A yellow lawn is one of the most common summer frustrations and it can hit even the most cared-for lawn. The good news? Yellowing is usually a symptom, not a disaster. Once you know what’s causing it, you can fix it quickly and stop it from spreading.
Below are the 7 most common reasons Kiwi lawns turn yellow plus exactly what to do next.
1. Your Lawn Is Heat-Stressed
The problem:
Hot days + dry soil = grass that can’t keep up. Blades lose moisture faster than the roots can replace it, turning the lawn pale, straw-like, or patchy yellow.
How to fix it fast:
- Deep water 2–3 times per week
- Water early morning (never at night — fungus risk)
- Add a soil wetting agent if water won’t absorb
- Shade high-stress areas temporarily if possible
Best LAWNZ products:
2. You’re Not Watering Enough (or Evenly)
Dry patches can form from:
- Hydrophobic soil
- Sprinklers missing corners
- Wind blowing water away
- Sunny slopes drying quicker
How to check:
Push a screwdriver into the soil. Hard after 1–2cm? Too dry.
Fast fix:
- Use the cycle–soak method
- Adjust sprinkler angle/coverage
- Core-aerate compacted areas
- Water deeply to reach 15–20cm
3. Lack of Nutrients (Especially Nitrogen & Iron)
If your whole lawn is pale or light yellow, it’s likely a nutrient deficiency.
Common signs:
- Lime-green colour
- Slow growth
- Dull or flat appearance
- No improvement after watering
Quick fix:
Apply a liquid fertiliser with Nitrogen + Iron for fast greening.
Best LAWNZ options:
- Enhance (Nitrogen + Iron + Humics)
- Spark (6% Iron for fast colour)
- Amplify (granular food + long-term feeding)
4. Mowing Issues
Yellowing can also come from:
- Mowing too short (“scalping”)
- Blunt mower blades
- Cutting more than 1/3 of the blade
- Mowing during peak heat
Fix it:
- Raise your mower height
- Sharpen the blades
- Avoid midday mowing
- Water the next morning to help recovery
5. Fungal Disease
Fungus shows up as:
- Yellow patches
- Rings or circles
- Orange/red tinge
- Slimy or wet-feeling soil
Fast fix:
- Stop watering at night
- Improve airflow
- Apply a fungicide
Best LAWNZ product:
- Shield (Azoxystrobin) — broad-spectrum protection
6. Pet Urine (Especially Dogs)
Urine burns appear as:
- Bright yellow circles
- A dark green ring around the edge
- Repeated damage in the same spots
Fix it:
- Flush with water immediately
- Rake lightly
- Overseed or topdress if dead
7. New Lawn Settling (New Home Issue)
New lawns often have temporary yellowing from:
- Patchy roots
- Poor soil contact
- Uneven watering during establishment
Fix:
- Deep water every 2–3 days initially
- Feed gently with Thrive
- Keep off high-traffic areas
How to Tell Which Problem You Have
| Symptom | Most Likely Cause | Fast Fix |
|---|---|---|
| Corners/edges yellow | Sprinkler coverage | Adjust pattern, deeper watering |
| Whole lawn pale | Nutrient deficiency | Apply Enhance or Amplify |
| Circular yellow patches | Fungus or pet urine | Use Shield / flush with water |
| Straw-like, crispy | Heat stress | Deep water + wetting agent |
| Yellow after mowing | Scalping/blunt blades | Sharpen + raise mower height |
| Patchy dry spots | Hydrophobic soil | Core-aerate + cycle–soak |
How to Fix Yellow Grass Fast (Simple Action Plan)
1. Water deeply tomorrow morning
Instant relief for heat stress.
2. Treat hydrophobic soil
Core-aerate + wetting agent.
3. Feed correctly
4. Fix mowing height + blade sharpness
5. Treat fungus if needed
Odd patches or red/orange tone → Shield.
When Yellow Grass Isn’t a Problem
Temporary yellowing is normal:
- After hot days
- After short mowing
- After seasonal changes
- After heavy rain
If soil moisture and nutrients are good, colour usually bounces back.
