How does Bermuda grass get into flower beds?
Bermuda grass gets in three ways: runners over the soil, rhizomes under it, and seed. A barrier meets rhizomes below the soil and makes runners climb where you can see and trim them. Seed is a weeding job.
- Runners (stolons). Stems that creep over the soil. A joint that touches moist soil can root and start a new plant.
- Rhizomes. Stems that grow sideways under the soil and send up shoots. In undug soil, they usually run 1 to 6 in deep. In dug, sandy or watered soil, and along sidewalks and foundations, they can run deeper.
- Seed. Common Bermuda sets seed that can live in the soil for years and travels in lawn clippings.
What should you do before you set a barrier?
Clear the Bermuda already inside the bed. A barrier keeps new Bermuda out, but it also keeps old Bermuda in.
| Method | Use it for | What to do | Watch out for |
|---|---|---|---|
| Dig and sift | Small beds, or beds with plants to keep | Loosen the soil with a garden fork. Lift out each runner and rhizome whole. | Missed pieces can root. Plan on more than one pass. |
| Dry out and spade | Empty beds, in summer | Stop watering. Spade or till the dry soil 2 or 3 times over the summer. | Don't work moist soil. It chops Bermuda into pieces that root. |
| Black plastic | Empty beds, in summer | Mow and water, then cover it and seal the edges with soil. Leave it 6 to 8 weeks or more. | It fails in winter, when Bermuda is dormant. Any hole lets it live. |
| Clear plastic (solarizing) | Empty beds in full sun, in the hottest weeks | Mow short, water well, and cover with clear, UV-protected plastic for 4 to 6 weeks. It can kill seed too. | Shade weakens it. Afterward, don't dig deeper than 3 in. |
| Grass-only herbicide | Beds with flowers or shrubs you keep | Use a product with sethoxydim or fluazifop. Spray in spring before new growth reaches 6 in. Repeat before regrowth reaches 6 in. | Keep it away from ornamental grasses and your lawn. Check the label's list of plants it can hurt. |
How deep should a grass barrier go, and how much should show?
For Bermuda grass, set the barrier 6 in below the soil with 4 in showing. Grass Barrier landscape edging by ProTech Plastic is 10 in tall: 6 in below + 4 in above = 10 in.
The buried 6 in meets rhizomes where they usually run. The 4 in lip makes runners climb, where you can see and trim them.
| Layout | Dig the trench | Shows above the soil | Use it for |
|---|---|---|---|
| Standard | 6 in | 4 in | Bermuda and other grasses with runners |
| Low profile | 8 in | 2 in | A lower edge. Trim more often. |
| Flush | 10 in | 0 in | A hidden edge next to grass without runners. Not for Bermuda. |
The strip is 100 mil (2.5 mm) black HDPE with 200 lbf puncture resistance (ASTM D4833). It's made in the USA.
Won't shallow edging, fabric or a walk do the job?
Usually not. Edging 4 to 5 in tall, set with 1 in showing, reaches only 3 to 4 in down. Bermuda rhizomes usually run 1 to 6 in deep, as 10 in grass barrier vs shallow edging explains.
Wood-chip mulch alone won't stop Bermuda; it pushes up through. Landscape fabric helps only if the sheets overlap with no holes, and it covers the bed without edging it.
A walk, curb or fence isn't a stop either, because rhizomes can run under it. End the barrier against one only when no Bermuda grows on the far side. If lawn or a neighbor's Bermuda is beyond it, edge that side of the bed too.
How do you put in a grass barrier against Bermuda?
- Clear the bed with a method from the table above.
- Call 811 before you dig. Call a few business days ahead. The free service marks buried utility lines.
- Mark the line with a hose or rope. Edge every side that has Bermuda beyond it, even past a walk or fence. Set each end tight against the wall, walk or driveway where it stops.
- Relax the coil in the sun, so it lies flat and bends to your line.
- Dig a trench 6 in deep for the standard layout, just wide enough for a flat spade. Cut any rhizomes that cross the line, and pull the bed-side pieces out.
- Set the barrier with 4 in showing, at the same height all along.
- Join the ends with one Grass Barrier connecting kit per joint: two pre-drilled 200 mil HDPE clamps with 316 stainless hardware. Overlap the ends a little inside the clamps. It makes the joint easier to line up, and it takes no extra length.
- Backfill. Firm the soil on both sides so the edge holds its height.
- Mulch the bed. Keep mulch from building up over the top edge.
The Grass Barrier install manual has the tool list, each step and a final check list.
How much Grass Barrier do you need?
Measure every edge that needs barrier, then round up to the next 5 ft. The minimum order is 20 ft. The longest piece is 110 ft.
For a longer run, order two or more cuts, each 20 to 110 ft in 5 ft steps. Use one connecting kit per joint. A joint takes no extra length. A bed edged all the way around has a joint where the ends meet.
| Bed | Edge to cover | Order | Connecting kits |
|---|---|---|---|
| Bed against a fence, 32 × 4 ft, lawn on 3 sides, no Bermuda past the fence | 32 + 4 + 4 = 40 ft | One 40 ft cut | 0 (both ends stop at the fence) |
| Same bed, neighbor's Bermuda past the fence | 32 + 4 + 32 + 4 = 72 ft | One 75 ft cut | 1 (where the ends meet) |
| Round island bed, 10 ft across | 3.14 × 10 = 31.4 ft | One 35 ft cut | 1 (where the ends meet) |
| Border from a driveway to a fence | 150 ft | Two cuts: 75 ft + 75 ft | 1 (between the 2 cuts) |
| Small bed, lawn on one 12 ft side | 12 ft | One 20 ft cut (the minimum) | 0 |
For the border: 150 ÷ 110 = 1.4, so round up to 2 cuts. Each is 150 ÷ 2 = 75 ft.
Grass Barrier costs less per foot from 50 ft and again from 100 ft, counting every foot of Grass Barrier in the order. The border's two 75 ft cuts make 150 ft, so both get the 100 ft price. Shipping is free in the lower 48 states. See the Grass Barrier page for prices and how cut-to-length ordering works for cuts.
How do you keep Bermuda out after the barrier is in?
Trim the runners that reach the top, and pull seedlings in the bed. Do both every growing season.
- Trim at each mowing. Cut runners at the top edge with a string trimmer or shears, from spring until Bermuda browns in fall. A runner that reaches moist bed soil can root.
- Pull seedlings while they're small. Hoe or pull them, and keep a thin layer of mulch. Seed lasts years, so expect some for more than one season.
- Watch the inside edge. A shoot just inside the barrier may have come under it. Dig it out with its rhizome.
- Send clippings away from the bed. Point the mower's discharge toward the lawn. Don't mulch with Bermuda clippings unless fully composted.
Mulch takes height off the lip. For example, 2 in of mulch on the bed side leaves 4 − 2 = 2 in showing. Keep the lawn side at 4 in. After each top-up, keep mulch from building up over the top edge.
Common mistakes
- Tilling or chopping moist soil. Some of the chopped pieces root.
- Setting it flush. Runners cross the top. Leave 4 in showing for Bermuda.
- Burying the lip. Mulch or soil piled to the top lets runners bridge over.
- Leaving gaps. A gap at a walk or wall, or an unclamped joint, is a way in.
- Skipping a side. Any side with Bermuda beyond it needs barrier, even past a walk or fence.
Who doesn't need this?
- Bunch-type lawns. Tall fescue grows in bunches, so a shallow edge is usually enough. Some turf-type varieties have short rhizomes, so watch the edge the first year.
- Beds you can't clear. If Bermuda fills the bed, a barrier only fences it in.
- Bamboo. Most running-bamboo rhizomes stay in the top 12 to 18 in of soil, deeper than this strip reaches. Use Bamboo Shield, and see how deep bamboo rhizomes grow.
- Anyone who won't trim. Runners can still climb over. The barrier makes them easy to see and cut.
FAQ
Which layout should I use for Bermuda grass?
Use the standard layout: 6 in below the soil and 4 in above, after you clear the bed. The 4 in lip makes runners climb where you can see and trim them. A lower edge gives them an easier way over, and a flush edge lets them cross unseen.
Can Bermuda still get past the barrier?
It can, so plan on upkeep. Untrimmed runners climb over the top, and in sandy or deeply dug soil a rhizome can run deeper than 6 in. Dig out any shoot that comes up just inside the edge, rhizome and all, as soon as you see it.
When should I clear the bed and set the barrier?
Clear the bed in spring or summer, while Bermuda is green and growing. Plastic covers and grass herbicides don't work on Bermuda that is dormant for winter. Set the barrier as soon as the bed is clear, before new runners from the lawn reach it.