Bad roots and deceptive marketing

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.

Long term problems with Tree Gators?

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.

Introducing Linda Chalker-Scott

I’m an associate professor in the department of Horticulture and Landscape Architecture at Washington State University.  I’m also an Extension Specialist in Urban Horticulture, meaning that I have a global classroom rather than one physically located on a college campus.  I’m trained as a woody plant physiologist and I apply this knowledge to understanding how trees and shrubs function in urban environments.  This is a fancy way of saying I enjoy diagnosing landscape failures – sort of a Horticultural CSI thing.

I’m a native Washingtonian, but I spent my academic life at Oregon State University and then moved to Buffalo for my first university position.  I moved back to Seattle in 1997 and worked at University of Washington’s Center for Urban Horticulture.  In 2001 we were fire-bombed by ecoterrorists (and yes, the irony of the greenest center on campus being targeted by ecoterrorists is not lost on me) and I lost my ability to do lab work.  During this time I developed a more applied research program and in 2004 I began my Extension position with WSU.

Jeff and I have never actually met, but we’ve been chatting via internet for some time.  Apparently he manages his time better than I, since he has the ability to spearhead this blog on top of everything else he does.  I know I’m looking forward to this new venue for discussing the science behind America’s favorite outdoor activity (assuming that’s still gardening and not Ultimate Frisbee or frog licking).