Clay is a type of soil that packs tightly and does not allow water in. While most plants find this type of soil impossible for growth because of its water-tight nature, humans have found a number of uses for the substance. Clay has a number of interesting characteristics that set it apart from other, more conventional soil types.
Adding Sand to Clay
Many would-be gardeners who have claylike soil in their backyard attempt conversion of the soil by adding other soil types such as loam, mulch or peaty soil to increase moisture, aerate the clay and help it drain better. While sand drains the best out of all soil types, adding sand to claylike soil may make whatever's planted there stick around permanently, according to the Colorado State University Extension. This is because adding sand to clay makes a material much the consistency and hardness of concrete. This natural cement absorbs water better but is sticky and stops nutrients from getting through. The result is dead plants that are almost impossible to pry from the ground.
While most of the clay found in yards or by streams is unusable even as garden soil, terramin, or living clay, is actually good enough to eat. This type of clay develops near desert regions and features high levels of minerals such as calcium, as well as trace minerals that are used in the production of enzymes. Although this type of clay is readily assimilated by the body, many proprietors have repackaged it into teas and pills, marketing it as a supplement.
Just because the backyard is full of clay soil doesn't mean you cannot raise a garden there. Several plants have evolved to thrive in clay. These plants include tickseed, which produces bright yellow asterlike flowers; mealycup sage, which blooms with bright plumes of tiny purple flowers; and spotted jewelweed, a thin-stemmed plant whose flower curls into an orchid shape. These plants usually have roots that grow toward the surface and may require wind protection.
Improving for Gardens
Although adding sand is not a good idea for improving clay, the soil type can be improved to grow other plants. Adding organic matter such as compost and mulch helps break up the fine grains of clay that pack tightly while letting in enough moisture to unlock some of the many vitamins and minerals found in clay soil. Improved clay soil often has more necessary nutrients for plant development than soil that experiences regular drainage.