Killing Rhizomatous Grass in Flower Beds Without Harming Ornamentals

26-year battle with rhizomatous grass invading mulched beds. Past sod replacement and reseeding failed. One product worked (lost name). Current products fail. Want to kill it in beds only, not lawn.

Selective Grass Killers for Beds

• Fluazifop-p-butyl (Fusilade II, Ornamec, Grass-B-Gon): Kills true grasses (monocots). Safe over most broadleaf ornamentals. Keep off lawn grass.
• Sethoxydim (Segment, Vantage): Similar grass-selective action. Check label for ornamental tolerance.
• Clethodim (Envoy): Another grass-specific option.

Non-Selective Option (Extreme Caution)

• Glyphosate (Roundup): Kills everything green. Use shielded sprayer, wiper, or paintbrush on grass leaves only. Any contact with desirable plants = damage/death.

Application Strategy

1. Apply grass-selective herbicide when invader is actively growing (spring/early fall).
2. Repeat per label (usually 2–3 applications 2–3 weeks apart).
3. Install deep edging (metal, plastic) to block rhizome re-entry.
4. Maintain mulch depth (3–4 inches) to suppress new seedlings.

Why Lawn Control Is Different

In the lawn, the invader is the grass (or a grassy weed). Selective removal is nearly impossible. In beds, you're killing grass among broadleaf plants—easy with the right tool.