Clay soil exists in regions all over the United States. It is made up of tiny sized particles that tend to settle together. Because of this, small amounts of air pass through and it is slow to drain. Clay soil does have good moisture and nutrition retention, but for a home gardener it is almost impossible to work with. Some plants can do well in clay soil but most plants cannot survive.
A popular gardening myth is that sand should be added to clay soil to improve it and make it lighter. In reality, unless it is added in monumental and impractical amounts, this practice will turn clay soil into a rock hard, mortar like substance. Organic matter that adds soil life is a better choice to fundamentally change clay soil especially if you can add it once or twice per year for several years.
The best products we have used to break up and transform clay soil are the liquid bio-tiller, Penetrate, and Blend. Penetrate contains powerful ingredients that work together to break up hard, clay soils. It comes in two bottles; Bottle A contains food for aerobic bacteria while Bottle B contains live aerobic bacteria. The live bacteria and other ingredients work together to break apart hard soil and allow air and moisture to circulate to plant roots. Penetrate in conjunction with Blend is the fastest way to improve drainage and turn hard clay into dark, crumbly soil that is easy to work with.
Penetrate is easy to apply; simply mix the two bottles together in water and spray right on top of the soil using a hose end sprayer, backpack sprayer, or watering can. Penetrate can also be found in the Clay & Hard Soil Kit, which is the fastest and most aggressive way to amend clay soil. The Clay & Hard Soil Kit includes 4 times the amount of Penetrate we would normally recommend along with Optimize, Maximize, and Nourish-Biosol (The three products found in Blend). The organic products in this kit introduce all levels of microbes (bacteria, fungi, protozoa) that digest thatch and dead leaves, creating food for beneficial microbes. It feeds the beneficial micro-organisms in your soil so that it can store and release nutrients and water plants much more efficiently. It also provides natural organic nutrients for plants to use right away and reduces pests and diseases.