Applying mulch continued

by Mark Amara Grant-Adams Master Gardener
| November 16, 2018 2:00 AM

Continued from last week

Now that you know a little more about what mulch is, let’s see how mulching leaves is good when applied this time of year. Here we are in fall with mountains of leaves to deal with. Collecting it is sometimes a challenge. Whatever way it is collected, there are many benefits to keeping and using it.

Spreading leaf mulch helps smother weeds, reduces soil and water runoff, and increases water retention the following year. Laying materials down 2-4 inches or more in thickness helps keep weeds from surfacing assuming the ground is relatively weed-free to start with. If the layer is too thick it will repel water, decompose more slowly, and can actually smother young desirable annuals. Always keep mulches several inches away from trunks of trees and shrubs and stems of herbaceous plants to help keep excessive moisture away from these interfaces (which can deter rots and other diseases). Remember that mulching does not control weeds indefinitely and materials must be reapplied for continuing benefits.

Around perennial trees and shrubs, putting leaves higher and deeper up to 3-6 inches is of benefit. Perennial weeds like field bindweed, horsetail, or quack grass are not controlled by mulching and will have to be pulled or dug up by hand or might even require some kind of chemical removal both before and after mulch is applied. Using leaves in walkways or between plant rows are also effective ways to control weeds and add organic nutrients.

All plant mulches have some nutrient value in terms of nitrogen, phosphorus, potassium, calcium and magnesium and can provide 50-80 percent of the fertilizer plants need each season. It is always best to soil test at least every few years unless specific fertilizer needs are known.

The addition of biodegradable plant mulches is good in that they stimulate microbial activity which in turn helps with rooting, decomposition, residue breakdown which ultimately releases nutrients into the soil. As leaves break down, they also provide food for earthworms which helps aerate the soil. Most leaves are a good source of potassium and often have pH from 6-7.5. The potential for increased biological activity in the soil can help improve biodiversity and help prevent plant diseases.