🌿 Overseeding Rate Calculator
Overseeding an existing lawn uses a lower seeding rate than starting a new lawn. Enter your area and overseeding rate (lbs per 1,000 sq ft) to see the seed needed.
What the tool works out
Overseeding is dosed the same way as any lawn product, per 1,000 sq ft:
lbs of seed = (area sq ft / 1000) × overseeding rateAt the defaults - 5,000 sq ft and 3 lb - that is 15.0 lb. The rate sits at roughly half a new lawn rate because the existing turf is already holding the ground; you are filling gaps, not building a stand from nothing.
| Species | Overseeding rate | For 5,000 sq ft |
|---|---|---|
| Kentucky bluegrass | 1 to 2 lb | 5 to 10 lb |
| Fine fescue | 2 to 3 lb | 10 to 15 lb |
| Perennial ryegrass | 3 to 4 lb | 15 to 20 lb |
| Tall fescue | 3 to 4 lb | 15 to 20 lb |
Seed on top of grass mostly fails
The weight of seed matters far less than whether it reaches soil. Before you spread:
- Mow shorter than usual, around 1.5 to 2 in, and bag the clippings so the seed can drop through.
- Core aerate or rake hard enough to open the surface. Seed sitting on thatch dries out and dies.
- After spreading, keep the top inch damp with short, frequent watering until germination, then water less often and more deeply.
Frequently asked questions
How much seed do I need to overseed 5,000 sq ft?
About 15 lb at the default 3 lb rate. Ryegrass or tall fescue run 15 to 20 lb; bluegrass needs as little as 5 to 10 lb because the seed is so much smaller.
When is the best time to overseed?
Late summer into early autumn for cool season lawns - warm soil, cooler air and falling weed pressure. Warm season lawns are overseeded with ryegrass for winter colour once soil temperatures drop toward the mid 60s Fahrenheit.
Should I fertilise at the same time?
A starter feed is normal, but keep nitrogen modest. Seedlings have no root system to take up a heavy dose, and the surplus washes straight off.