Winning the War on Invasive Grass in Herb Gardens

Identify the Enemy: Bermuda Grass vs. Clump Grasses

In hot, low-desert gardens, creeping grasses can smother herbs within weeks. If it's Bermuda grass (spreading by underground rhizomes), surface mulch or barriers won't work—it grows sideways beneath them. The only permanent solution: thorough fall digging to remove every rhizome fragment. Even Roundup misses pieces.

After Eradication: Mulch Deep, Renew Yearly

Once cleared, apply 4+ inches of shredded bark mulch. This suppresses new weeds, conserves moisture, and builds soil. Replenish annually. For non-rhizomatous grasses, heavy mulch alone may suffice if applied before seeds germinate.

Prevention Strategies

• Install deep edging (12+ inches) around beds to block rhizome invasion.
• Use landscape fabric only after complete rhizome removal, topped with thick mulch.
• Monitor edges monthly; pull runners immediately.
• Consider raised beds with hardware cloth bottoms for total exclusion.

One thorough digging session in autumn eliminates the problem for years. The effort pays off in cleaner beds and healthier herbs.