At some point each fall the vegetable garden is officially finished. The squash and pumpkins are harvested. The potatoes are dug. The carrots are left in the ground as long as possible to cold-sweeten. But before the ground freezes solid, the garden should be cleaned and tilled, rather than waiting until spring. Here’s why:
- Much of the old plant material should be raked off and disposed of, because insects and diseases tend to survive overwinter on old plant refuse in and around the soil. If the old plants are rototilled into the ground rather than being removed, there’s a greater chance that certain insects and diseases will be back again next spring to haunt the garden.
- Vegetable plants that are of special concern to remove are tomato, potato, winter squash, summer squash, cucumber, melons, and any plants whose foliage was blighted by disease. Many other plants are fine to till into the soil, including lettuce, old radish plants, spinach, cabbage, cauliflower, broccoli, beet tops, carrot tops, and anything that was healthy.
- Removing tomato and potato plants can help prevent blight next year by reducing the quantity of fungi and bacteria that overwinter right in the garden. These organisms can “blow in” on next year’s winds, but at least there are less surviving directly in the soil.
- Removing squash, pumpkin, cucumber and melon vines can help reduce mildew diseases and squash vine borer problems.
- The plants mentioned should be dispose of, rather than composting, because it’s sometimes uncertain whether compost will get “hot” enough to kill the organisms and insects.
- Rototilling the garden soil in fall helps improve the structure, tilth, and workability of the soil. “Working” the soil in fall exposes more of the ground to winter’s freezing and thawing, which is natures way of loosening heavy soil.
- Fall tilling helps kill insect and disease organisms that have entered the soil for winter survival by exposing them to the elements. Turning the soil over before the ground freezes exposes insects and diseases to colder temperatures, increasing the chance that they’ll winterkill instead of surviving.
- Fall tilling helps moisture penetrate more easily into the soil from late fall rains and spring snow melt, increasing the beneficial subsoil moisture.