You can grow grass in clay soil if you use these methods to improve soil drainage and overall soil health.
Growing grass in clay soil can be done if you use a variety of methods to improve the clay soil. These methods include adding organics and soil conditioners as well as mechanical methods such as core aerating and top dressing.
If you’re serious about improving your clay soil then you need to use most of, if not all of these methods. It may take several repeat efforts to build soil structure that is a healthy mix of sand, silt, clay, minerals, and organic matter that make up the ideal soil, or ‘loam’, for growing a healthy lawn.
Improving Clay Soil
Of the three particle sizes, sand, silt, and clay, the smallest is clay. This makes clay very dense which is why clay lawns are poor drainage lawns. Poor drainage lawns can drown grass roots and prevent nutrient intake. The only way to prevent your grass growing in clay from ultimately dying is to improve the clay soil using a combination of these methods:
1. Core Aeration
If you’re trying to improve clay soil in an existing lawn then Core Aerating is definitely where you need to start. A core aerator is a machine that pulls cores, several inches long, out of your lawn. Most equipment rental places have these machines available for rent.
Core aerating is where this process begins, although, by itself it won’t do much to solve your compacted soil problem. It’s simply the first step you have to take before you can get organic matter and soil amendments into your soil. After core aerating continue by using the soil amendment strategies below.
2. Top Dressing With Compost
After core aerating, top dress your lawn with compost. Core aeration combined with top dressing with compost is by far the best two things you can do to improve clay soil problems in an existing lawn. If you are only going to take two steps to fix your clay problems, then choose core aeration and top dressing.
The way it works is simple. The voids that are left over after core aerating get filled with compost. The compost also gets raked all over the surface of your lawn about a 1/4” thick. This is the best way to introduce a ton of organic matter into your soil.
If you have a cool season lawn, then after top dressing, take the next step and apply a starter fertilizer and a light seeding with a quality seed (more on seed below).
If you have a warm season lawn then you shouldn’t need to seed since most warm season lawns spread via rhizomes and/or stolon’s and will naturally fill in. Check out more on top dressing your lawn here: Top Dressing Lawn: Benefits and Advice.
3. Liquid Aeration
Chances are you’ve heard of core aeration, but you may not have heard of liquid aeration. Liquid aeration is a liquid solution that helps loosen up soil so water and nutrients can penetrate deeper into the soil. It is similar to core aeration only in core aeration sections of grass are physically removed from your lawn. In liquid aeration, instead of removing cores from your lawn, the solution works by breaking up dense particles such as clay, therefor creating a way for water and nutrients to move deeper in the soil.
My favorite product for liquid aeration is Air 8. This is a concentrate with Humic Acid as the active ingredient. I stick to the application rates on the label and mix this product in a back pack tank sprayer and spray it over the entire lawn.
Liquid aeration has a lot of benefits:
– It’s a lot easier to spray your lawn than it is to push around a core aerator.
– It’s easy to access since you can get Air 8 delivered right to your house.
– Liquid aeration is a great choice for warm season lawns that don’t want to beat up the rhizomes or stolon’s in their warm season grass that can typically occur when core aerating.
– With liquid aeration you get 100% coverage. In manual core aeration only a percentage of the lawn is being core aerated.
– Liquid aeration can be applied anytime during the growing season without the need to worry about weeds being introduced. Since there is no disturbed soil like there is in manual core aeration, you don’t have to wait until the fall (in cool season lawns) when lawn weeds are less aggressive. However, if your lawn is stressed from heat, drought, fungus, or any other reason then wait until your lawn is healthy before liquid aeration.
Overall liquid aeration is a great choice for improving clay soil for someone that doesn’t want to go through the effort of core aerating. However, if you want to really make improvements to your clay soil than I recommend core aeration combined with liquid aeration. First, core aerate, and then apply liquid aeration immediately after.
And if you want to throw everything at your clay lawn to give it the best chance for improving than I would do all of the above in the following order: Core aerate, Liquid Aerate, Top Dress, Seed and Starter Fertilizer (if you have a cool season lawn).
4. Bio Stimulants
Bio stimulants are pretty much in the same category as liquid aeration. They are liquid solutions that help loosen soil particles and promote the flow of water and nutrients.
Yard Mastery has a great selection of these solutions with information on what they specifically do. Adding a variety of bio stimulants throughout the year is just another tool at your disposal for improving clay soil. Most of these products can be applied throughout the growing season. Also, most of these are in liquid form but there is a granular option if you don’t have a back pack sprayer or just prefer application with a spreader: The Andersons 5-0-0
5. Roto Tilling
If you’re starting from scratch and don’t have a lawn yet, then now is the time to improve your clay soil! Aside from skid steers and other larger pieces of equipment, a roto tiller is your best bet for amending clay soil before seeding (or sodding). Most rental places will have roto tillers for rent. Don’t skimp out, go for one of the larger sizes.
Start out by running the rototiller over the area you are trying to plant grass. After that, spread compost over the entire area, several inches thick. Then do another pass with the roto tiller. This will work in the compost so that it mixes in with the clay soil. You can repeat this a couple of times, each time working in a couple of inches of compost.
After the compost has been mixed in, rake the area smooth, and clean up any rocks that have been churned up.
Best Grass for Clay Soil
The best grass for clay soil is Tall Fescue for cool season lawns. Tall fescue has a deep root system and is very strong. It offers strong drought tolerance, and stands up well to the heat and cold. I really like the Black Beauty Original Supreme Grass Seed Blend.
For warm season lawns Bermuda Grass is a great choice for clay soil. It’s deep rhizomes make Bermuda grass strong and resilient. Bermuda Grass is a rapid grower and has the ability to spread and fill in bare spots, as long as you keep it properly fed with a good lawn program.
Testing Lawn for Clay
You may have clay soil if you notice that fertilizers do little to nothing to green up your lawn. Assuming you’re applying fertilizers at the correct rate, you should see your lawn respond. If you’re not getting the response your looking for and your grass keeps getting weaker, it could be that clay soil is blocking nutrient absorption.
Another visual clue that you have clay soil is if you notice standing water in your lawn, or you notice bare spots that look like they’re splitting, kind of like puzzle pieces, at the surface.
Another great test is the mud shake test. It’s very simple to do at home. All you need is a small shovel and a jar. Check it out here: The Mud Shake Test.
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