A thin lawn is a weed problem waiting to happen. Bare soil between grass plants is an open invitation to broadleaf weeds, summer grass and moss, and once they're in, you're fighting them every season instead of just mowing.
Overseeding fills those gaps with new grass plants. It's a fraction of the cost of ready lawn, and on a lawn that's structurally sound but tired it will do the job properly.
What's included
- Assessment of soil, drainage, shade and existing grass type
- Weed control ahead of sowing where needed
- Scarifying or dethatching to expose soil for seed contact
- Aeration on compacted lawns
- Seed blend matched to sun, shade, wear and soil
- Sowing, light topdressing and starter fertiliser
- Written watering and first-mow schedule
Timing decides the result
In Auckland, autumn is the best sowing window — roughly March through May. The soil is still warm from summer so seed germinates fast, the rain does most of the watering, and the new grass has the whole cool season to establish before it faces heat.
Spring sowing (September–October) is the second-best option, but new seedlings then have to survive their first summer with a small root system, and they're competing with summer weeds germinating at the same time. Sowing in the middle of summer almost never works without irrigation.
Getting seed to actually touch soil
Seed scattered on top of thatch and existing grass mostly feeds birds. For germination you need seed-to-soil contact, which means scarifying or dethatching first to open the surface, then a light topdressing to hold the seed in place and stop it drying out.
On compacted lawns — heavy clay, or areas that get parked on — we aerate first. Roots can't push into soil that a screwdriver won't go into, and no amount of seed fixes compaction.
Choosing a seed blend
Full sun with kids and a dog wants a hard-wearing rye and fescue blend that repairs quickly. A formal front lawn that's mostly looked at can carry a finer fescue for a better colour and finer leaf. Shaded areas need a high proportion of creeping red fescue, which tolerates lower light than anything else that will grow here.
One practical warning: overseeding a kikuyu lawn with rye or fescue is usually temporary. Kikuyu is aggressive and will crowd the new grass out by the following summer. On a kikuyu lawn the better spend is usually fertiliser and correct mowing height rather than seed.
Grass Seeding — common questions
When is the best time to sow grass seed in Auckland?
Autumn — March to May — is the best window. The soil is still warm so seed germinates quickly, autumn rain does most of the watering, and the new grass has the whole cool season to establish before facing summer heat. Spring sowing works but is harder.
How long does grass seed take to germinate?
In warm autumn soil, ryegrass shows in about 5–10 days and fescue in 10–14 days. The lawn looks patchy for the first month and fills in over 6–8 weeks. Keep the surface consistently damp for the first three weeks — if the seed dries out once it has swollen, it dies.
Is overseeding cheaper than ready lawn?
Yes, though the gap is narrower than most people expect. Overseeding starts at $20 per square metre against $30 per square metre for supplied and laid ready lawn. The bigger trade-off is time — seed takes a full season to look established, where ready lawn is finished on the day it's laid.
Can you fix a lawn that's mostly weeds and moss?
Yes, but it needs a full renovation rather than just seed. Moss signals shade, compaction or poor drainage, and unless those causes are dealt with it comes straight back. We assess the underlying cause first and quote the fix, not just the symptom.