To prevent grass from invading your garden, use a garden border that goes deep enough to stop spreading grass roots and is high enough that grass runners can’t crawl over it. Additionally, spread mulch to suppress grass growth, mow in a pattern that keeps grass clippings out of your garden, prevent grass seed from entering your garden, and use herbicidal measures to stop invasive grass.
7 Methods to Prevent Grass from Growing Over Edging
Try the methods below to keep grass out of a garden or growing over edging
Choose the Right Garden Border
To serve as an effective border, whatever you place along the edge of your garden should have at least two of the following three qualities: depth, width, and height. A shallow border allows grass to send spreading rhizomes (roots) into your flower bed. A short or narrow border lets creeping stolons (runners) jump the fence into your garden.
- The foot of your garden border should extend 2 inches (5 cm) below the soil surface to stop spreading grass roots.
- Choose a border that is either at least 4 inches (10 cm) wide or 3 inches (5 cm) tall to stop grass runners from crossing over it.
- Use a solid border with no gaps where grass can invade.
- This garden border is ideal for keeping grass out.
In addition to specially designed garden borders, fieldstones, rocks, bricks, and pavers make attractive borders. Railroad ties are also very effective at stopping spreading grass. Short borders, or wire borders with openings, will not stop grass.
Dig a Trench
A 3–5 inch (7.5–13 cm) wide trench is effective at keeping grass out of gardens and off of paved surfaces such as driveways and walkways. The trench should be 4 inches (10 cm) deep to stop invasive grass roots.
- Dig a 3–5 inch (7.5–13 cm) wide trench along the border of your garden or paved area.
- The ideal trench depth is 4 inches (10 cm).
- Maintain the trench with regular edging.
The key to a functional trench is to keep it clearly defined and grass-free. Make sure grass roots and runners do not attempt to cross the trench into your garden.
Spread a 4-inch deep (13 cm) layer of mulch in your garden. This layer not only suppresses weeds, but also keeps grass from growing in your garden. Grass plants sprouting from below will struggle to reach the sun and die. Meanwhile, any grass that spreads via runner won’t be able to take root in mulch.
Keep Grass Clippings Out
Grass clippings can carry seeds or bits of root. If they are allowed to enter your garden, they can “jump” over your edging and take root quickly. To prevent this, mow in a pattern that casts grass clippings toward the center of your lawn, away from the soil where you do not wish grass to root. When edging your yard, hold the string trimmer or weed eater so that the plastic guard blocks grass from entering your garden.
Seed Grass Carefully
When you overseed your lawn, make sure to follow a pattern that prevents the seed spreader from throwing grass seeds into your garden. If this is impossible to do, consider making a temporary barrier from cardboard or plywood. This barrier can deflect flung seed and keep it on your lawn, out of your garden.
Edge Your Lawn Regularly
The best defense against grass that crawls over edging is preventative maintenance. Edge your yard every time you mow. Additionally, edge deeply to keep borders and trenches defined. By cutting the grass down to the soil level, you cut sneaky runners and roots that attempt to invade areas where they don’t belong.
A post-emergent herbicide spray like Roundup will attack and kill grass, but it won’t poison the soil. Roundup only attacks plants it is sprayed on. As long as you use it to target only grass, it poses no threat to garden flowers and vegetables.
- Spray invasive grass with this Roundup product designed for use near gardens.
- Apply this pre-emergent herbicide to your garden in spring, to stop seeds from sprouting.
If you want to stop grass seeds from sprouting in your garden or other areas, use a pre-emergent herbicide in spring and fall. Pre-emergent herbicide kills seeds as they attempt to sprout, but won’t harm mature plants. You can spread pre-emergent in your garden and as long as you aren’t planning to seed in the next 3 months, the plants there will be safe. Be sure not to apply pre-emergents and post-emergents at the same time.
How to Stop Grass Growing Over Your Garden Edging
To halt grass as it tries to leap over your garden border and invade spaces meant for other plants, use the following methods:
- Install a solid garden border that extends 2 inches underground and 3 inches aboveground.
- Dig a 3-inch wide, 4-inch deep trench along the edge of your garden or paved area.
- Spread a 4-inch deep layer of mulch in your garden.
- Mow in a pattern that blows grass clippings away from garden areas.
- When spreading grass seed, use temporary barriers to keep seed out of your garden.
- Edge your lawn regularly, making sure to cut all invasive grass runners and shallow roots.
- Apply a post-emergent herbicide to kill invading grass.
- Use a pre-emergent herbicide to stop grass seeds from sprouting in your garden.
You can use one or all of these methods together to grass-proof your garden. This will contribute to a healthy, hassle-free yard with a pristine appearance.