How to get grass to grow in clay soil

Tudor Sebi

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Grass is known to be quite a hardy component in a garden to grow in most soil types. However, hard clay soil could prove to be a challenge for grass which is the reason homeowners and gardeners are frustrated when it is difficult to turn a plot of clay soil into beautiful greens.

Most homeowners want green turf as the grass is soft and ideal for covering the ground for aesthetics and functionality. It should be soft enough to sit on or walk barefoot yet strong enough to handle heavy traffic. But soft lush greens do not grow well in soil mixed with a high percentage of clay. But there are ways to overcome a hard patch of clay soil to become conducive for a grassy yard.

Clay Properties

Clay soil possesses several good qualities although it may seem an unfavorable candidate for grass. Clay has extraordinary moisture retention besides better levels of nutrient content compared to other types of soil.

It does take more effort in breaking up hardened clay to prepare it for laying sod. A simple solution would be to add organic matter to make the clay more permeable with better drainage to encourage a lush, green lawn. To secure workable clay soil, the gardener must be prepared for a long-term process to ensure the best ground conditions for a great lawn outcome.

Gardeners need to prepare early by prepping the clay; that is, about a year before putting on the sod. Good cultural practices must be exercised to get the clay soil in the right condition. This includes adding organic matter twice a year to maintain the right conditions for green turf growth.

Step 1 – Test the pH of the soil

The prepping process of clay soil is to test its pH value. Most grasses grow best in slightly acidic soil; that is a pH value between 6 and 7. Soil with a pH below 6 is too acidic for good growth; lime must be added to raise the pH value before grass can be planted. The scientific name for lime is calcium carbonate which could be found as ground limestone, pelletized limestone, or dolomite limestone.

But if the soil has a pH above 7, it is too alkaline; it must increase in its acidity level using sawdust and peat. The length of time in prepping clay soil depends on the amount of clay in the soil to grow a lush, healthy lawn which may take at least 2 years. Experienced gardeners would be mindful to determine the ground density for their preferred or selected grass type.

Step 2 – Break up Hard Clay Deposits

Once the pH of the clay is adjusted, the hard clay deposits must be broken up as the big clay blocks hinder grass growth as grass roots are short and weak, unlike most weed roots. It helps if the soil is tilled to aerate the ground. Hence, turf grass grows well when the soil is less compact.

The best type of soil from prepped clay could be tested by scooping ½ cup of soil into the palm with a few drops of water to knead the soil into a ball. If the ball could be easily pressed with the thumb and index finger to form a flat ribbon, it should spread out into 1-2 inches long for a well-formed clay-loam composition. A heavier clay soil would form a longer ribbon which is inappropriate for grass turf growth.

Step 3 – Add Topsoil and Other Components

Once the ground soil is ready, add topsoil, grass seed, and other organic matter to the top layer of the tilled clay soil. Mulch, compost, gypsum, and manure could be added to provide the necessary nutrients that grass thrives on. Gypsum is good at breaking up the soil particles to promote better aeration to the top layer.

Spreading such organic compost on the clay soil surface area of about 6 inches deep is great in preparing the ground with well-formed clay-loam soil to encourage green grass growth. If heavier clay soil persists even with prepping, the organic compost should be deepened to 8 inches instead.

The rich compost must be worked diligently into the soil with a tiller for breaking clumps to enhance organic matter dispersion. The soil must be left to rest for at least 2 months. The soil should be tested again using the ball test to confirm the right proportions of organic matter for good growth.

If the clay soil is still too heavy or dense, spread in another layer of organic compost and wait another period before executing the ball test until the right clay soil structure is achieved. Time is needed for the compost to change the soil composition.

Step 4 – Choice of Grasses

Since there is no better choice of soil than clay, choose grass types that grow well in it. Bermuda grass is a hardy warm season grass while bluegrass is known to be a cool-season grass. Both types tolerate clay soil quite satisfactorily.

The lawn area must be properly measured for the amount of grass seeds or plugs required according to the manufacturer’s recommendation for the selected grass type and space.

The selected seeds should be divided into 2 applications for seeding with half over the area using a broadcast spreader in a vertical path and the other half in a perpendicular direction for even coverage. The seeded area should be rolled over with a lawn roller full of water before spreading the top with a thin layer of straw mulch.

Gardeners could also scatter grass clippings across the lawn to promote growth in the clay soil. However, a check must be kept on the amount of grass clippings to avoid developing a thatch problem.

Step 5 – Mix grass seed with clover seed

Grass plugs could be planted in holes 6 inches apart along the lawn area. Water must be sprinkled on the soil to moisten the holes with one plug in one hole. Again, roll the planted area with a lawn roller filled with half a tank of water.

Besides the best choice of grass type, good grass growth could be encouraged with clover seed as the latter has long roots to break up the chunky clay. Clover seed also contributes nitrogen to the soil for better soil condition.

Clover is also a great grass alternative for soil amid an extremely high clay percentage. Its advantage is its short growth which does not require frequent mowing. However, it does not handle traffic well. Moreover, clover attracts bees easily.

Step 6 – Avoid overwatering

The lawn cannot have too much water as it would compact the clay even more to become hard. The grass would also “drown” with too much water and no proper aeration.

The planted area must be moistened with only ¼ inch of water. This is best executed with a sprinkler where water is applied 1-2 times a day to ensure evenly moist soil without oversaturation until the grass comes out.

A small water can is also useful in ensuring the limited amount of water to be applied at this point.

Final Outcome

Grass in clay soil needs time to grow even if the clay soil has been prepped. It could be months or seasons for the prepped clay soil to become conductive for the grass to grow favorably.

A lot of hard work must be put in to change the clay ground composition from heavy soil to light soil with sufficient nutrients. This is where diligence is required in adding proper components of organic materials into the clay soil before laying the sod is ideal to get grass turf going.

Tips for better growth

There are certain tips in which grass would grow better in clay soil.

1) A variety of cool-season grasses should be planted during the fall or spring. These grass varieties help to work out the clay-loam soil throughout the year. Gardeners could choose from annual ryegrass, hard and red fescue, colonial bentgrass, Kentucky bluegrass, and perennial ryegrass.

2) A variety of warm-season grasses like plugs could be planted from late spring to early summer. These varieties are great for working out clay-loam soil. Gardeners could choose from Bermuda grass and buffalo grass to Zoysia and Saint Augustine grass.

3) Always test the pH and nutrient levels of the clay soil way ahead of laying new sod to enjoy the best outcome.


Tudor Sebi

A 20-year lawn mower expert, offering insightful guidance for optimal maintenance and top-notch landscaping solutions

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