How thick should I lay down mulch when there are already plants coming up from the ground?
Photo by Maddy Baker on Unsplash
About two inches is all that is needed, regardless of whether the plants are perennials or not. Any more than that could possibly delay or prevent plants from emerging. Since mulch does suppress weeds, obviously it could suppress plants as well.
More reasons not to put down more than a couple of inches in depth:
The mulch can develop mold and mildew
That will cause it to rot
Rotting or even good mulch can attract termites, and they like moisture
Thick mulch holds moisture too long (see above)
Too much moisture near plant bases or over roots can cause root rot
It’s a waste of money to over-mulch
It’s kind of like that children’s book, “If You Give a Mouse a Cookie.”