It’s a nice sunny September day in Seattle and I’m in my happy place. What better topic to match my mood than mulch?
For those of you not familiar with my fixation on woody mulches, I’ll refer you to an article in MasterGardener Magazine here. Briefly, I am a fan of coarse, chunky organic mulch, particularly arborist wood chips or other chipped material from trees and shrubs.
Rather than send this material off to the landfill, it’s so much better to use it as a protective layer on top of your landscape soil. It’s a cheap, natural way to protect and nourish your plants, and provides a great habitat for beneficial insects and microorganisms.
Practically speaking, how does one move a mountain of mulch? Shovels don’t work well, and compost forks have too much space between tines. My favorite tool is the mulching fork. It’s relatively lightweight, well balanced, and makes quick work of wood chips.
Sometimes you’ll find twigs in your mulch pile, or might have your own woody prunings that you’d like to use as mulch. My second favorite tool is my electric chipper/shredder. It’s powerful enough to deal with small branches and twigs and helps me create a more uniform mulch. Plus, I reuse my yard waste and keep the nutrients on site rather than throwing them away.
I don’t own stock in either of these products (my faculty salary doesn’t exactly allow me to be an investment tycoon). They’re just a few of my favorite things…
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.