Why does my new lawn have dry patches? (Diagnosing the 5 common causes)

Dry patches in a new lawn are stressful. You've just paid for fresh turf and three months in there's a patch of brown grass in the middle of an otherwise green lawn. Here are the five most common causes we see in Melbourne's south-east and how to tell which one is yours.

Quick triage

Cause 1: Hydrophobic soil

The most common cause of dry patches in Melbourne's south-east, especially on newly laid lawns over clay or reclaimed builder soil.

What's happening: the topsoil has dried out so completely that it now actively repels water. Pour water on it and it beads up and runs off instead of soaking in. The grass on top can't get water no matter how much you irrigate.

How to confirm: at the dry patch, dig a small hole 100mm deep. Pour water into the hole. If the water sits there for more than 5 minutes without soaking in, you have hydrophobic soil.

Fix:

1. Apply a wetting agent (Sub-Air, Soil Solver, EcoH2O) at the recommended rate
2. Water in thoroughly with low-pressure soaking, not high-pressure spray
3. Repeat in 4 to 6 weeks
4. For severe cases, fork-aerate the patch first to break the crust

A bag of granular wetting agent at Bunnings is about $35 and treats 200m². The fix is cheap and usually works within 2 to 3 weeks.

Cause 2: Shade (too little sun)

If the patch is in shade for more than half the day, your turf variety might be wrong for the location.

Sir Walter Buffalo tolerates 4 to 5 hours of sun. Kikuyu needs 6+ hours. Couch needs 6+ hours.

If you have Kikuyu or Couch in a shaded zone, the turf will thin out and brown within 6 to 18 months. There's no fix short of replacing the patch with a shade-tolerant variety. Sir Walter laid into a shaded patch usually establishes well.

How to confirm: track the sun across the patch on a clear day. If it's getting less than 4 hours of direct sun, that's the issue.

Fix:

1. For Kikuyu or Couch: replace the patch with Sir Walter
2. For Sir Walter in deep shade: consider removing the lawn entirely in that zone and converting to a garden bed or shade-tolerant ground cover (Trachelospermum, Liriope)
3. Thin out overhead branches if practical

Cause 3: Seam dryness from poor laying

If you see yellow or brown stripes that follow the lines where two turf rolls were laid against each other, this is a laying issue.

What's happening: the seams weren't laid tight enough, so the edges of the rolls dry out faster than the centres. The grass at the edges has no soil contact.

How to confirm: look at the dry zone. If it's a clean straight line about 5 to 15cm wide, that's a seam.

Fix:

1. Press down on the affected strip with body weight to push it into contact with the soil
2. Top dress with a thin layer (5 to 10mm) of quality topsoil along the seam
3. Water heavily for the next 7 to 10 days

A good installer lays seams tight and there should be no visible joins after 4 to 6 weeks. If you have visible seams after 3 months, that's a quality issue worth raising with the installer.

Cause 4: Fungal disease or pet urine

Round patches 30 to 60cm across, often with a slightly raised brown ring, are usually one of two things in Melbourne south-east lawns.

Dollar spot fungus: small round patches (5 to 10cm across), straw coloured, with a frayed edge. Common in autumn and spring on Buffalo and Couch.

Brown patch fungus: larger round patches (20 to 60cm across), brown to grey, with a slightly darker rim. More common in warm humid weather.

Pet urine burn: round patch, very brown in the centre, often darker green ring around the edge (the diluted edge gets a nitrogen boost). Always associated with where the dog goes.

Fix for fungus:

1. Stop watering at night (creates conditions for fungal spread)
2. Improve airflow by trimming nearby shrubs
3. Apply a fungicide (Mancozeb, Eco-Fungicide) per label
4. Reduce nitrogen fertiliser if you've been heavy-handed

Fix for pet urine:

1. Water the patch deeply within an hour of urination (dilutes the nitrogen)
2. For chronic spots, install a low-fenced "dog toilet" area on bark or pebble
3. Once a patch is dead, scrape, top dress, re-seed or re-turf

Cause 5: Soil compaction

If the dry patch is exactly where you walk every day (gate to door, washing line route, around the kids' trampoline), the soil is probably compacted.

What's happening: compacted soil has no air pockets, water can't move through it and roots can't penetrate it. The grass on top suffers.

How to confirm: push a screwdriver into the soil at the patch and at a healthy area. If the patch resists noticeably more, that's compaction.

Fix:

1. Aerate the patch with a garden fork or hire a coring aerator
2. Spread a thin top dress of compost or quality soil
3. Water in deeply
4. Reroute foot traffic if possible (stepping stones, a paved path)

For repeat compaction in a high-traffic zone, the long-term fix is paving. Installing a row of stepping stones or a path where people walk reduces the wear and keeps the lawn intact.

What you should never do

A few things we see homeowners do that make patches worse:

• Don't overwater. Soggy patches turn into fungal patches. Water deep and infrequent.
• Don't pile sand on a patch to "level it." Sand on top of clay makes a perched water table that suffocates roots.
• Don't reseed a Sir Walter patch with seed. Sir Walter is propagated by runner, not seed. Buy Sir Walter plugs or rolls for repair.
• Don't fertilise a struggling lawn. A stressed lawn can't absorb the nutrients and excess fertiliser burns the roots.

When to call us

If you've tried the obvious fixes and the patch is getting worse, or if the issue covers more than a quarter of the lawn, it's worth a site visit. Recurring patches often trace back to a drainage, soil or laying issue that needs proper diagnosis rather than spot treatment.

• Browse our turf installation service
• See work in Clyde North, Officer and Pakenham
• Call (03) 4328 2781 or request a quote