Gardening in Clay Soil

What is Clay Soil?

gardening in clay soil
To begin, let’s define soil. All soil is a combination of mineral particles, organic matter, water, and air. The mineral particles come from weathered and dissolved rock matter, and the organic components come from decayed plant and animal materials. Air and water circulate within the spaces between the solid mineral and organic particles.

The relative size of the mineral particles determines the type of soil that you have. If the majority of the mineral particles are very small, you have clay soil. At the other end of the spectrum, soil that consists of mainly larger mineral particles is known as sandy soil. You can actually see individual sand particles; but, individual clay particles are so small – 1,000 times smaller – that they cannot be seen by the naked eye.

The very small particles of clay stick together tightly, reducing the soil’s ability to drain well. Wet clay sticks to everything; dry clay can be extremely hard to cultivate. The good news is that clay soil is usually high in nutrients; but, the physical characteristics are not conducive to productive and enjoyable gardening.

How to Improve Clay Soil

The goal is to create and maintain soil that is easy to cultivate and that is a good environment for growing plants. You can improve the texture and structure of clay soil by adding sand and compost. Sand will quickly improve the texture by separating some of the smaller mineral particles and allowing more openings for air and water circulation.

Soil structure is determined by how well the soil particles stick together to form larger groups. The best structure is when soil particles combine to form small round shapes known as crumbs. Good crumb formation, like good texture, allows good root development and relatively free movement of air and water. Compost will improve the structure by providing humus, which builds more loosely compacted soil crumbs. And, compost will significantly boost your soil’s nutrition level and will help plants resist disease.
Mantis Deluxe 9" Tiller/Cultivator

Adding Sand to Clay Soil

Add sand to clay soil when the soil is moist, but not too soggy. Use a rototiller (such as a Mantis Tiller) to till the sand into the top 8 to 12 inches of the soil. Of course, sand will add volume to your soil; if you’re working in a garden bed that cannot be expanded in height or width, you may need to remove some of the clay soil before you begin the amendment process. Removed clay soil can be mixed with sand to provide filler for other areas of your lawn and gardens, or you can use the soil mix to start or supplement your compost pile. Soil that is very heavy in clay content will require a lot of sand to noticeably change its texture; you may need to add 3 or 4 inches of sand for extremely heavy clay soil. Your Mantis Tiller will make this process very easy, especially if the soil is a little moist. Of course, any amount of sand that you add will improve the texture.

Customer Testimonial

A BIG Thank You!! Thank you for making such a GREAT product. I was totally impressed with the way the Mantis tiller went through my hard clay ground. I have been wanting to put in a small garden in my back yard for sometime now,but I didn’t want to spend a lot of money on one of those big tillers. The Mantis tiller was the perfect answer for me. Thanks again for making such a GREAT product!!”

Roger M. Ohio
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Adding Compost to Clay Soil

You can significantly improve the structure of clay soil by adding compost. Compost will improve the soil’s ability to form crumbs, improve the soil’s fertility, and improve the soil’s tilth. You simply cannot add too much compost to your soil.

If you don’t have a compost pile or bin, now is the time to build or buy one. There is simply nothing better for the long term health of your garden soil than compost. You can start composting at any time of the year. The best ingredient for great compost is brown, dry, shredded leaves. Make a mental note to collect as many dry leaves this autumn as you can comfortably store or add to your compost. Finely shredded dry leaves make a great vegetable garden mulch, too. They will help the soil retain moisture and will decompose over time and improve the soil’s tilth and fertility.
If you’re adding sand to improve your clay soil’s texture, you can add compost at the same time. Compost will also improve your soil’s structure and tilth. Of course, you can use compost to improve your soil and to feed your flower and vegetable plants throughout the season. Remember that compost is not mulch. While it will help your soil retain moisture (as mulch also does), it will not suppress weed growth. Indeed, compost is the ideal growing medium for weeds as well as flowers and vegetables. So, add a mulch of shredded dry leaves and/or grass clippings to help suppress weed growth. And, of course, the mulch will decompose over time and add to your soil’s fertility and tilth.

How to Know When Your Soil Texture and Structure are Good

Your soil’s texture and structure are good when a handful of moist soil can form a ball that is easily crumbled. If you can’t form a ball of moist soil, it is probably too sandy. You’ll need to add more compost. If you can form a sticky ball that doesn’t easily crumble, it is likely that your soil has too much clay content. You’ll need to continue to add more sand.

Soil can always be improved; and, your Mantis Tiller makes soil improvement easier. Once you’ve achieved the right soil texture, the best way to continue to improve and maintain good soil is to add compost before, during, and after the growing seasons.



  1. I’m afraid that I must disagree with your advice to add sand to heavy clay soil. In most cases, all you will do is create a form of concrete that is even more difficult for plant roots. Clay soil needs the addition of organic material. Period.

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