How to Amend Unimproved Clay Soil

Get the ‘Dirt’ on Your Yard!

Chances are– if you are just about anywhere in Tarrant County– you are challenged with a yard full of ‘unimproved clay soil’. In some locations, you not only have that unimproved clay soil, but you also have more than your fair share of rocks and stones embedded in your dirt. (That’s the bad news!)
In most neighborhoods, everyone wants their yard to be the best! Look the healthiest. Be the most colorful. Have that yard that neighbors envy! (Except for that one neighbor a few yards down who just doesn’t seem to care. What’s up with that?)

The Bottom Line

Perhaps one of the most important things to realize is that your plants, shrubs, perennials and annuals will only be as good as your soil! You can buy the best looking plants at any nursery, but if you plant them in ‘bad’ soil, they will struggle and not perform to your expectations. Take a look at the soil your nursery plants are grown in while in the container. It is rich, almost light and airy. (Compare that soil to the dirt in your yard.) The container soil provides excellent drainage for watering while providing nutrients for plant growth.

Why Clay is Challenging

Think of clay as a tiny spec of flour in comparison to a grain of rice. The tiny clay particles adhere to each other and restrict water from passing freely through the soil. The same holds true for air. Air and water are two things plants must have in order to grow and thrive—even underground. New root growth is essential to plant development and the dense clay makes it much more difficult for the tender new roots to grow.

Clay and Water

Because clay is so dense, it does not allow water to freely penetrate the surface. Compare clay to concrete. If you put your sprinkler in your driveway and turn it on, the water will wet the surface and run downhill to the lowest spot. Perhaps not to that extreme, but you get the idea of what happens when you water your lawn and shrubs when planted in clay soil.
Clay also holds water which can damage your plant’s root system. (You can actually drown a plant with too much water and not enough drainage.) Think about a clay pot, only without a drainage hole. That’s what you get when you dig a hole in unimproved clay soil and plant your shrubs, perennials and annuals. The water collects in the ‘underground clay pot’ and creates a pool of water which can damage the root system and possibly kill the plant.

Hope Springs Eternal!

All is not lost! There is no need to resort to purchasing plastic plants as a source for greenery and color in your yard. Here are two key words for you: soil amendments! Decomposed pine bark, manure, organic compost, bagged garden soil, peat moss, even grass clipping and leaves from your trees in the fall can be added to improve your soil. When these soil amendments are incorporated into your clay soil, they break up the densely compacted clay particles and provide drainage and air pockets for healthy new root growth.
Clay soil is typically alkaline in composition and different soil amendments can assist in creating a more balanced soil. For more acidic soil, more decomposed pine bark and peat moss will help tip that scale.

Mix the Ingredients!

Your goal is to create a new and improved soil for your plants in your new garden oasis! The good news is that you don’t have to dig to the Earth’s core. Set your sites on 12” deep. If you plan on creating a new flowerbed or garden area, amend the entire area. Once you take your shovel or fork and start turning the clay, remove the rocks in order to make room for the soil amendments. If rocks are not present, consider yourself lucky and one step ahead!
For best results, add 3” of decomposed pine bark, 3” of organic compost and 3” of bagged garden soil. Spread the soil amendments evenly across the freshly turned clay soil and begin the mixing process. The more you mix the amendments with the clay soil, the better your end result will be. For the best amending process, borrow, rent or buy a gas powered tiller. This will do the best job of breaking up the heavy clay particulates while thoroughly mixing the soil amendments into your newly created soil.
Once you are done, don’t worry if your amended garden area appears to be 6’ too tall! You have just mixed the soil and aerated the ground which will settle down after a rain or you have watered.

9-1-1 for Soil is 13-13-13

If you want to incorporate a fertilizer into your soil amendment mix, a 13-13-13 ratio is the best place to start. This provides 13% nitrogen, 13% phosphorous and 13% potassium for a well-rounded balance of nutrients. However, once you have amended your soil and planted your new shrubs, perennials and annuals, hold off on additional fertilizers and opt for a root stimulator application program instead.

Congratulations! You are almost done.

Now that you have transformed your ‘unimproved clay soil rock bed’ into a ‘growing media’ for the plants of your choice, determine how much sun or shade reaches the area and select the appropriate plants to please your needs! Your local nursery professionals will be happy to assist and offer suggestions based on your sun or shade areas. After that, top-dress your garden area with the mulch of your choice!
(Thinking of Spring Planting Projects? Winter is a great time to amend your soil! This gives your new soil time to settle in and get ready for fresh spring landscaping projects!)