Clay soil is quite common in the United States and it can be quite a pain for gardeners to deal with too. For a couple of different reasons.
Reason #1: Clay soil retains quite a bit of moisture. Any plant that is susceptible to root rot is going to have trouble in heavy clay soil.
Reason #2: Clay particles are the smallest particles in soil. Therefore, clay soil is incredibly dense due to the lack of space between particles. This prevents air flow around roots, which is a problem for many plants.
Reason #3: Clay is highly alkaline. This may not be a problem for some plants that enjoy alkaline soil, but any plant that requires acidic soil has an uphill battle when planted in clay soil. This list includes Azaleas, Camellias, Gardenias, Loropetalums, Rhododendrons, and Rabbiteye Blueberries.
That being said, clay soil isn’t all bad for gardeners. It’s extremely nutrient dense if you can get your plants to successfully take hold.
How do I know if I have Clay Soil?
There are usually a few dead giveaways.
When it rains, do you find your feet sinking in the ground? When you dig a hole, do the dirt clumps that you remove stay together after you dump them on the ground? These are two pretty common indicators of clay soil, however, there is also a pretty easy test as well.
Take a moist handful of your soil and squeeze it into a ball. Then, apply a bit of pressure to it with your finger. Does it crumble? Does it not make a ball in the first place? Or does it stay together and create a small depression where your finger was?
If it’s the latter, you likely have clay soil. Clay sticks together better than any other type of soil. If it’s clay, chances are you can poke, squeeze, twist, or toss that ball of soil and it won’t fall apart.
So now what do you do about it?
Fixing Clay Soil
“Fixing” may not be the best word to describe what you’re doing here. Technically, there’s nothing wrong with your soil, it’s just not ideal for gardening.
So dealing with clay soil takes a lot of work, unfortunately. BUT it is doable. The truth is that no matter what you do, you’ll need to do several rounds of it.
The easiest way to fix it is with a rotary tiller. Mix in 4-5 inches of organic matter such as compost, peat moss, fine bark, or even sawdust. This allows microorganisms to multiply and condition the soil. It improves drainage and encourages earthworms to do what they do best.
This is the best-case scenario, though. Most people don’t have access to a rotary tiller. So what you can do instead is top dress your soil with 3-4 inches of organic matter (once again, such as compost, peat moss, fine bark, and sawdust), and work it into the soil as best you can with a metal garden rake. This isn’t quite as efficient as the rotary tiller, but it will get the job done. Organic matter WILL make its way down, it just takes time.
You’ll need to do this about every year and every year your soil should improve a bit. We do recommend providing supplemental plant food for any plants in these areas that you’re trying to adjust. Microorganisms can make certain nutrients unavailable while they’re altering your soil, but they will be returned to the soil later in the year.
If you’re trying to grow a plant that prefers acidic soil during this time, test your soil’s pH. If it’s registering as alkaline, supplement it with elemental sulfur. This lowers the soil pH gradually over several months and it won’t damage your plant (as long as you apply the appropriate amount).
Oh, and one other thing to consider, NEVER ADD SAND. You can improve the drainage of non-clay soils by adding sand. But if you add sand to your clay soil, you will make your problems 100% worse. The clay will bind with the sand and become deeply reminiscent of concrete.
Final Thoughts on Clay Soil
It may seem unfair and time-consuming, but you can handle this gardening hurdle! Just remain consistent and keep supplementing that soil. Eventually you’ll have the type of soil that lets you do exactly what you want to do in your landscape.