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How to Plant Grass Seed on Hard Dirt

Planting and growing grass in hard dirt isn’t a job without its challenges, but it is completely doable with the right tools and preparation. 

Planting grass seed into hard dirt poses such a challenge as the packed soil lacks empty spaces necessary for the circulation of water, air, and nutrients, cutting off their availability to any plant life trying to grow in the tough ground. The key to seeing success when you attempt to plant grass seed in hard dirt mainly relies on the preparation of the soil, as you need to take a few extra steps to ensure it’s sufficiently broken down and aerated before you can start sowing your grass seed. 

Causes of Hard Dirt in Lawn

The first step to overcoming the challenge of growing grass in hard dirt is understanding why the soil in your lawn is hard. This can either be caused by having soil that is very clay-heavy, or soil that has become severely compacted over time, closing up essential spaces in the lawn needed for water and air to filter through it and be available to growing plants. 

Clay-Heavy Soil

Soil that is very clay-heavy is often quite naturally compacted and can become particularly hard when any moisture has dried out of it. If you live in an area with clay-heavy soil then this is likely the reason why the dirt in your lawn is hard. You can confirm this is the case by taking a sample of your soil to a local soil testing centre and having a soil test performed.

High Levels of Foot Traffic

Regular foot traffic from any people or pets who walk, run and play on your lawn will cause the soil to become compacted over time. This closes up gaps in the soil, meaning that there isn’t enough space for water and air to enrich the soil and reach any plant life growing in it.

Neglect 

Occasionally, areas of land that have been neglected for long periods of time will become hard. This is due to a lack of tilling and loosening of the soil leading to hard dirt over time.

How to Plant Grass Seed on Hard Dirt

Step 1: Test Soil

Check the condition of the soil in your lawn by having a soil analysis done. In addition to revealing the soil’s pH level and the number of nutrients it contains, soil tests can tell you the amounts of clay, sand, silt, and/or organic matters that are currently present in the soil. 

It is possible to have a soil compaction test carried out, but this is generally reserved for use on large construction sites, as opposed to residential lawns. As hard dirt in residential properties is almost always caused by either a high clay content or soil compaction, you can conduct a soil test and use the process of elimination to figure out which of the two is causing the hard dirt in your lawn. If the soil test reveals that there isn’t an issue with the soil’s composition, then compaction is most likely the cause. 

How to: Collect soil samples by using a spade or shovel to take 3-inch deep samples from 10 to 12 different parts of your lawn. Combine the different samples to make one mixture. Place 1 cup of the mixture into a soil sample box and then have it tested by your county’s Cooperative Extension Office. 

Step 2: Core Aerate Soil

Before you can sow seeds into hard dirt, you’ll need to aerate the lawn. Soil becomes compacted as a result of pockets of air being pressed out of it, which closes up the gaps that are necessary for the soil’s ability to hold air, water, and nutrients and creates a lawn full of hard dirt that won’t be able to properly support any growing plants. Aerating your lawn loosens and reintroduces air into the soil.

The easiest way to aerate your lawn is with the use of a tool called a core aerator. These tools remove small individual plugs of dirt of about 3 inches in depth, leaving small holes of air in the soil. This is an effective method of aerating residential lawns in preparation for sowing grass seed, as it breaks up compacted dirt and creates lots of empty spaces, making a more habitable environment for grassroots and improving the soil’s ability to hold onto moisture. 

You can either purchase a core aerator or rent one from a professional company. If you’re renting, a half-day rental period will be enough for average sized lawns. They’re roughly the size of a lawnmower, and have a handle and a footbar to provide extra leverage in tough soil. If you’d rather purchase an aerator that’s slightly less heavy-duty, try this lightweight Manual Core Aerating Tool.

Step 3: Till Soil

Aerating with a core aerator alone may be enough to combat the hard dirt in your lawn, but in more severe cases of compaction (particularly if the soil is very clay-heavy), the top 6 to 10 inches of the planting area will need to be tilled.

The easiest way to till soil is with the use of a machine called a rototiller. Rototillers work by digging up the top 6 to 10 inches of soil, breaking it up, and loosening it. You can easily purchase a rototiller, such this Sun Joe Electric Tiller and Cultivator. If you don’t want to purchase your own, they are available to rent by the day from professional landscaping companies. You can also attempt to aerate your lawn using a rake, but if your soil is particularly compacted this will be a difficult and lengthy task compared to using rototiller machinery. 

How to: Make sure that the soil is dry and remove any obvious debris such as large rocks in the planting area before using the rototiller. Run the rototiller across the entirety of your lawn, tilling to loosen the soil to a depth of 6 to 10 inches. 

When aerating and tilling, you’re aiming to get your soil reduced to clumps that are about the size of a pea or smaller.

Step 4: Mix Compost & Amendments Into Tilled Soil

Once the soil in the planting area has been sufficiently broken up, you should mix at least 1 to 2 inches of compost and/or soil amendments into the tilled soil. This again can be done with the use of a rototiller or rake.

The extra amendments that you add at this stage will be determined by the results of the soil analysis carried out in the first step. Based on your soil analysis, the necessary amendments could include fertilizer, which could be an organic or a starter fertilizer, as well as pH adjusting materials such as lime. The amount of these amendments you add should be equivalent to about 25% to 50% of the weight of the soil. 

How to: Using a rake or rototiller, till the compost and/or amendments into the soil to a depth of about 18 inches. Make sure the compost and amendments that you mix in weigh a total of 25% to 50% of what the soil weighs.

Step 5: Level Surface of Soil

After you have finished tilling in the necessary amendments, the surface of the lawn will then need to be leveled out and graded. To do this, you will need a flat heavy object, e.g. a length of heavy timber, and a lawn roller.

This step is essential before starting to sow your grass seed, as you need to completely remove any mounds or troughs in the planting area that will disrupt drainage and create an aesthetically unpleasing lawn when the grass starts to grow in. You will most likely need to level the land several times and should give it some time to let it settle before attempting to seed. 

How to: Take a flat heavy object, such as a length of timber. Run it over the surface of the soil back and forth several times in both directions, leveling out any mounds and filling in any troughs. Finish by rolling a wet lawn roller over the area to firm it down. Let the soil settle for at least a week before sowing any seed.

For more in-depth step-by-step guides on how to level and grade your lawn, refer to our articles How to Grade a Yard and How to Level a Yard.

Step 6: Sow Grass Seed

At this point, the planting area should be tilled, amended, and leveled, and is now ready to be sown with grass seed. You could attempt to sow the seed by hand, but this will likely result in an uneven dispersal of seeds and could grow into a patchy lawn. Instead, use a broadcast seed spreader to enable even application of the grass seed. 

Make sure that you’re sowing your new grass seed at the right time of year for the grass species that you’ve chosen. Warm-season grasses must be planted in late spring to early summer to survive, whereas cool-season grasses will do better if they’re planted in fall or winter. Different seeds and seed mixes will have different recommended broadcaster settings, so make sure you’re using the optimal settings for your seed of choice – this information can usually be found on the packaging. 

How to: Take the total amount of grass seed that you plan on using and divide it up into two equal halves. Set your broadcast spreader on the correct settings for your grass species of choice. Use the broadcaster to spread one half of the seed in one direction across the planting area, and then spread the other half across the area at a right angle to the first direction. 

Blend the seeds into the upper ¼ inch of the soil by pulling a rake through the lawn 3 to 4 times.

Step 7: Cover Planted Seeds with Topsoil

Next, add a thin layer of topsoil onto your newly planted grass seeds to prevent them from drying out or getting washed away during watering or rainfall. The topsoil that you use should be high-quality and purchased from a reputable company, and ideally should be natural and free of chemicals. 

How to: Spread a thin layer of high-quality topsoil across the planting area. Take the back of a rake and gently drag it across the area to level it out.

Step 8: Water the Newly Planted Seed

The newly planted seeds now need their first watering to trigger the germination of the grass seedlings. After this initial watering, you will need to follow a regular watering schedule that changes based on the weather conditions of your location and the stage of growth that your seedlings are at. See our guide on watering new grass seed to know the best way to continue your watering schedule. 

As a general rule of thumb, you should aim to keep the top inch of soil consistently moist throughout the early stages of germination. 

How to: Immediately after sowing, water the planting area enough so that the top 1 to 2 inches of soil are damp. 

Step 9: Apply Mulch to Planting Area

A further step you can take after watering is to add a thin layer of mulch to the surface of the soil. Mulch helps the soil to retain moisture, improves its drainage, and protects seeds from being eaten by birds and from being blown or washed away. They can also improve the structure of the soil, which in turn improves its capacity to hold nutrients. 

How to: Apply a thin layer of mulch to the surface of the soil. For best results, use aged straw or hay mulch, applying it at a rate of one square bale per 1,000 feet of soil surface. 

After Care for Grass Seed Growing in Hard Dirt

Fertilizing New Grass in Hard Dirt

If you didn’t add a starter fertilizer to the soil in preparation for sowing your grass seed, fertilize the seedlings for the first time about two to four weeks after planting. If you did add a starter fertilizer, you should instead start your regular fertilization schedule at around six to eight weeks after planting. 

Your regular fertilization schedule should involve four separate applications of a slow-release nitrogen-rich fertilizer throughout the year, roughly every eight weeks during spring, summer and fall, beginning application in the growing season. You should apply it at a rate of ½ to 1 pound of fertilizer per 1,000 square feet of lawn. Our favorite high-nitrogen fertilizer is the Maximum Green & Growth Fertilizer from Simple Lawn Solutions; it has an NPK value of 28-0-0 and is formulated to be 70% quick release and 30% slow release, meaning it will enrich your lawn with a boost of nitrogen immediately, and then it will continue to enrich it after the initial application.

Mowing New Grass in Hard Dirt

When the grass reaches about 3 inches in height, mow it using new, sharp lawn mower blades. If you have cool-season grass, cut it to about 2 inches tall, and if it’s warm-season grass, cut it to a height of around 1 to 2 inches. Continue your mowing schedule by only removing ⅓ of the grass blades’ height each time you mow.

Regular Aeration of Hard Dirt

Once or twice a year, aerate the soil using a core aerator. Do so when the soil is dry, and during the active growth periods of the grass, excluding spring. When aerating, remove the individual cores as deeply as you can, which would be to a depth of about 3 inches.

How Long Will it Take Grass Seed to Grow in Hard Dirt?

The length of time it will take for your grass seed to grow after being planted into hard dirt can be anywhere from 5 to 30 days. It mainly depends on the germination time of the grass type you chose, as this time can vary from species to species. Other factors that affect grass growth rates are the temperature of the air and soil, the level of moisture in the soil, and the amount of sunlight that the planting area sees. 

Temperature of Air and Soil

The temperature of both the air and soil have a significant effect on how long it takes for grass seed to germinate and grow. The ideal air and soil temperature for grass to grow varies depending on whether you’ve planted a cool-season grass or warm-season grass. 

Level of Moisture in Soil

Another crucial factor is maintaining the optimal level of moisture in the soil throughout the grass seeds’ entire growing process. Both overwatering and underwatering can cause problems, so you should take care to follow the proper watering schedule for each stage of the grass’ growth.

Amount of Sunlight 

Your grass will grow fast if it sees full, direct sunlight throughout the day. There’s a chance that your grass will grow in patchily if there are areas of your lawn that are in the shade at certain times during the day, but you can try to combat this problem by opting for grass species that are capable of growing in shadier conditions. 

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