Because many species overwinter as adults, they are able to keep pest populations in your garden under control by cutting down on adult pest species before they reproduce.
Squash bugs can overwinter in wood mulch and wood boards, so eliminating potential habitats can help rid your landscape of next year's pests.
Iris should also be cut back, because the eggs of iris borers overwinter on iris leaves and attack the rhizomes in the spring.
Spinach, Swiss chard and kale can be sown in the fall garden and harvested throughout the winter or left to overwinter.
Disease microorganisms can also overwinter on the surface of stakes, tomato cages, trellises, and other garden items.
The fungi and bacteria that cause so many problems can overwinter on contaminated stems and roots.