There’s a time period in spring and fall when the soil is just perfect for rototilling or spading. The soil works up beautifully, leaving the planting beds mellow and picture-perfect for vegetable gardening and planting annual and perennial flower beds. I often joke that with heavy, clay-type soil that perfect time period is about one hour in spring and another hour in fall. If you’re busy that day, you’re out of soil luck.
If soil is tilled at the wrong time, it’s structure can be ruined. Heavy clay soil can form rock-hard lumps if tilled or spaded when it’s too wet. It takes a long time for those to break down, and planting can be adversely affected.
There’s an easy way to tell if soil is just the right stage. It’s the squeeze test. Take a handful of soil and squeeze it tightly in the palm of your hand. When you open your hand, if the soil ball crumbles apart easily, it’s good to go. If the soil stays in a sticky mudball in your hand, the soil would be adversely affected by rototilling or spading. Wait a few days, and then test again. Both spring and fall are great times to improve soil by adding organic matter. Two inches of compost, manure, dried grass clippings or peatmoss can be spread over the soil and tilled in. Organic material helps heavy clay soil become more mellow and workable. Organic material improves light, sandy soil by increasing its moisture-holding capacity.