How to Amend Clay Soil for Healthier Gardens and Happier Plants: Your Garden Will Thank You
Clay soil can be hard to garden in, but you don't have to settle! Amending clay soil with organic matter can make drastic improvements. Learn how!
Amy Draiss
Does your garden soil stick to your shoes? Does it get extremely hard when it dries, even crackling sometimes? Those are characteristics of clay soil.
Clay soil has a bad rap for gardeners, but there is nothing inherently bad about it. However, when it comes to plants growing in it, its thick, compacted nature prevents water from draining through, and also prevents roots from penetrating deeply into the ground.
But that didn't make it a death knell for a garden. Mixed clay soil can be workable as is sometimes, and you can improve garden soil with amendments before you put in seeds. You can fix clay soil drainage and loosen it up to permit plants to grow there. Read on for information about how to improve clay soil sufficiently to allow plants to grow.
Article continues belowWhy Does Clay Soil Need Improving?
Three types of particles make up soil: sand, silt, and clay. Clay particles are the smallest particles, so small that they can easily get clumped together and compacted. This makes it difficult for new roots to grow into the soil, making it impossible to have healthy, vibrant flowers or vegetables.
The same applies to attempting to grow turf on clay. Lawns planted on unamended clay soils do not thrive; these lawns are difficult to irrigate and the grass will remain shallow rooted.
You can determine what type of soil you have with a few types of soil tests. An easy at-home test to determine what your soil is made of is the mason jar soil texture test. Put a sample of your soil in a jar with water and dish soap, then give it a shake. When the mixture settles, you will see sand and silt at the bottom, cloudy clay up top, with peat above that.
How to Improve Clay Soil
The “magic wand” for dealing with clay soil is organic matter. Adding organic matter to the clay soil helps by causing the clay particles to form crumbs or granules. Adding organic matter into clay soil, in short, improves the soil structure. There are two main ways of doing this: digging in organic matter, or adding organic mulch. You can also use cover crops to create an in-place mulch source.
Dig In Organic Matter
Adding organic matter to clay soil starts with selecting the organic matter to add. Prefer fast-decaying matter, like animal manure (leached of salt), green plant material, compost, and leaf mold. Pass up straw and other slowly decaying organic matter.
To amend clay garden soil with organic matter, layer your selected organic matter on the soil. Add between 1 and 4 inches, then use the garden fork to work this matter in. Try to blend in into the top six inches of clay soil over the planting area. This is a practice that should be repeated annually. Don't have time to wait for compost to be ready? You can find organic compost from Back to the Roots at the Home Depot.
How to improve clay soil for lawns? For lawns growing on clay soil, dig in the organic matter while aerating the soil. Use an aerifier that takes out soil cores to a depth of some 4 inches. Then use organic matter to fill those holes. You can rent an aerator from your local hardware store or purchase a manual core aerator from Garden Weasel on Amazon.
Add Organic Mulch
The other way to add organic material is to simply layer it on top of the clay soil and let nature do the digging in. Some experts recommend using the organic matter as a mulch, and layer a few inches on clay garden beds without mixing them in at all. They work as all mulch does, forming a “blanket” of protection that holds water in the soil and limits soil hardening. In addition, the organic matter attracts earthworms and other insects that help transform the matter into nutrients and aggregate soil particles. You can find dye-free organic mulch from Miracle-Gro at the Home Depot.
Growing Cover Crops
What are cover crops? These are actual crops you plant in a garden as a type of living mulch. Using cover crops to improve clay soil for vegetable gardening is a great idea. These cover crops - like clover, annual ryegrass, or oats - grow thick and fast, stopping weeds from invading and combating erosion.
For clay soils, you can use these cover crops as green manure by turning them into the soil. Wait until the crops are mature but before they flower to fork them into the top of the clay soil. Like organic mulch, cover crops will improve soil structure and add nutrients too.
Some common cover crops include clovers, a fast growing crop fixes nitrogen in the soil. Some clovers will go dormant in the winter and start growing again in spring. Experts recommend ‘Ladino’ as a great cover crop, a giant white clover. You can find a bag of 'Ladino' white clover seeds from Amazon.
Another popular cover crop is also an edible crop: legumes like peas or beans. These crops also fix nitrogen but have the added bonus that you can harvest the edible pods before turning the plants over.
How to Avoid Soil Compaction
The priority when you have clay soil is to prevent soil compaction, the crunching together of the tiny particles of clay. Clay soil is very susceptible to compaction. When these clay particles are packed tight together, the result is poor drainage which leads to the soil turning into clods when you. If you try to till compacted clay soil, expect clumping that will block the tillers.
The solution? Don’t work the soil at all until you’ve amended it. Don’t walk on it. Keep off it especially when it is wet. If you feel you must work unamended clay, dig it out with a spading fork, not a shovel. Turn over the soil and pull the clumps apart with the fork and move them to the top of the soil.
This will allow nature to help by drying out those clods with the sunshine and wind. Dry clods can be crumbled, lightly sprayed with the hose, then raked to reduce them to small pieces. This will break up most of the large, wet clods and allow you to begin the work of loosening compacted soil.
How Using Raised Beds Can Help
For those who don’t want to or can’t amend their clay soil, there is an easier fix. It’s called raised bed gardening. If you build raised beds above the soil, you don’t have to worry about your clay content. Simply fill the beds with great soil and plant your flowers or veggies there. Our gardening editors have been obsessed with the Vego raised garden bed kits for years. Senior Editor Liz has had a collection of beds that has been going strong for half a decade with no problems or deterioration. You can find Vego raised bed kits from Amazon now, too.
Shop Clay Soil Amendment Essentials
This organic compost from a small business will add nutrients and better structure to your garden soil.
This heavy duty garden cart makes it easy to haul around soil amendments. Lift the end to easily tip out its contents right where you want them.
Vego Garden's raised bed kits are favorites of our editors. When clay gets you down, raise up. No clay here!
Frequently Asked Questions
How Do You Break Down Clay Soil Fast?
Sadly, amending clay soil is not a rapid procedure. It may take a few years of adding organic content before it is ready to plant.
What is the Best Product to Improve Clay Soil?
The only way to amend clay soil is by repeatedly adding organic matter to the soil. There is no one “best product” that will change the soil structure.
