How to Reseed a Lawn — Complete Renovation Guide

Whether you're overseeding thin patches or starting a full lawn renovation, the same fundamentals apply: right timing, good seed-to-soil contact, and consistent moisture. This guide covers every step from soil prep to the first mow.

Overseeding vs full renovation — which do you need?

Lawn condition	Recommended approach
70%+ healthy grass	Overseed thin areas
50–70% healthy	Full overseed after aeration
Less than 50% healthy	Full renovation (till + reseed)
Mostly weeds	Full renovation with herbicide first

Material calculator

Grass seed

Grass type	Overseeding rate	New lawn rate
Tall fescue	3–4 lbs / 1,000 sq ft	6–8 lbs
Kentucky bluegrass	1–1.5 lbs	2–3 lbs
Perennial ryegrass	3–4 lbs	6–8 lbs
Bermudagrass	0.5–1 lb	1–2 lbs

Topsoil (for bare areas)

Area (sq ft) × Depth (in) ÷ 324 = cubic yards

For 1,000 sq ft at 1 in: 1,000 × 1 ÷ 324 = 3.1 cu yd

Starter fertilizer

1 bag (typically 5,000–7,500 sq ft coverage) per application area.

Full lawn renovation — step by step

Week 1 — Kill existing vegetation

Apply a non-selective herbicide (glyphosate) if the lawn is more than 50% weeds. Wait 7–14 days for vegetation to die and dry out before tilling.

Week 2 — Till and grade

Till 4–6 inches deep. Break up clumps. Rake level, sloping away from the house at 1–2% grade. Add 1–2 inches of topsoil or compost and till in if soil is poor.

Week 3 — Seed and fertilize

Apply starter fertilizer and rake into top 1 inch of soil
Spread seed with a broadcast spreader in two passes (half north-south, half east-west)
Rake lightly to ensure seed-to-soil contact
Roll with a water-filled lawn roller to press seed into soil

Weeks 3–5 — Keep moist

Water 2–3 times daily to keep the top 1 inch of soil continuously moist until germination. Never let the seedbed dry out — this kills germinating seeds. Once seedlings are 1 inch tall, reduce to once daily.

Week 6–8 — First mow

Mow when grass reaches 3–4 inches tall. Set mower to 2.5–3 inches. Never remove more than 1/3 of blade height at once.

Overseeding an existing lawn

Mow existing lawn short (1.5–2 inches)
Dethatch if thatch layer exceeds 1/2 inch
Core aerate (2–3 passes)
Apply starter fertilizer
Broadcast seed at overseeding rate
Water daily until germination
Resume normal mowing schedule at 4 weeks

Post-seeding calendar

Week	Task
1–2	Water 2–3×/day; no foot traffic
3	Germination visible; reduce to 1×/day
4–5	First fertilizer application (if not pre-applied)
6–8	First mow at 3 in height
12	Full normal lawn care resumes

Frequently Asked Questions

When is the best time to reseed a lawn?

Early fall (August–October) is the best time for cool-season grasses (fescue, bluegrass, rye) — soil is warm but air is cooling, reducing weed competition. Spring is the second-best option. For warm-season grasses (bermuda, zoysia), seed in late spring when soil temps exceed 65°F.

How much topsoil do I need before reseeding?

For bare areas, add 1–2 inches of topsoil and rake level before seeding. For overseeding existing thin turf, no topsoil is needed. For a full lawn renovation (50%+ dead), till 2–4 inches of topsoil or compost into the top 4–6 inches of soil.

Should I aerate before reseeding?

Yes. Core aeration before overseeding dramatically improves germination rates — the seed falls into the holes and makes direct contact with soil. Rent a core aerator for $80–$150/day. Skip the spike aerator (it compacts soil rather than relieving it).

How long does it take to grow a lawn from seed?

Germination takes 7–21 days depending on grass type and soil temperature. An established, mowable lawn takes 6–10 weeks from seeding. Full density and durability takes one full growing season (spring to fall).

Do I need to cover grass seed with topsoil?

No — grass seed needs light to germinate and should not be buried deeper than 1/4 inch. After seeding, lightly rake to make seed-to-soil contact. You can apply a thin layer (1/4 in) of peat moss or straw to retain moisture without burying the seed.

How to Reseed a Lawn — Complete Project Guide