Clay soil is hard and unyielding when dry and turns into sticky clumps of dirt when wet. There's little space between particles in clay soil, and this results in poor drainage. It also means plant roots have a difficult time penetrating the soil, and so the plants may fail to thrive. If you want to loosen the clay soil before planting your garden, you can turn the soil, add amendments and treat the soil for long-term health.
Spray the area with a garden hose in the evening. Make the ground wet enough that you break up the crusty surface, but not so wet the water puddles on the soil surface.
Use a shovel to break up the top of the soil the next morning. Insert the shovel a few inches and loosen up the dirt. Do this every few inches throughout the garden area.
Use a rototiller to aerate the soil after breaking it up with the shovel. A rototiller is a machine with circular blades on the front. The blades have teeth that dig into the soil and break it. A rototiller will break up the soil to a depth of approximately 2 to 3 inches.
Add a 1-inch layer of granulized gypsum over the soil surface and spray lightly with water. Gypsum is made up of calcium sulphate; it is the same organic material used in making drywall. Allow the soil to dry overnight.
Add a 2- to 3-inch layer of compost on top of the soil and gypsum the next morning. Use your shovel to turn the compost, along with the gypsum, into the aerated soil. Water lightly and then allow to dry overnight.
Add another layer of compost to the soil and work it in with a shovel. Continue the process of working in compost until you can push your shovel into the soil while it is damp and the soil does not clump. This may take several days or, depending on the original condition of your soil, 2 to 3 weeks.
Begin planting after your clay soil has been loosened and amended. Throughout the growing season, mulch around your plants to aid in keeping the soil loose and providing nutrients for the plants.
Add a layer of gypsum to the surface of the soil at the end of the growing season, followed by a layer of compost. Work the compost and gypsum into the soil.
Continue to add gypsum to the soil yearly for 3 years. The gypsum will organically aerate the soil. Continue to amend the soil with compost every growing season, and mulch after planting. This will keep the clay soil loosened for better drainage and good root growth on your plants.