The lone voice of horticultural reason

Don’t put mulch down around perennials until June 15.

Short and sweet, the rule is, in the north, wait until June 15. This is one of many facets of gardening in the north that is always ignored by national gardening magazines and books. They tell you to put a nice one- to two-inch layer of cocoa bean shells, or dried grass, shredded leaves, peanut husks, whatever, down around your plants “in the spring.” Mulch keeps weeds down, keeps roots cool, and curtails evaporation so we don’t have to water so often.

But this is the north. We need to wait until June 15 because it takes that long for the sun to get high and hot enough to sterilize our soil. Powdery mildew and a dozen other funguses aren’t killed by our cold winters. They remain atop the soil. You want that soil blasted by sun before you mulch for the summer.

I know it’s tempting to mulch right now, when perennials are small and it’s easy to get the mulch down on the soil surrounding the plants. Sorry. June 15.

Don Engebretson
The Renegade Gardener