How deep should top dressing be?
The single rule: the grass must still show through after you rake it in. Grass leaves need light; bury them fully and the lawn thins or dies in patches. In practice that means:
| Goal | Depth | Notes |
|---|---|---|
| Light feed after coring / aerating | 5 mm | Brush into the core holes; sandy mix or fine compost. |
| General levelling of a bumpy lawn | 10 mm | The standard job; 1 m³ per 100 m². |
| Aggressive levelling on couch / kikuyu / zoysia | Up to 15 mm | Only when the lawn is growing fast (late spring–summer). |
| Buffalo, fescue, ryegrass | ≤ 10 mm | These recover more slowly – go thinner, more often. |
| Deep hollows (> 20 mm) | Two or three passes | Let the grass grow through between applications, 3–6 weeks apart. |
Sand, soil or compost?
- Washed sand (medium, not fine beach sand) is best for pure levelling and for sandy lawns. It stays loose, drains well and will not change your soil type. Avoid fine sand on clay lawns – it can set like brick.
- Sand/soil or "top dressing" blends (typically 70–80 % sand with screened soil or compost) level and feed at once. This is what most landscape yards sell as "lawn top dress" in Australia and NZ.
- Screened compost feeds and improves clay soils but levels poorly – use 5 mm, and only well-screened product so you are not raking out sticks.
- Never use unscreened garden soil or "fill": the lumps make the lawn bumpier than when you started.
Mow low, dethatch or aerate if needed, spread the mix in small heaps, rake or drag it level with the back of a rake or a lawn leveller, then water it in. Feed a week later once the leaves are through.
Worked example
A 12 m × 8 m kikuyu lawn (96 m²) with a few hollows. You choose 10 mm overall and tick the 10 % allowance:
- 96 m² × 0.010 m = 0.96 m³. Plus 10 % = 1.06 m³ ≈ 1,060 L.
- In 30 L bags: 36 bags at $9 = $324 and a lot of lifting.
- Bulk top dressing at $95/m³ + $70 delivery = $171 for 1.06 m³ (most yards round to 1 m³ or 1.25 m³ – order 1.25 to be safe).
Weight check: a sand-based mix is about 1.4–1.6 t per m³, so this is roughly 1.5 tonnes. A 6×4 trailer can legally carry only about 500 kg, so collecting it yourself means three or four trips; see the trailer load calculator. Laying a brand-new lawn instead? The underlay goes on 100–150 mm deep; use the topsoil calculator, then the turf or grass seed calculator. Feed a week after top dressing with the help of the fertiliser calculator.
Top dressing questions
How much top dressing do I need for 100 square metres?
1 m³ at 10 mm, 0.5 m³ at 5 mm, 1.5 m³ at 15 mm. In 30 L bags that is 34, 17 and 50 bags respectively.
When is the best time to top dress a lawn in Australia?
For warm-season grasses (most Australian lawns), late spring to early summer once the lawn is actively growing – October to December in most regions. Cool-season lawns in southern Australia and New Zealand are best top dressed in early autumn or spring.
Can I top dress with plain sand?
Yes for levelling, especially on sandy soils and golf-style couch lawns. Use a washed medium sand and fertilise separately, because sand adds no nutrients.
Sources and method
- Depth and timing guidance follows the common recommendations of Australian turf producers and lawn-care industry bodies (5–10 mm typical, 15 mm maximum on vigorous warm-season grasses, applied during active growth).
- Coverage figures are geometry (1 m³ = 100 m² at 10 mm) and appear in the table above; bag counts round up.
- Sand density range from landscape-supply price lists (≈ 1.4–1.6 t/m³).
Written by DueRiva · Last reviewed 23 September 2026 · Report an error