Removing old sod seems like a lot of work that might be unnecessary. But can you place new sod on top of the older, weedy lawn? Actually, I’ve tried this.
Laying sod over weeds creates significant problems. Weeds grow through the sod to reach the sun but also they block the sod from reaching the water and soil nutrients.
New sod requires an assertive weeding program, especially if you choose to keep the weedy sod underneath. I’ll tell you how to do it, but I don’t recommend it. It’s more of a pain in the long run than prepping the site first.
Check out Garden In Minutes' super-simple TOOL-FREE, Cypress Raised Garden Bed Kits (link to Garden In Minutes website).
How Do You Sod a Lawn With Weeds?
Here’s how you sod a lawn with weeds:
- Place sod at one end of the yard and unroll until at the opposite end of the yard.
- Place new rolls of sods right where previous sod rolls ended.
- Cut the ends that overlap at the edge of the area you want to apply it.
- Apply water on the rolls so that the lawn has only sod, soil, and water but no air pockets.
- Water every day for six weeks after placing the sod.
If you have some remaining spaces between sod applications, add some fresh soil to fill and even the area.
Laying Sod Over a Weedy Lawn
Weeds survive against all odds. Weaving through sod is no different. Not only will the weeds out-live the smothering, but they also worsen the main challenge of sodding. Sod has a critical first couple of weeks to take root and get water and nutrients.
Weeds get in the way of the rooting.
As a result, the weeds will grow strong when your lawn remains weak.
The weeds will grow at different heights with leaves of various widths, creating an uneven look. The unevenness can sometimes discolor the surface because the taller weeds will get more light, and the shorter weeds and grass will wither to a yellow or brown and struggle to survive.
Dead weeds also pose a problem. Their seeds are as aggressive as the grown plants, and the lawn is likely well-seeded even if all your weeds look dead.
These seeds will love all the TLC you give your sod, and the problem will be a vicious circle. This cycle is the reason that, when you sod, you want to remove the grass, weeds, dead clippings, and topsoil. You never know all that sleeps in the topsoil.
How To Prepare if You Must Sod on Weeds and an Existing Lawn
The time of year matters for when you choose to sod. The spring and fall seasons will provide moderate temperatures that make the work easier for you.
But they also have the periodic rainfall the sod needs.
Before you sod, you have several steps to prepare your area so that the sod has the best chance of taking root and staying healthy:
- Remove large objects: Pick up any trash, rocks, and sticks..
- Mow: If you aren’t going to remove the weeds, at least scalp them with your mower at the lowest setting.
- Level the area: Sod works best on even surfaces, so take the time to fill depressions.
- Fertilize: If your current lawn struggles, then your new sod might. Fertilizer can help.
- Water: Give the lawn a good soak a week before you sod.
If you have clay soil and want to learn the right way to do this be sure to read our complete guide on how to Improve Clay Soil for New Or Existing Lawns.
How To Remove the Weedy Lawn for Sod
If you prefer to follow the advice of removing all weeds or the existing lawn before adding sod, these tips will help. A few of these steps will sound similar to the steps with sodding over an existing sod:
- Remove large objects: Pick up any trash, rocks, and sticks.
- Weed: Kill and remove as many weeds as possible.
- Cut the sod: Use a sod cutter to remove the existing lawn. You are best off recycling the old sod rather than composting it because the weed seeds will remain viable.
- Till the area: The loosened soil 4”-12” (10.16-30.48 cm) deep will help the sod take root later.
- Water: Water the freshly loosened soil daily to complete the area’s preparation for the sod and encourage any remaining weeds to sprout.
- Wait: Give the tilled area 1-2 weeks to let any surviving weeds reveal themselves for you to kill extra thoroughly.
At this point, you would be ready to unroll the new sod.
When weeding, you will find that most weed-killing products, such as RoundUp, are based on glyphosate. Some 2,4-D weed killers such as Atrazine are good at killing broad-leafed plants but not harming common grasses.
Natural chemical weed killers can be a mixture of baking soda, vinegar, and kitchen soap. Most will have limited success in killing weeds before laying sod. More importantly, remember that when you are applying aggressive chemicals, (even natural ones), you are seriously damaging the ecosystem in the soil. Manual removal of weeds is often the best approach.
If you have a small yard, you could also do a process called solarization. You cover the area with black plastic weighed down on the edges with bricks or stones for 4-6 weeks. The plastic starves weeds of the sun’s light yet cooks them dry. This is the approach I like to take as long as I’m not dealing with a huge area.
While you do not have to till, it takes the guessing game out of your soil texture. But if you already have loose, crumbly topsoil going down 4” – 12” (10.16 – 30.48 cm), then your sod will be fine without tilling.
There are approaches to adding new sod on top of an older, weedy sod. But these approaches require more work and have less success.
Weeds have a talent for punching through the sod to get sunlight and blocking sod from getting established in the soil. If you prefer to spend less time fighting the weeds and wondering if the sod will survive, removing the old sod is more effective.