It depends on the grass. Couch needs about 10 g per m², while cool-season grasses like ryegrass and tall fescue need 25–40 g per m². They have much bigger seeds. Overseeding a thin lawn takes about half the new-lawn rate. Pick your grass type below to get the exact amount and the number of packs for your area.
Grass Seed Calculator
Grams per square metre and packs needed, by grass type
Rates are typical Australian sowing rates from seed suppliers. If your bag gives a different rate, use it (choose “Use the rate on my seed bag”). Some packs include fertiliser or coating in the weight, so their stated coverage is the one to follow.
Grass seed sowing rates in Australia
| Grass type | New lawn (g/m²) | Overseeding (g/m²) | Per 100 m² (new) | Sow when |
|---|---|---|---|---|
| Couch (hulled or blend) | 5–10 | ~5 | 0.5–1 kg | Soil 18°C+ |
| Couch (coated) | 10–15 | ~6 | 1–1.5 kg | Soil 18°C+ |
| Kikuyu (pure seed) | ~1.25 | ~0.6 | ~125 g | Soil 21°C+ |
| Kikuyu + ryegrass blend | 10+ (check bag) | ~5 | 1 kg+ | Spring or early autumn |
| Zoysia | ~10 | ~5 | 1 kg | Soil 16°C+ |
| Kentucky bluegrass | ~20 | ~10 | 2 kg | Autumn |
| Perennial ryegrass | 25–35 | ~15 | 2.5–3.5 kg | Autumn or early spring |
| Tall fescue | 25–40 | 20–35 | 2.5–4 kg | Autumn or early spring |
| Cool-season blends | 30–50 | 15–25 | 3–5 kg | Autumn or early spring |
These come from Australian seed suppliers and product packs, including Yates, Barenbrug and turf seed specialists. Kikuyu stands out because its seed is tiny and it spreads aggressively once established, so a little goes a long way. Blends are sown at a much higher rate because of the ryegrass in them, so always follow the rate on a blend’s bag.
How to work out how much seed you need
Area (m²) × sowing rate (g/m²) = grams of seed
For example, a 50 m² new couch lawn at 10 g/m² needs 500 g, which is one standard pack. The same area in tall fescue at 35 g/m² needs 1.75 kg.
Can you sow too much seed?
Yes. Sowing more than the rate doesn’t give a thicker lawn. The seedlings come up crowded, compete for water and light, and are more prone to fungal disease. Sowing too little leaves bare gaps for weeds. Stick close to the bag rate. For even coverage, split the seed in half and sow one lot walking north–south and the other walking east–west.
New lawn vs overseeding
When you overseed, you’re filling in a lawn that already has some cover, so about half the new-lawn rate is usually right. Use the full rate on bare patches. Australian turf growers don’t generally recommend oversowing warm-season home lawns with ryegrass for winter colour, because the rye competes with your main grass when spring comes. Overseeding works best with the same grass type you already have.
Can I grow buffalo from seed?
Generally, no. Popular soft-leaf buffalo varieties such as Sir Walter don’t produce viable seed, so they’re sold only as turf, runners or plugs. If you want a buffalo lawn, work out your turf with our turf calculator.
Tips for getting seed to strike
- Prepare the soil: rake to a fine, level surface over good soil. Our soil calculator helps if you need to bring some in.
- Lightly cover: rake the seed in gently or sprinkle a thin layer of top dressing. Seed should be just covered, not buried.
- Keep it moist: water lightly every day so the top centimetre never dries out. Seed usually germinates in 7–21 days, and slower in cool weather.
- First mow: wait until the new grass is around 5–8 cm tall and only take the tips off.
- No pre-emergent: don’t use pre-emergent herbicides such as Barricade for at least 6 months before sowing, or the seed won’t germinate.
Frequently asked questions
How much grass seed do I need per square metre?
About 10 g/m² for couch and zoysia, 20 g/m² for Kentucky bluegrass, and 25–40 g/m² for ryegrass, tall fescue and cool-season blends. Pure kikuyu needs only about 1.25 g/m².
How much area does 1kg of grass seed cover?
About 100 m² of couch at 10 g/m², or about 30 m² of tall fescue at 35 g/m².
How much seed do I need for overseeding?
Roughly half the new-lawn rate where about half the lawn is still covered. Use the full rate on bare patches.
Can I put too much grass seed down?
Yes. Overcrowded seedlings compete with each other and are more likely to get disease. Stick to the bag rate.
What is the best time to sow grass seed in Australia?
Late spring to summer for warm-season grasses like couch and kikuyu, once the soil is warm. Sow cool-season grasses like fescue and ryegrass in autumn, or early spring.
Can you grow buffalo grass from seed?
Not the popular soft-leaf varieties. They’re sold as turf, runners or plugs.
How often should I water new grass seed?
Lightly every day, sometimes twice in hot weather, to keep the top centimetre of soil moist until the seed germinates and establishes.
