Never lay sod on top of crabgrass. Crabgrass and other weeds will sprout up through the seams between your new sod and invade your lawn. Plus, sod will not be able to take root if it is laid on top of existing grass or weeds. This will result in dead sod and a rampant crabgrass infestation.
Kill all the existing weeds and grass in your lawn with a weed killer spray. Then, remove the grass, weeds, and upper layer of topsoil with a sod cutter. Throw away the grass you cut from your lawn. Then, till and level your soil. Water the bare soil for 1–2 weeks to encourage stubborn weed seeds to sprout. Spray these weed sprouts with another round of weed killer. Then, you’re ready to lay your sod.
What Happens if You Lay Sod Over Crabgrass?
Sod installed on top of existing grass or crabgrass will most likely struggle and die. One of the reasons you shouldn’t lay sod over existing grass is because a layer of grass, weeds, or thatch stops sod from sending its own roots into the soil. If your sod can’t take root, it will dry out, fail to gain nutrients, and die within weeks. All existing plants must be removed and the soil must be tilled before you can lay sod.
- Sod laid on top of any existing grass or weeds will fail to root and may die.
- If crabgrass isn’t removed, it can grow up in the gaps between sod pieces, then invade your whole yard.
- Follow our method to completely remove crabgrass before planting your sod.
Sod laid on top of crabgrass—or soil infested with crabgrass seeds—is at extreme risk of weed invasion. Stubborn crabgrass will sprout and grow up through the seams between pieces of sod. Then, the crabgrass will drop seeds onto the surface of your new lawn. Within weeks or months, your new lawn will be overtaken by invasive crabgrass.
7 Steps to Kill Crabgrass Before Laying Sod
Since you cannot lay sod on top of a crabgrass-infested yard, it’s essential to fully kill all the crabgrass first. Crabgrass can destroy your entire lawn if it isn’t properly taken care of. Here’s how to kill crabgrass so you don’t lay sod over weeds:
Spray to Kill All Plants
Before you can install your new lawn, it’s essential to get rid of weeds before laying sod. Begin by using a non-selective post-emergent herbicide to kill all the existing grass and weeds in your lawn. Roundup is a great choice. Spray all the grass and weeds with this Roundup spray, then wait 14 days for the herbicide to fully kill all the plant growth. This will fully kill the plants and stop them from growing back after you lay your new sod.
Use a Sod Cutter to Remove Grass and Topsoil
Once the crabgrass, grass, and other weeds in your lawn are dead, use a sod cutter to remove the grass. You can follow our complete guide to renting and using a sod cutter, to make this job easier. It is essential to use the sod cutter to remove the grass along with at least 3/4-inch (2 cm) of topsoil. This removes dead thatch and grass roots that can prohibit your new sod from taking root.
Till the Soil
Rent a rototiller and till the soil in your yard to a depth of 6 inches (15 cm). Tilling the soil breaks up any residual plant matter the sod cutter didn’t remove. It also loosens the soil, which encourages your sod to take root as fast as possible. If you skip this step, it’s entirely possible that your new sod will turn brown and struggle.
Roll the Soil to Level it
After tilling, use this lawn roller to level and slightly compact the soil in your yard. By properly filling your lawn roller for the right weight, you will force air pockets out of the soil, which encourages healthy sod growth. However, the soil should be loose enough that you can still poke your finger down into it. If your soil is lumpy or uneven, consider using a mixture of topsoil and compost to level your yard.
Water Your Soil
Once your lawn has been leveled, water the bare soil twice-weekly for 2 weeks. This is an essential step because tilling may have brought deep crabgrass seeds up to the surface. Watering for two weeks before you lay sod encourages these seeds to sprout, so you can kill them. If you skip this step, new crabgrass may sprout after you lay your sod, which will trigger another crabgrass invasion.
Kill New Weeds
After two weeks of watering, repeat your weed-killer spray to kill any crabgrass seedlings and other weeds or grasses that have sprouted. This will fully prepare your soil for sod and ensure that your new lawn won’t be overtaken by crabgrass. Follow the instructions on your weed killer spray. Remember, it’s essential to wait the right length of time after spraying Roundup before you lay sod.
Lay Your Sod
With your soil fully prepared and all the crabgrass removed or killed, you can begin laying your sod. Following these preparation steps ensures crabgrass won’t crop up in your yard. These steps also encourage your sod to take root fast, so your lawn won’t turn brown after installation. Before you start laying your sod, review how long it takes to lay sod. It can be a big job, so you will need some helping hands.
Can You Till Crabgrass into the Soil Before Laying Sod?
Tilling the soil before laying sod is an essential step, but it is best done after the crabgrass has been sprayed with a herbicide and removed with a sod cutter. Crabgrass that is simply tilled into the soil can resprout. This is because crabgrass is very tenacious, and can regrow from a small bit of root left in the soil.
- Do not simply till crabgrass into the soil before laying sod.
- Crabgrass should be sprayed with a herbicide to kill it—this prevents it from growing back after tilling.
- Use a sod cutter to remove a layer of soil so that your new sod lawn doesn’t cause your driveway to flood.
- Till the soil only after the crabgrass has been killed with herbicide and removed with a sod cutter.
When installing sod, it is best to remove the existing lawn (including crabgrass) with a sod cutter before you till the soil. Not only does the sod cutter remove tough plant material that makes tilling tough, but a sod cutter also removes a small layer of topsoil. This is important because sod comes with a thin layer of topsoil. If you add new sod to your lawn without removing topsoil first, the lawn will stand higher than before. This will cause water to run off the lawn and flood nearby paved surfaces, such as driveways and patios. Using a sod cutter is essential to prevent future flooding.
Can You Put Sod on Top of Crabgrass?
Laying sod on top of crabgrass is a massive mistake that can result in dead sod and a weed-infested yard. Here’s why:
- Sod cannot properly take root if it is installed over crabgrass—this causes the sod to dry out and die.
- Crabgrass can grow up through the small seams between pieces of sod.
- When crabgrass growing between sod pieces drops seeds, new crabgrass will grow on top of your sod.
- Prevent weed issues by spraying crabgrass with herbicide, then cutting out existing sod, followed by tilling and leveling the soil.
- Never lay sod on top of growing plants—this is most likely to kill your sod.
Sod laid over crabgrass dies quickly and leads to a massive crabgrass invasion in your yard. So, it’s essential to take steps to kill the crabgrass in your yard. Only after all the crabgrass is dead can you install your sod lawn.