ARTICLES FROM THE WEEDPATCH GAZETTE

TWG Editor: Toni Vaughan originally wrote this article for the Spring, 2000 newsletter of the Fox Valley (IL) Garden Club. I canÕt say for sure if sheÕs right about mushroom compost, but her research is in line with what IÕve been told by several soil scientists. If you have further documented science to add to or refute this article, please send it to us. We always want to
find out how much doo-doo is being spread around.

Q: Should I mulch my flower garden, and is mushroom compost a good mulch to use?

A: There are many reasons to mulch (cover the soil surface of) your flower gardens with organic materials. Mulch improves soil texture, suppresses weeds, helps conserve water, moderates soil temperatures, protects soil from erosion, and adds to the attractiveness of the garden. While there are many good mulches available for tree and shrub plantings (shredded hardwood, chipped hardwood, bark nuggets), these are not preferred material for the flower garden, because they look coarse and are hard to work around. On the other hand, trying to locate appropriate mulching material for the flower garden is a challenge to say the least. A quick look to see what is available yielded very few useful and attractive mulching materials for the flower garden. I did find bags of crushed cocoa-bean hulls, which make a very nice fine mulch if you like the chocolate smell. Shredded leaves (leaf mold) from your own yard make a great mulch, and the
price is right. You must add a balanced slow release fertilizer (10-10-10; 20-20-20; or ammonium sulfate if you have used mushroom compost in the past) if the leaves are not somewhat composted. This will prevent robbing the soil of nitrogen when those high-carbon leaves begin to decompose. Just this year, a new mulch called ÒSoil ConditionerÓ has become available that is made up of pine and hardwood fines (finely ground wood) and bark compost, and has sixteen essential macro and micronutrients added. Right now it is only available in 1.33 cubic foot bags, but will be available soon in 2 cubic foot bags. Its price appears competitive with bags of mushroom compost. I recommend it highly not only as a great mulch, but also as an organic addition to the soil. It works well in breaking up nasty clay soil. If you cannot find it, any pine- or bark-based soil conditioner that is mushroom compost free is preferred to using only mushroom compost. As for using mushroom compost as a mulch or soil amendment, we are starting to see major problems with its continued use on certain soils. If you have used it before, donÕt panic, but in my opinion you should not use it again without testing your soil and the mushroom compost, too. This caution applies to everyone except those who garden on low fertility, highly drained sandy soils. In that case, mushroom compost is an acceptable additive. Let me quickly summarize the problems I see with the overuse of mushroom compost:

1) Mushroom compost has a high alkalinity, which is not good for our soils here, which already run on the alkaline side. When the pH gets too high (too alkaline), the nutrient availability to the plants is decreased.

2) Mushroom compost has a high phosphorus content which ties up micronutrients, making them unavailable to the plants.

3) Mushroom compost has a high salt content which adversely affects nutrient and water uptake.

4) Mushroom compost clogs the soil pores that are essential for good soil structure, and it is that good structure which allows for increased oxygen and water flow into the soil.

5) Mushroom compost upsets the nutrient balance in the soil.

6) Mushroom compost offers minimal thermal protection, making it an ineffective mulch.

iii

Toni Vaughan is head gardener at Blackberry Farm-Pioneer Village, in Aurora, IL. You may contact her at 3020 W. Galena Blvd. Aurora, Il. 60506 or AntoinettePVaughan @ avenew.com.

The Weedpatch Gazette
PO Box 339
Richmond, IL. 60071-0339
(815) 678-6005 (phone and fax)
email: weedpatch@rsg.org
©1998-1999 R. Lopat Communications. All rights reserved.
Reprint with permission only.

Site Design and Promotion by:
Adastra Designs