Killing Grass in Daylily Beds: Selective Herbicides and Physical Barriers

Bermuda grass and other invasive grasses in daylily beds require a two-pronged approach: selective herbicide treatment followed by physical containment to prevent reinvasion.

Selective Grass Herbicides Safe for Daylilies

Products containing fluazifop-p-butyl (Fusilade, Ornamec), sethoxydim (Segment, Vantage), or clethodim (Envoy) kill grasses without harming broadleaf plants like daylilies. Key application rules:

• Apply to actively growing grass (not drought-stressed).
• Use crop oil concentrate or non-ionic surfactant per label.
• Don't mow 7 days before/after application.
• Repeat in 2–3 weeks for perennial grasses (Bermuda requires multiple treatments).
• Check label for daylily tolerance—most list ornamental lilies as tolerant.

Physical Barriers: Essential for Long-Term Control

Herbicides alone fail because grass rhizomes from surrounding lawn continually reinvade. Install deep-edging barriers:

• Metal (steel/aluminum): 4–6 inch depth, interlocking sections, virtually invisible.
• Heavy-duty plastic (polyethylene): 6–8 inch depth, flexible for curves.
• Concrete pavers (trench-set): Permanent, mow-over capability.

Install barriers after herbicide treatment kills existing grass. Extend 2–3 inches above soil to block stolons.

Integrated Management Timeline

1. Early spring: Apply selective grass herbicide as growth resumes.
2. 2 weeks later: Second application if needed.
3. Late spring: Remove dead grass; install edging barrier.
4. Ongoing: Spot-treat any breakthrough immediately; maintain 2–3 inch mulch layer.

"Grass-B-Gon" (fluazifop) is a good consumer option. For severe Bermuda infestations, professional-grade clethodim provides better systemic control. Patience is key—Bermuda eradication typically takes a full season of persistent treatment.