UNIVERSITY PARK, Pa. – Spending a few autumn afternoons completing outdoor chores can prepare your lawn and garden for the coming snowfall and a healthy spring. "You can diminish your problems with insects, weed and disease problems next spring if you take some time out before it snows to clean up your yard and garden," said Jim Sellmer, associate professor of ornamental horticulture in Penn State's College of Agricultural Sciences.
While it might be tempting to put away the lawnmower as the air gets colder, "make sure you keep your lawn mowed until the grass stops growing," said Sellmer.
"Taller grass can get matted under the snow, which can lead to snow mold, which leaves circular white patches on your lawn. If snow mold is excessive, reseeding may be necessary."
Weeding a garden or lawn may not always be fun, but taking a little time out in the fall "prevents the possibility of weeds seeding," said Sellmer. "Pulling one weed in the fall can save you from hundreds of weeds appearing in the spring. Taking care of weeding in the fall also will lessen the chances of harboring insects over the winter."
An area of concern for gardeners is the hardiness of insect eggs and plant diseases caused by bacteria and fungi over the winter months. "Spring is the time plants are most at risk for pests and diseases," Sellmer said. "If you simply clear away dead plants and fallen leaves, you can eliminate many of these problems. Most of this debris can be composted unless it is severely infected."
An easy way to combat these pests and diseases is to turn garden soil to quicken decomposition of plant debris and prevent survival of insects, bacteria and fungi. In addition to killing off pests, turning the soil also adds organic matter to the garden, Sellmer said. Don't be discouraged if weeds pop back up after purging your garden since most weeds germinate during the autumn months. "Regardless of how carefully you weed, some seeds will fall," he said. "Cover your garden with 2 inches of mulch to discourage seeds from germinating in the spring."
For perennial weeds, which go dormant during the winter, Sellmer suggests a nonresidual post-emergence herbicide to kill the perennial weeds now and thus prevent regrowth in the spring. "Your local garden center will have information as to which herbicide is best for your weed problem, so be sure to read the label carefully so you know exactly what you’re getting," he said. "Be careful not to spray the herbicide near any plants you want to keep, like perennials."
Weeds and insects are not the only pests to protect your garden from; weather and animals provide their own problems. "To protect your trees and shrubs from deer, rabbits and rodents, you can wrap them in plastic or woven wire mesh," said Sellmer. "Support the branches of your plants with stakes if snow and ice buildup is a concern.
"By removing dead twigs and branches, there is less of a worry for breakage when ice and snow build up, though you should save major pruning for the spring. Wounds from pruning will draw away moisture during the winter months on any tree."
Spreading 2 to 3 inches of mulch over the root systems of trees helps to keep in moisture during the winter but Sellmer warns against mulching any closer than 6 inches from the trunk. "Mulching up around the trunk of a tree is a mistake. Rodents can burrow under the mulch and chew off the bark of a tree. Mulch also gathers moisture and can cause the bark to rot, which can kill the tree."
If you choose to plant any new trees or perennials this fall, make sure to continue watering them until the ground freezes. "Watering newly planted trees and shrubs is crucial for root system formation to sustain them during the winter months. Make sure you don't keep the soil saturated, though, as it will kill a developing root system."
Finally, autumn is a perfect time to get your soil tested. "Nutrients such as lime and phosphorous can be worked into the soil in the fall if you find deficiencies,” says Sellmer. “It is best to work half the lime in during the fall and half in the spring."
Local Penn State Cooperative Extension offices sell soil test kits which give a chemical analysis of the soil along with lime and fertilizer recommendations.