Products For A Community Garden’s Soil

Q: We are organizing a community garden. Is it worth it to add to our soil a
product that has microbes and mycorrhizae? 

A: Products like this are heavily advertised. They promise great results using
beautiful photos. But my mission as a gardening educator is to stick with the
science that investigates the claims of garden products. Researchers at
Washington State University tested products that touted microbes and
mycorrhizae. Their research was reviewed by their peers in other parts of the
country. Their summary concluded that adding mycorrhizae to gardens is
“…generally ineffective and unnecessary….”. Your garden will be inoculated
with mycorrhizae naturally from falling leaves, compost, and wood chip
mulch. Avoid rototilling the beds after the first growing season. Tilling harms
the mycorrhizal environment. Many gardeners fervently believe in adding
microbes and mycorrhizae to soil. It’s a free country and you can spend your
money on whatever you like but you won’t find mycorrhizae additives in my
garden shed.