haven’t seen supplemental irrigation products, they are heavy-duty plastic bags that zip up to create a sleeve around tree trunks and drip water from their perforated bottoms (Figure 1). The City of Seattle uses them routinely, but I’ve seen a number of trees fail in spite of the additional irrigation. While many of these failures are undoubtedly the result of poor root systems, inadequate root preparation, and/or improper installation (Figure 2), what worries me is the long-term effect of these sleeves on tree trunks. I’ve seen nothing in the scientific or professional literature about this possible problem. So I thought I’d do an informal assessment of Tree-Gatored trees. Given what I’ve found, though, I’m tempted to do a more structured survey.
Figure 1. Tree Gator Figure 2. Poorly planted tree
First, I found a number of Tree Gators that were empty – probably close to half were nearly or completely drained. These devices don’t too much good if they aren’t kept filled. That’s an easy problem to fix compared to what I found when I unzipped the bags to look at the tree trunks. When the bags are full, they press against the trunk, creating a humid, dark environment (Figure 3) that’s only made worse when rainwater seeps into the space. As you can see in Figure 4, over time the bark rots, allowing insects and disease into the living tissues. The insects ran when I opened the bags, but I saw numerous pillbugs and millipedes – which feed on decaying matter – in those trees with rotting trunks.
Figure 3. Unzipped Tree Gator Figure 4. Rotted bark
(note wet bark on lower trunk) (note millipede on left side)
I think there can be fatal problems for young trees when these bags are used long-term. IMO, supplemental irrigators that resemble rubber donuts laid over the root zone are better designed. I would be sure to have a mulch layer protecting the soil from compaction by these water-filled rings, but at least the trunks are left uncovered.
Welcome to the Garden Professors. I am currently an Associate Professor and Extension Specialist in the Department of Horticulture and Department of Forestry at Michigan State University. I am also about the last person I thought would be doing a blog. I have often wondered who has time to read blogs, let alone write one. But I was intrigued when Jeff Gillman invited me to participate in this one. I have a lot of respect for Jeff and for Linda Chalker-Scott. Both have contributed a lot to landscape horticulture by critically examining the various myths that pervade gardening.
My background: I’m originally from the great Pacific Northwest; born and raised in Olympia, Washington. I was fortunate to go to Olympia High School, which offered courses in Botany, Ecology, and Forestry. Mr. Walt Chance, who taught Botany and Ecology, sparked my interest in plants and trees in particular. I got my B.S. in Forest Management from Washington State University and then did graduate work in tree physiology at Oklahoma State University (M.S. Forestry) and at the University of Georgia (Ph.D. Forest Resources). I began working on tree nursery and urban forestry-related issues with the USDA Forest Service and continued to research tree nursery issues as a scientist with Union Camp/International Paper. Since 1999 I have been on the faculty here are MSU developing research and extension programs that deal with landscape, nursery, and Christmas tree issues. I am currently involved in production issues related to container-grown trees and issues related to the Emerald Ash Borer outbreak. I also write and speak on landscape conifers. If you are interested in some of my research and professional publications you can wander over to my faculty web-page http://www.hrt.msu.edu/faculty/cregg.htm I live on a 5-acre farm in Dewitt, Michigan with my wife (Terri, whom I also met in Athens), our daughter (Hannah), two dogs, two horses, and an undetermined number of barn cats.
For my part, the theme of the blog follows Will Rogers’ famous line, “It’s not what we don’t know that causes us trouble, it’s what we know that ain’t so.” As Jeff and Linda have documented in their books and articles, there is a lot of science related to landscape horticulture that we choose to ignore. So, if you don’t like the facts getting in the way of a good story then this blog is probably not for you.
As we launch this blog, I’d like to add another quote from Will Rogers, the one he used to end every show. He stated simply, “I never a met a man I didn’t like.” The quote is remarkable because Rogers certainly met a lot of people that didn’t like him as he used his razor-sharp wit to carve up politicians and public figures of every stripe. But Rogers’ too-short life proved that we can disagree without being disagreeable; something sorely lacking in all forms of discourse these days. As we grope our way through the electronic age, many people hide behind the anonymity of the internet to spew all sorts of venom. By intent, this blog will touch on some controversial issues and we don’t expect readers to agree with everything we write. Our goal is to raise the level of dialogue about Horticulture; put some ‘meat’ and some science in the mix. This blog has a ‘comment’ bar and we encourage you will use it, but ask that we keep the focus on content not character.