How to Keep Grass Out of Your Garden [6 Grass-Proof Steps]

To prevent grass from invading your garden, begin by laying landscape fabric in your garden. You can cut slits in the fabric where your plants are growing, so none of them will be killed in the process. Next, spread 3–5 inches (8–13 cm) of mulch on top of the fabric. Follow up by digging a trench to separate your garden from the lawn. Then, install a border to prevent grass from spreading into your garden. Finally, if you want to prevent grass seeds from sprouting in your garden, spread pre-emergent herbicide in your garden in spring.

How to keep grass out of garden

6 Steps to Make Your Garden a No-Grass Zone

Grass spreading into garden beds can destroy the look of your garden. Plus, the grass can choke out your garden plants by stealing essential water and soil nutrients. In order to make sure grass does not invade your garden, follow these steps.

Add Landscape Fabric

Stop grass in its tracks by laying landscape fabric throughout your garden. Water-permeable landscape fabric allows moisture to reach the soil and feed your plants, but it stops grass seeds from sprouting up through the fabric. You can even lay landscape fabric in a garden without harming your plants.

A layer of landscape fabric held down with lawn staples on a garden bed to prevent grass and weeds from growing.
I installed a layer of landscape fabric on this new garden bed to prevent grass and weeds from growing.

Here’s how to install landscape fabric to keep grass and weeds out of your garden beds:

  • Rake any mulch, leaves, or other ground covering out of your garden.
  • Use this water-permeable landscape fabric to create an anti-weed barrier on top of the soil.
  • When laying landscape fabric on the soil where garden plants are already growing, cut an ‘X’ in the fabric where each plant is growing. Then, fold back the flaps so the plant can pass through the fabric.
  • When laying sheets of landscape fabric side-by-side, overlap them by 6 inches (15 cm).
  • Secure landscape fabric to the ground with landscape staples.
  • Drive a landscape staple through the fabric every 12 inches (30 cm) along the edges of your garden and where sheets of landscape fabric overlap.
  • Fold or cut landscape fabric so that it follows the edge of your garden.
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These landscape staples can be pushed into the ground with your hand or using a rubber mallet.

A box of 500 Vigoro fabric and garden staples laying in a garden bed of mulch.
I use these simple fabric and garden staples to install landscape fabric in my gardens.

Use these steps to cover all of the ground in your garden beds. Everywhere that the fabric covers, weed and grass seeds will be unable to sprout. Grass can’t grow through the fabric. If you need to add new plants in the future, just cut an ‘X ‘in the fabric and fold back the flaps so you can plant directly in the soil.

Create a Thick Mulch Barrier

To keep grass at bay, maintain soil moisture, and provide a finished look to your garden, add a 3–5 inch deep (8–13 cm) layer of mulch on top of the landscape fabric. You can use any mulch you like. Bark mulch, wood chips, nut hulls, shredded leaves, and gravel are all good choices. However, it is best to avoid straw, hay, or grass clippings. These can carry grass seeds that sprout in your garden.

  • Spread mulch on top of your landscape fabric until it is 3–5 inches (8–13 cm) deep.
  • Make sure the entire garden is covered evenly.
  • You can use organic mulch or stones, depending on your preference.
  • Do not use grass clippings or straw mulch, since they can introduce grass seeds to your garden.

A thick layer of mulch prevents grass seeds and runners from entering your garden and taking root in the soil. Plus, any grass seeds that sprout will be smothered by the thick mulch.

Dig a Trench

If your grass is prone to spreading from your lawn into your garden, it’s best to dig a small trench that separates the two. Use a round-nosed spade shovel to dig a trench 4–6 inches wide (10–15 cm) along the edge of your garden.

  • Dig a trench along the edge of your garden to separate the lawn and garden spaces.
  • The trench should be 4–6 inches wide (10–15 cm) and 2–3 inches deep (5–8 cm).
  • Trenches are extremely effective at preventing runner-producing grasses from spreading into gardens.

The ditch does not need to be extremely deep. A depth of 2–3 inches (5–8 cm) is sufficient. This will prevent runners from jumping the gap and getting a foothold in your garden. In addition to creating a barrier against grass, digging a trench also makes the next step in the process far easier.

Install a Border

Garden borders are one of the best ways to prevent grass from growing over edging. A garden border is a low barrier of metal, wood, stone, or plastic that separates the lawn and garden. Not only will a border stop grass runners, but it also prevents grass seeds from taking root at the edge of your garden and infiltrating your desirable plants. To install one:

  • Choose a garden border, such as this aluminum garden edging.
  • Instead of processed materials, you can make your own garden border from rocks or wood.
  • Install the border along the edge of your garden, with the trench between the border and your grass.
  • For best results, make sure there are few or no gaps in your border, to keep grass out.

Borders not only keep unwanted grass out, but they also keep important materials in your garden. With a garden border in place, your mulch is less likely to spread out and become mixed with soil. This maintains a thick mulch barrier that keeps grass and weed seeds from sprouting in your flower beds.

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Use Special Lawn Care Tactics

A regular lawn care schedule will help prevent grass from growing in your garden beds. Begin by edging your lawn every time you mow. Make sure to edge the grass along the trench and garden border, to keep it a few inches from the garden. This will help prevent invasive grass.

  • Use a string trimmer to cut the grass along the garden border every time you mow.
  • Mow your grass before it begins producing seeds.
  • When mowing, discharge grass to the inside of the yard, away from garden beds.
  • Use a bagger attachment to collect grass clippings, if desired.

In addition to edging, mowing is essential for a grass-free garden. Mow your grass before it grows tall enough to produce seed heads. When you mow, make sure you do not discharge any grass clippings (which may contain seeds) into your garden. Mow so that the grass is discharged toward the inside of your lawn or mow with a bagger attachment. Bagging grass clippings is a great way to keep dead grass and living grass seeds out of your garden.

Apply Pre-Emergent Herbicide

If you want to absolutely stop grass seed from sprouting in your garden, spread a pre-emergent herbicide in spring. Pre-emergent is a specific type of herbicide that only attacks seeds as they attempt to sprout. It does not kill mature plants, so you can spread it in your garden without harming your plants. It will kill all grass seed that attempts to sprout for months after application.

  • Spread this garden-friendly pre-emergent herbicide in your garden to kill grass and weed seeds as they sprout.
  • Pre-emergent herbicides won’t kill mature plants.
  • Pre-emergent herbicide kills all seeds as they germinate in the soil, so it should only be used if you are not growing plants from seed.
A container of Preen pre-emergent weed preventer laying in a green grass lawn.
I use Preen early in the season to prevent future weed and grass growth into my garden beds.

It is essential to keep in mind that pre-emergent herbicide is a non-selective herbicide. This means it will kill all seeds as they germinate, including the seeds of flowers and vegetable plants. So, you should only use it if you are not attempting to grow any desirable plants from seed in the next few months.

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How Do You Stop Grass from Growing in Your Raised Beds?

Mulch is the best defense against grass growing in raised beds. In almost all cases, grass sprouting in a raised bed comes from seeds carried into the bed by the wind. If you have a 3–5 inch (8–13 cm) layer of mulch in the raised bed, the grass seeds will struggle to sprout. Even if they find their way down to the soil, they will be smothered by the mulch before they grow tall enough to reach the sun.

  • Add 3–5 inches (8–13 cm) of mulch on top of your raised bed soil to smother grass seeds.
  • If grass continues to sprout through the mulch, remove the mulch, cover the soil in water-permeable landscape fabric, and then add mulch on top of the fabric.

You can add a layer of landscape fabric on top of your raised bed soil, followed by mulch, if you want extra protection from unwanted grass. However, in most cases, mulch is sufficient. Just make sure to add mulch every 6–12 months, to replace mulch that has decomposed or been displaced.

How Do You Keep Grass Out of Your Garden?

If grass is growing in your garden, keep it out with these tips:

  • Lay water-permeable landscape fabric on top of the soil.
  • Add a 3–5 inch deep (8–13 cm) layer of mulch on top of the fabric.
  • Dig a 4–6 inch wide (10–15 cm) trench separating your lawn and garden.
  • Install a garden border made of wood, plastic, stone, or metal edging.
  • Mow and edge your lawn regularly to keep grass from encroaching on your garden.
  • Apply a pre-emergent herbicide to your garden in spring to kill grass seeds that try to sprout.

With these tactics, you’ll prevent grass seeds, roots, and runners. So, your garden will remain a haven for your plants.

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