Overseeding Thin Areas and Eradicating Invasive Warm‑Season Grass in Massachusetts

Overseeding Thin Spots

1. Loosen bare soil with a rake or slit‑seeder.
2. Spread quality seed heavily (match existing grass color/type).
3. Firm with back of rake or roller.
4. Optional: topdress ¼ inch compost before firming.
5. Water consistently (never let top 1 inch dry) for 7–28 days until established.

The Mystery Summer Grass

The thick‑bladed grass that appears only in July–August and goes dormant in fall is almost certainly a warm‑season grass (Bermudagrass or Zoysiagrass)—unsuitable for Massachusetts. It will outcompete cool‑season grass in heat but leaves the lawn brown half the year.

Eradication and Replacement

• Best time: Early fall (after warm‑season grass is active but before cool‑season seeding).
• Method: Rent a sod cutter or use a flat spade to sever roots deeply. Remove all vegetation.
• Alternatively: Spot‑treat with glyphosate (RoundUp) in early fall; wait 10–14 days, then seed.
• Must eradicate completely before seeding cool‑season grass (ryegrass, fescue) or a persistent mix will result.

Do Not Seed Cool‑Season Grass in Mid‑Summer

Heat will kill seedlings. Wait for early fall or early spring.