How to Kill Grass to Create a New Garden Bed (2024)

The first step to creating any new garden bed in your lawn is to remove the existing sod. There are several methods you can take to remove the turfgrass, and each has its advantages and limitations. Which method you choose depends on the time it takes, the amount of work required, and your personal preferences.
Use the guide below to determine which method of sod removal is best for your situation.

Smothering | Heavy Mulching | Digging | Tilling | Herbicides How to Kill Grass to Create a New Garden Bed (1)

Smothering

By layering materials such as newspaper, cardboard, or plastic, you can exclude light, halting photosynthesis and causing the plants to eventually die. Smothering allows all of the organic matter to stay in place. This is one of the least labor-intensive methods for removing sod, but it is also one of the most time-consuming, often requiring the paper or plastic to be in place for six weeks or longer. Soil health can also be negatively impacted should these smothering layers remain in place after the underlying vegetation is killed. When done appropriately, this approach is one of the most eco-friendly options.

Newspaper & Cardboard

Lay 6 to 8 sheets of newspaper or 1 to 2 layers of cardboard over the area for your new garden bed. Thicker is not better, as newspaper and cardboard can inhibit water and air movement into the soil, especially if they are layered too thick. Most newspapers use organic inks, so you don't need to worry about lead contamination. Avoid the use of waxed cardboard and glossy paper, such as magazines. Remove packing tape and staples from boxes. Cover the newspaper or cardboard with an organic mulch such as compost, shredded bark, or leaf mold. This improves the appearance and prevents the paper from blowing away.

It will take several months to completely kill the plants underneath the paper so starting the process in the fall for planting in the spring is a good timeline. Ideally, the layer of paper or cardboard is removed or broken up once the underlying vegetation is completely killed so as not to obstruct water and air movement into the soil for your new garden plants. You can plant right away through the mulch-covered paper if there isn't time to wait for the grass underneath to die. Although this thick smothering layer can make it difficult to water the newly planted plants and the new plants will be in the way when it comes time to remove or break up the sheets of paper or cardboard.

Plastic

Stretch a single layer of light-excluding plastic over the area. The layer of plastic not only stops photosynthesis by blocking out the light, but it also dries out the plants by preventing moisture from getting through. Plastic has the added benefit of solarization, heating the ground and killing the grass faster. However, the extra heat can sometimes kill beneficial organisms in the soil. You will not be able to plant the area right away and will need to wait several weeks (often 6 to 8) for the grass and its roots to die before planting. Hold the plastic in place with bricks or landscape staples. The plastic can also be covered with mulch to improve its appearance, but it will need to be pulled up before planting because it is not organic.

Heavy Mulching

This method utilizes a temporary layer of mulch to smother the grass. Once killed, the excess mulch is removed from the garden area and then planted. The heavy mulching method has many of the same advantages as smothering (as it's essentially the same thing, just not using a sheet material), such as allowing all organic matter to stay in place and not disturbing the soil. Additionally, the lack of an impermeable (plastic) or nearly impermeable (newspaper and cardboard) layer eliminates many of the disadvantages seen with more typical smothering methods utilizing sheet materials.

Start by mowing grass and weeds as low as possible. Layer at least 8 inches of wood chip mulch (shredded or chipped) over the area. A depth of 12 to 18 inches is even better. The woodchip mulch will settle over one to two weeks so be sure to apply enough mulch so the final depth after settling is at least 6 to 8 inches. Keep the mulch in place for several weeks, allowing it to smother and decompose the underlying vegetation.

Pull back the mulch in a few places after 2 to 4 weeks and check on the grass. When the turf layer is dead and decomposed enough to dig through it easily, you can plant. Be sure to pull all the mulch back and plant in soil (not in the thick layer of mulch). Replace enough mulch to provide the typical 2 to 4-inch depth needed for a garden bed. The excess mulch should be removed and can be used elsewhere in the garden.

DiggingHow to Kill Grass to Create a New Garden Bed (2)

Using a spade, garden fork, or sod cutter, the existing turfgrass can be physically removed, leaving behind a weed-free garden bed to plant. Digging allows you to create a grass-free area quickly but comes with a lot of physical labor. As with smothering, this method of grass removal is eco-friendly since it utilizes no chemicals. However, digging removes a lot of organic matter and topsoil. While some of the soil can be shaken from the sod pieces, in most cases, some organic matter and soil will need to be added back to the new garden bed after the sod is removed.

Use a sharp spade to dig down and then slide the spade horizontally just under the shallow grass root system (about 1 inch down). Remove the sod in sections at a time, or roll it up as you slice underneath. The sod pieces can be re-used in other areas of the landscape. Sod pieces or rolls can be quite heavy, so be sure to keep the pieces to a manageable size. If the sod is thick, a garden fork can be used to slice underneath to leave behind more topsoil while still pulling up pieces of sod that can be easily removed.For large jobs, consider renting a sod cutter. This can significantly reduce the amount of effort and time it takes to cut out the sod.
Whether you use a spade, fork, or sod-cutter, expect to have some tired muscles at the end of the day! Remove the sod a couple of days after a soaking rain, or irrigate two or three days ahead of digging to make cutting through the soil easier. Don't work in overly wet soils - it makes the sod heavy and can lead to compaction of the soil in your new garden bed. Cover the new grass-free garden bed with mulch as soon as possible to prevent weeds from sprouting.

Tilling

Much like digging, tilling allows you to quickly create a turfgrass-free area that can be planted. Unlike digging, it allows you to retain much of the organic matter. Tilling also allows you to easily incorporate additional organic matter before planting. Most lawn areas will require a large rear-tine rototiller to break through and break up the sod. Tilling 3 or 4 days after irrigating or a good soaking rain helps reduce the amount of physical effort it takes to work the tiller through the area. Just don't till soil that is too wet. If the soil sticks to the tiller's tines or is easily formed into a ball that holds its shape, wait a day or two for the soil to dry out more.

After the soil has been turned, use a garden rake to level the soil and pull out large masses of leaves and roots. The new garden bed is ready for planting right away but would benefit from allowing the area to sit for two to four weeks to let new weeds sprout. Once the new weeds have begun to grow, lightly hoe the plants or spray them with a non-selective herbicide to kill them. Then, cover the bed with an organic mulch. This method of weed control is called the stale seedbed technique. The primary disadvantages to tilling are that it can negatively impact soil structure, brings up weed seed that easily germinates, and chops up plants and roots that can easily resprout. Utilizing a stale seedbed weed control technique allows you to reduce the number of weeds that could become established in the new garden bed.

Herbicides

Treating the area with a non-selective herbicide is a quick and easy method for killing grass that requires minimal physical exertion. The primary disadvantages to using herbicides are that there is a much higher potential to cause damage to nearby non-target plants, cause unintentional contamination to the environment, as well as cause injury to beneficial organisms or people. Read the product label carefully and be sure it is labeled for the control of grass and any other weeds or plants in the area. Take special note of the length of time the product remains active in the soil. You will not be able to replant the garden area until after the re-entry interval listed on the label. For some products, this may be as little as three days; for others, it may be three months or longer!

Always apply herbicides when winds are calm and temperatures are cool to prevent drift and damage to desirable plants. Check the forecast to insure there is no rain in the forecast within the application period denoted on the product label. Wear long sleeves, pants, gloves, eye protection, and any other protective equipment outlined on the product label. Most herbicides are only effective when applied to green leaf tissue, so be sure to apply while the grass is actively growing. When appropriately applied, most herbicides will show damage to the grass 2 to 7 days after application.Healthy turfgrass will likely require more than one application to fully kill leaves and roots. Once the grass is dead and the re-entry interval listed on the label has passed, the area is safe to plant. There is no need to dig out the dead vegetation. Plant through the dead sod and cover the area with mulch. Keeping the dead plants and root systems in place provides some organic matter and can help reduce the potential for erosion.

How to Kill Grass to Create a New Garden Bed (2024)
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