It’s a ton of work to remove grass before you build a raised bed, but is it even necessary? After all, the weight of soil will probably cause the grass to die out over time – right? Maybe…
So, can you put a raised garden bed on grass? You can put a raised garden bed on grass – but you should take steps to stop grass from growing up into the raised bed. One way is to smother the grass with cardboard or plastic, and then pile up the soil in your raised bed to a depth of at least 12 inches (30 centimeters).
Another option is to remove the grass before building your raised garden bed. This will prevent the grass from growing up into the raised bed.
Let’s take a closer look at how to remove grass before planting a raised bed. We’ll also look at ways you can build your raised garden bed on grass, some of which do not require chemicals, digging, or heavy equipment.
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Can You Put A Raised Garden Bed On Grass?
You can put a raised garden bed on grass. If the soil is piled deep enough, it will smother the grass underneath.
But, if the soil is too shallow, it won’t kill the grass below. In that case, the grass will grow up through the soil and compete with your plants for water and nutrients.
(The Utah State University Extension suggests killing the grass before building a raised bed).
There are two basic options for building a raised bed where grass is growing:
- Remove the grass before building your raised bed
- Kill the grass in place before building your raised bed
Let’s start off with some ways you can remove the grass before building a raised garden bed.
How To Remove Grass For A Raised Garden Bed
Removing the grass before you build a raised garden bed is a lot of work, whether you do it with a shovel or power equipment. However, removing the grass ensures that you won’t have any grass growing up into your raised garden bed once it is built.
Just remember to call the utilities in your area to check for underground lines (gas, water, etc.) before you do any digging. This advice applies even if you think the digging will be shallow!
Dig Out The Grass
One of the simplest ways to remove grass is to just dig it out. At a minimum, you will need a shovel, 4 stakes, and some rope or twine for this job. A pitchfork and wheelbarrow will also be helpful.
First, mark off the area where you want to remove the grass. This area will need to be at least as large as the raised bed itself.
To mark off the area, drive a stake into the ground at each of the four corners of the spot you want to clear. Then, tie a rope or string between the stakes to mark the edges.
These ropes will guide your digging and prevent uneven edges. Use the shovel to dig as deep as the roots go, and pull up manageable chunks of grass as you go.
You will need to do this for the entire area you marked off. I know, it’s a lot for a big area. Take my advice: for a large bed, do this project over multiple days, especially if you are not used to digging!
Otherwise, you will be sore (very much so). Once the digging is done, you can use the pitchfork to remove soil from the roots of the grass.
Put the soil back where it was. That way, you won’t need as much material to fill the area back in.
Toss the grass and roots into your wheelbarrow and move them to your compost pile. Leave the chunks of grass on top of the compost pile, with the roots facing up. That way, the grass cannot establish itself on your compost pile.
Use as much extra soil as necessary to fill in the area you dug up. Use a rake to make it level with the surrounding ground. Now you are ready to build your raised bed!
Use Power Equipment
If you want to get rid of grass without digging, then power equipment is an option. A turf cutter or tiller can help you remove grass to prepare for a raised garden bed.
Sod Cutter (Turf Cutter)
You can either buy or rent a sod cutter (turf cutter) to help remove grass. A sod cutter is a machine that removes a strip of grass with the roots and soil still attached.
The best part about using a sod cutter is that you can reuse the grass after you remove it. After cutting out a strip of sod (grass, roots, and soil), you can move the strip somewhere else in the yard where you want grass to grow.
(You can also offer the sod strips to anyone who has bare spots on the lawn that need to be regrown).
If this method sounds good, you can rent a sod cutter at many Home Depot locations.
Tiller (Rototiller)
A tiller (or rototiller) is another piece of power equipment you can use to remove grass. There are both electric and gas powered tillers.
Remember that a tiller will tear up the grass and separate it from the roots. As a result, you will not be able to replant the grass elsewhere in the yard.
If you just want to compost the grass, a tiller is a good option to save yourself the work of digging. A rototiller is helpful if you need to break new ground when starting a garden for the first time.
(You can learn more about rototillers in my article here.)
After you use the tiller to tear up the grass and break up the ground, you can put the grass in your compost pile (roots up!) That way, you can reuse the organic material and nutrients for next year’s garden.
You can rent small or large rototillers at Home Depot. I go into more detail about the weight of rototillers in this article.
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How To Kill Grass (Without Chemicals)
If you would rather kill the grass before building your raised garden bed, you do have some options. The methods I have listed below will kill the grass without any digging, chemicals, or heavy equipment.
Organic Weed Killer
If you do not want to use herbicides to kill grass in your garden, I don’t blame you. There are some nasty chemicals in those products, and they can kill the plants you do want to grow (like the vegetables or flowers in your raised bed!)
Luckily, there are some organic weed killers you can use to avoid harsh chemicals. The Utah State University Extension has many home remedies for weed and grass control listed in this article.
One method they mention is to apply a solution of salt water to the grass. The upside is that this salty solution will kill the grass. The downside is that other plants nearby (or ones in your raised garden bed) might not like the salty soil either!
You can also try spraying the grass with a solution of vinegar. The acidity might kill the grass, but it could also hurt nearby plants, so be careful when using this method.
Another method is to use boiling water to kill the grass. Just be very careful when moving boiling water from the kitchen to the garden.
Remember that if you splash boiling water on nearby plants, it will kill them too. Boiling water does not discriminate!
Cover With Plastic (Solarization)
If you have some time to spare, you can use a combination of solar energy and the greenhouse effect to kill grass. This method requires some time and patience, but it doesn’t take much work on your part!
First, use a plastic sheet to cover the area where you want to kill the grass. A dark plastic tarp will work. However, clear plastic will work better, according to the Cooperative Extension.
Use stones or bricks to weigh down the corners and edges of the plastic. This keeps the plastic from blowing away or moving out of place in the wind.
After the plastic is securely in place, leave it for 4 to 8 weeks. The sun will heat up the air and soil underneath the plastic.
The plastic will keep the heat from escaping (using the greenhouse effect to your advantage!). The sun will continue to heat up the air and soil under the plastic over time. Eventually, the grass will die from the heat.
Note: the soil needs to be covered during the warm part of the season. Otherwise, the soil will not heat up enough, and the grass will not die.
This method will take a couple of months, and the sun needs to be strong. If it is already spring and you need to kill the grass this year, look into another method.
Smother With Cardboard Or Newspaper
First, cut the grass as short as you can. To do this, adjust your mower so that the blades are as low as possible. Watch out for rocks while you are mowing with the blade set low!
Then, cover the grass you want to kill with a thick layer of cardboard or newspaper. A thicker layer is more likely to kill the grass and keep it from growing back. However, a thick layer will also take longer to decompose.
After this layer of cardboard or newspaper is in place, build your raised garden bed over it. When the cardboard or newspaper decomposes, along with the grass, it will add nutrients and organic material to the soil.
Use A Raised Garden Bed Liner
If you use the right liner, you might be able to prevent grass from growing up into your raised garden bed.
A liner made of plastic or landscape fabric will prevent grass from growing up into your raised garden bed. However, there are some downsides to using raised garden bed liners.
For example, plastic raised bed liners will reduce drainage. You can learn more about how to improve drainage in your raised garden bed in my article here.
You will have to weigh the pros and cons of liners for your specific situation. You can learn more about the pros and cons of raised garden bed liners, along with what materials are available, in my article here.
Pile Up The Soil High
Finally, if you pile up the soil high enough in your raised garden bed, you will not have to worry about grass growing up through it.
If the soil is piled up to a height of 12 inches (30 centimeters) or more, then grass does not have much chance of breaking through.
Conclusion
Now you know what to look out for if you decide to build a raised garden bed on grass. You also have some ideas about how to kill or remove the grass before building your raised garden bed.
If you need to figure out the volume of your raised bed, try our soil volume calculator here!
You can learn about how to grow grass under trees here.
I hope you found this article helpful – if so, please share it with someone who will find the information useful.
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~Jonathon
You can put a raised garden bed on grass – but you should take steps to stop grass from growing up into the raised bed. One way is to smother the grass with cardboard or plastic, and then pile up the soil in your raised bed to a depth of at least 12 inches (30 centimeters).