You remember the anecdote about the thermos, you put a hot liquid in it, it
keeps it hot, put in a cold liquid, it keeps it cold. HOW DOES IT KNOW WHAT TO
Wood mulch, it *keeps weeds from growing*. So you spread the recommended 3-4
inches to keep the weeds down, but any perennial under the mulch will return.
HOW DOES IT KNOW WHAT TO DO???
Weeds growing up from under the mulch can grow just as the perennials
can grow, more or less (depending on the type of mulch, the plants in
question, and a myriad of other variables). In some cases you'll need to
pull away some mulch in spring or else some perennials won't come up. In
other cases weeds may come up despite heavy mulch. You are right. The
mulch doesn't know what it's supposed to stop, and what it's supposed to
let come up.
As for weed control, what the mulch does is keep weed seeds away from
the soil. Those that do germinate will germinate in the loose mulch, and
thus be easier to pull.
Some seeds need sunlight to germinate (grass for example) so if they are
covered or fall through the mulch they lay there til they rot. It is often
recommended that you pull mulch away from the root crowns of trees and
shrubs so that they don't rot or insects and mice don't do damage. Shade
perennials and many bulbs evolved to come up through a layer of leaves
(mulch) and are not damaged by the decaying leaves or the lack of light once
established (coming out of dormancy whether they reach the light through
inches of soil or inches of soil and mulch doesn't matter). Also as they
push their way up they are pushing the leaves away from the base of the
plant. Every year I gather all the leaves I can from the street and throw
them into my shade area. I never worry about any shade perennial coming up.
I on occasion will pull a leaf off of a hosta leaf that it is deforming.
The perennial is an established plant; the weed is typically
germinating from seed. It's the struggling up through 3-4 inches
of mulch, trying to establish a root system and grow leaves at
the same time that does in the weeds.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.