Clay garden soil is not all bad. Clay soil is often rich and fertile and may be quite good for certain kinds of plants. In some areas, clay is much more common than silty soil, sand or loam and people make do for the most part.
Unfortunately, clay has a few major problems. The first is poor drainage. The tiny particles of clay based soil don’t let water drain through, and become a soggy mess when it rains. A related problem is poor oxygenation.
There are few air pockets in clay, which means the roots don’t get the air they need. Clay is also too dense for good root penetration. Because of all of these issues, amending clay soil is better than using it as it is.
Unfortunately, there is no one ingredient you can add to your soil to make it into healthy loam soil. Clay soil conditioners will help, but they won’t entirely fix the problem.
Coarse sand can also help, as can manure and compost. The key is to add a variety of materials to your clay soil, fertilize frequently and lay fresh layers of compost every year.
Amending clay soil is a slow and time consuming process, and you have to be willing to wait if you want to do it right.
Of course, an easy alternative to amending clay soil is to add a new layer of surface soil. Rather than mixing the new soil into the existing clay, you add it on top of the surface. This can be initially expensive, but can really pay off in the long run if you care for your new soil layer properly.
Use organic fertilizer and compost and prevent erosion from washing it away and you will be able to continuously build up your healthy topsoil layer.
The process is also somewhat easier than amending clay soil, since you don’t have to mix it in. And effectively, it accomplishes the same goal: giving you healthy, well-drained soil to grow your plants in.
The downside is that adding new soil to the surface can be pricey, particularly if you want to add a few inches of topsoil to a large area. It might best to opt for combining the two techniques.
Add soil conditioners and other ingredients to the clay based soil you already have, then spread a thin layer of topsoil on top. This will dramatically improve your soil while decreasing your costs.