Starting Grass Seed in a Former Flower Bed: Timing and Weed Control

Don’t Seed Over Live Weeds

Dormant weeds are still alive. Seeding over them guarantees competition. Eradicate first.

Best Seeding Windows for Zone 6

1. Late August / early September (ideal): Warm soil = quick germination; cool fall = strong establishment.
2. Late May / early June (second best): Slower, uneven germination; water 2–3x/week during first summer.

Dormant (winter) seeding gives poor results – avoid it.

Step‑by‑Step

1. Early spring: After weeds green up, spray glyphosate (Roundup). It only works on actively growing plants.
2. 7–10 days later: Rake out dead weeds, smooth soil.
3. Spread seed and keep seedbed constantly moist (not soggy) until germination.
4. Watering transition: From frequent light applications to deep weekly soakings once grass is up.

Weed Types and Controls

• Annual grassy (crabgrass): Pre‑emergent (e.g., Scott’s Halts) in early April.
• Broadleaf perennials (dandelion, clover): Post‑emergent on established lawn (3+ months old). Apply to moist leaves; don’t mow 24–48 hrs.
• Tough perennials (wild strawberry, violets): Spot‑treat with glyphosate; reseed afterward.

Safety

• Never apply herbicides above 85 °F.
• Avoid windy days.
• Wear protective clothing.

Eradicate weeds first, then seed in late August for the thickest, most weed‑resistant lawn.