Despite what many gardeners think, clay soil in the garden does not prohibit growing a good crop of vegetables. There is no need to spend a lot of money on soil amendments. Cruciferous vegetables, also known as brassicas or cole crops, will do well in clay soil. To prepare the garden for planting, dig down into the soil and turn it, crushing any large clods of dirt. Allow the turned soil to dry in the sun, then run a rake over it to level the surface.
Cabbage is a hardy vegetable that is very easy to grow, even in clay soil. There are early and late varieties of cabbage that can be grown in a garden. Early cabbage should be started indoors and then transplanted into the garden after the threat of frost has passed. Late cabbage should be started outdoors, during the heat of the summer, and will be ready to harvest in fall.
As a member of the cabbage family, the Brussels sprout is a hardy vegetable, but very slow-growing. It grows best in cool, even frosty weather in most areas in the United States. Brussels sprouts plants that are planted in late spring will be ready to harvest in the fall. Apply nitrogen fertilizer when your plants are 12 inches tall and water well during summer heat.
Broccoli is tolerant of clay soil, along with frost. Different varieties require different temperatures to grow well, so check with your cooperative extension to find out which varieties to grow in your area. Generally planted in the summer, broccoli needs time to develop prior to the cold weather. If planted after the heat dies down, it should be ready for harvest in late autumn or early winter.