Timing is everything when it comes to mulching, which is spreading mostly organic matter over the surface of soil to protect and improve its condition. But doing it too early could create problems, as could doing it too late. When's the right time to mulch your garden? Here, we break it all down.
When to Mulch
The right time to mulch a garden is dependent on what type of plant material you are mulching and the weather conditions, says Kurt Morrell, the A.P. Farm Associate Vice President for Landscape Operations at the New York Botanical Garden. In general, mid- to late spring is mulching season—that's when the soil is warming up from the freezing temperatures it experienced all winter. Doing it too early will slow down the warming process, which the soil needs to do its job. Morrell also warns against mulching late in the fall. "This can insulate the ground and prevent plant dormancy," a much-needed hibernation that helps plants survive the cold winter months.
Gardeners rely on mulching because it helps soil stay moist and weed-free, just two of its many benefits. But there are precautions. "Avoid mulching tender perennials, as they are breaking dormancy early in the spring," says Morrell. The best time to mulch perennials—flowers that come back each year, such as hostas and peonies—is when they are completely dormant or after they have hardened.
Some gardeners believe in winter mulching for its damage control abilities to those parts of a plant that are above the ground. But again, timing counts. "Mulching newly-planted plants after the ground has frozen in early winter may prevent the plant from heaving during the freezing-thawing cycle over winter," says Morrell. (Heaving happens when the pressure that is created from alternating freezing and thawing conditions lifts the soil and plants up and out of the ground. Remove mulch gradually as the ground and temperatures warm; removing it all at once could startle the plant.)
Don't over mulch—in the case of flowers, more is not better. If you lay down a too-thick layer, seedlings may not be able to access it. When it gets lower than two inches, replenish with another inch of mulch.