How to Kill Grass for a Wildflower Meadow
Mow the grass low, cover it with cardboard or 4 to 6 mil black plastic, and leave it covered through summer. UNH Extension smothers from mid June to mid S...
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How to Kill Grass for a Wildflower Meadow
Smother it. Mow the grass as short as you can, cover it with cardboard or thick black plastic, and leave it covered all summer. UNH Extension covers turf from mid June to mid September, then pulls the cover and sows wildflower seed that fall.
This step matters most. UNH Extension says wildflower seedlings stay small and low their first year and cannot compete with lawn grass. Skipping site prep is a sure way to fail.
Plan your patch on the Pollinator Garden Desk. Pick Lawn or grass as your starting point for a step list.
Smothering Steps
- Mow as low as the mower goes, once or twice. Rake off heavy clippings.
- Do not till. Tilling brings buried weed seed to the surface.
- Lay 4 to 6 mil black plastic or an opaque tarp. Overlap sheets by about a foot.
- Bury or weigh down every edge so no light gets in.
- Cardboard works too. Wet it, pin it, and cover it with leaves or bark if you want it to look tidier. Rake the mulch off before you sow so it does not enrich the soil.
- Leave it covered through summer.
- Pull the cover in early fall. Rake off dead grass and sow in your window.
Starting Now, in Fall?
Lay the cover now and leave it on through next summer. Then sow next fall. If you want flowers sooner:
- Strip the sod. UNH Extension lists a sod cutter as an option for turf. Then sow on the bare soil.
- Sow in early spring. Pull the cover as early as you can and sow. The Xerces Society says spring sowing favors grasses over wildflowers, so cold-moist stratify the seed first.
Other Methods
| Method | Works best for | Notes |
|---|---|---|
| Black plastic or tarp | Lawn and perennial grass | No heat needed. Kills by blocking light. |
| Clear plastic (solarizing) | Hot, sunny, dry climates | Heats the soil to kill weed seed. UNH reports mixed results in the Northeast. |
| Repeated shallow hoeing | Garden beds with annual weeds | Not enough for lawn grass that spreads by roots. |
| Buckwheat or oat cover crop | Former garden ground | Residue must break down first, so sow wildflowers the next spring. |
If you use an herbicide, follow the label, and never spray when weeds are in bloom or bees are present.
Keep Soil Lean
Do not add compost, manure, or fertilizer. UNH Extension says wildflowers do best in low-fertility soil. Rich soil favors weeds and makes tall plants flop.
Related
- How to plant wildflower seeds in fall
- How much wildflower seed per square foot
- How to build a no-dig bed in fall, for vegetables instead of wildflowers
Sources: UNH Extension, Planting for Pollinators: Establishing a Wildflower Meadow from Seed; Xerces Society, Establishing Pollinator Meadows from Seed.