Answer: Improving soil usually takes time, so don't expect instant results. The best thing you can do is add organic matter such as compost to increase pore spaces in the soil. This will allow it to hold more air, drain better and therefore encourage better root growth. Sources of organic matter can include compost, rotted down autumn leaves, well aged stable manure and bedding, wood chips, broken down mulch, and so on. Additional sources over time include growing cover crops and using an organic mulch which will break down slowly over time and feed the soil.
Also run some basic soil tests to check the fertility and soil pH. This will tell you if you need to fertilize and/or add lime. Your local county extension should be able to help you with the testing and interpreting the results. They may be able to advise you of locally available materials for soil amendment and should also be able to tell you if it would be helpful in this case to add a small amount of coarse sand or fine grit to the planting areas.
Finally, consider making raised beds for your planting areas. Many times a rise of just a few inches can make the difference between success and failure. You can use an informal sloped edge or install walls for the beds, as you prefer.
Q&A Library Searching Tips