Clay soil is a specific type of regional soil known for its fine texture, high rate of moisture retention, and low rate of air flow. It can also present drainage challenges in your garden, and it can take longer for water to soak all the way through it than with other types of soil. Clay soil is rich in nutrients, and there are many types of plants that will grow well in clay soil; the key is often taking steps to increase the infiltration rate.
These flowers are primarily found in more humid climates, and the most common factor that needs attention is that they can dehydrate even if watered regularly. To prevent this from happening with your clay soil, mix in pieces of tree bark, tree mulch, or other organic compost before planting. You can also add pea gravel, which is effective in adding more spaces within the solid clay for water to reach.
Black-eyed Susans are plants that naturally grow on the edges of ponds or lakes so they are used to high soil moisture content. As long as the clay soil is well turned and the correct amount of organic material is maintained, this should prevent these plants from completely drying out in the summer months.
Grape vines are especially responsive to clay soil that has been mixed with organic compost matter. It is not recommended to add potting soil to dug-out clay for grape vines because this can result in plant water logging. If the top level does not have enough airflow, water will build up on a compacted clay slab that is created under the grape vine. This is a special concern since grape vines' health effects start at the roots and can extend through a long vine.
The most effective solution to this problem is to mix in some pine bark hummus that should still make up only 25% of the original soil volume. It is not recommended to add any materials such as sand, wood chips, or mulch containing lime to clay soil. These are not nearly as effective, and lime has been found to restrict oxygen flow in the soil even further in some cases.
Yucca is a plant known for its tough roots, and it can survive much harsher environments than clay soil, including desert climates. It is a good idea to plant them in the spring, before the clay soil has had enough time to dry out. Dig a hole large enough for the roots plus extra space for them to spread out as the Yucca plant grows; this will prevent the roots from hitting an underground clay slab that is too hard to penetrate.
If you are facing clay soil that is overly solid and easily turns sticky with any rain, you may need to mulch the soil bed before adding any plants. Mixing in manufactured multipurpose compost found at any garden store will help correct this problem, creating a layer within the soil that gives growing roots plenty of breathing room. It also breaks up the solid clay and reduces the amount of sticky clay mud and plant water logging.