The Science Behind Winter Garden Prep
Putting the garden to bed for winter isn’t simply an exercise in neatness. There really is a scientific reason for the raking, straightening and gathering. And some chores you may reserve for spring—like tilling—can actually do more good when tackled in late fall and early winter.
Winter garden prep basically involves cleaning things up prior to the arrival of your region’s most intense winter weather. Timing varies based on where you garden. In colder regions like the Midwest and Northeast, these chores usually need to be wrapped up by early to mid-November—and sooner if you live in the coldest spots, like Minnesota or upstate New York. In regions with mild winters, garden clean up may be a December activity. Cleaning up the garden is usually timed with killing frosts, so that you’re removing frosted and spent plants. It’s also usually signaled by falling leaves.
The No. 1 reason for prepping the garden for winter is that it’s an easy way to disrupt pest and disease cycles. Maybe you never thought about it, but all the insects that drive you crazy during the growing season—cabbage loopers, squash vine borers, cucumber beetles, slugs, Japanese beetles, even tomato hornworms—have to go somewhere when winter arrives. Many common garden insect pests spend winter nestled into leaf litter or buried in soil anywhere from two to 10 inches deep. Other pests, like iris borers, viburnum leaf beetles, bagworms or tent caterpillars, survive winter as eggs. When you tackle winter garden prep, if you focus on eliminating insect hiding places and egg cases, you can beat next year’s pests before they get a chance to chew.
Like pests, many diseases can survive winter on infected pieces of plants. Fallen leaves, diseased stems and rotting fruit can all harbor disease particles. To curtail overwintering diseases, clip back leaves of perennials like peony, aster, hollyhock, bee balm and phlox. Many fungal diseases (think powdery mildew, rust, apple scab, tomato blights) enter a resting state known as a spore, which can survive cold temperatures. This is also why it’s not a good idea to add diseased plants to home compost piles. Most compost piles don’t heat up enough to kill disease spores. When cleaning up diseased plant material, bag it and put it out with the trash.
Many weeds act as hosts—sort of like a bus stop—for various plant pests and diseases. The pest or disease develops on the weed and that weed becomes a source of the problems in your garden. At the end of the growing season (and during it, frankly), it’s a great idea to pull weeds wherever you see them. Keep them out of the garden—and don’t forget to scout nearby growing areas, such as beneath shrubs, along fence edges or in garden paths. Removing weeds can stop many pest and disease problems.