When preparing the ground for a garden it is a good idea to get the soil tested for ph levels. Depending on the type of garden different plants flourish in different soil types. Some soils are more acidic than others so it is important to find out what the soil type is in the area that is the planned garden location.
For vegetable gardens, PH can be very important. However, sunlight and PH is not the only issue to be concerned with for a thriving vegetable garden.You can find a quick rundown here The soil type is also important as well. Certain soils have more clay deposits and make for poor gardening due to a lack of water absorption levels. When this is the case, it is advisable to relocate the gardening area to more suitable soil. A well draining soil is best so that when it rains water does not pool around plants and drown them.
Flower gardens on the other hand or simple ground cover gardens can survive in rocky and clay filled soils a little easier, but most plants have a difficult time in this type of soil. In these cases it is advisable to dilute the clay significantly with more well balanced soil types for proper plant growth.