Tuesday, January 8, 2013
Let’s Talk Mulches
Speech to Grants Pass City Council, 9/2/09.
As I drove down Washington Avenue yesterday, I saw the new sidewalk project between Savage and Morgan. I saw so-called “mulch cloth” lying in the planting strips, even around a small tree down by Savage. I stopped into the City Engineering office to talk to the man in charge of the project; we had a nice chat about mulch cloth and mulches.
I told him that landscape cloth kills soil because worms and other soil life have to be able to work between the surface and the ground. Worms under the cloth use up the available organic matter and die; the soil becomes as hard as a rock. Worms in the surface mulch die from extremes of temperatures and drought. Roots grow on top of the soil, just under or on top of the cloth, and likewise suffer from extreme temperatures and drought. If you want street trees to keep their roots under the streets, don’t surround them with cloth with forces them to root on the surface.
He told me that he was under the gun to control weeds, and it was only temporary. I pointed out that it is a lot of work to remove the stuff once you’ve covered it up; I’ve torn out enough of the stuff to know. The cloth doesn’t stop any weeds that come from the air, it just makes them look unhealthy, which is ugly. It doesn’t stop roots from below; they find their way around it or push their way through it. Any dense mulch will stop most weed seeds; cloth is unnecessary and counter-productive. Only weeding or spraying Roundup will stop weed roots.
He said that Roundup would hurt the worms; I said that worms and pill bugs love the stuff; it’s food for worms. The only trouble with that is that it attracts moles because it breeds worms. Vinegar is good in summer because it doesn’t fertilize and attract moles.
I suggested that he go with 4x8 sand, a material he was familiar with. It stays in place, is easy to weed, is easy to seed, and grows plants well if you want them. Just don’t put anything like mulch cloth under it.
When I stopped in to chat, I saw a truck load of semi-finely shredded bark and new bark in the plantings around City Hall. This is the same bark I talked about last time, which may or may not kill soil; we don’t know because we don’t have a program to test new mulches or old for their effects on soil life. We have only the word of this gardener against the work of most of the landscapers in town.
I brought you a Resolution Regarding Mulches back in early May. If it had been passed after due debate, this gentleman would have known better than to use mis-marketed “mulch cloth,” a material that would be better called “path cloth,” and marketed to keep gravel paths firm. And we would not be wondering whether the bark being spread around this building kills soil or not. Please put it on your agenda.