Spring overseeding of bare patches

When it makes sense

Spring is the second-best time to sow cool-season grass. Seed comes up well once the soil warms, but the young grass has only a few months before summer heat and drought test it. If the lawn can wait, autumn overseeding is the stronger choice. If there are bare patches now, spring is better than leaving them for weeds to fill.

How to do it

1. Scarify the area first so the seed reaches soil instead of sitting on thatch and moss.
2. Loosen the surface of bare patches with a rake.
3. Sow the same seed mix as the lawn at 10–15 g/m² (about 2–3 lb per 1,000 sq ft) on thin areas; fully bare soil can take 25–35 g/m².
4. Rake lightly so the seed sits 0.5–1 cm deep, then firm it with your feet or a roller.
5. Keep the surface moist every day until the seedlings are up, usually two to three weeks.

Pick overseeding or a pre-emergent

A crabgrass pre-emergent forms a barrier in the top of the soil that stops all seed from establishing, grass seed included. If you overseed in spring, skip the pre-emergent that year and rely on a thick lawn to keep weeds out.

After sowing

Let the new grass reach about 8 cm before the first cut, and keep the mower at its higher settings through the first summer. Water deeply in dry spells; young grass has shallow roots.