Understanding NPK: What the Numbers Mean
Every fertiliser displays three numbers (like 20-5-10) representing Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen drives leaf growth and green colour — it is the most important nutrient for lawns. Phosphorus supports root development and is crucial for new lawns. Potassium strengthens the grass against drought, disease, and wear. For established Brisbane lawns, choose a fertiliser with high nitrogen (first number) and moderate potassium (third number). New lawns and renovation projects benefit from higher phosphorus (second number).
Best Lawn Fertilisers for Brisbane
| Product | NPK Ratio | Type | Feeds For | Best For |
|---|---|---|---|---|
| Scotts Lawn Builder | 23-2-4 | Slow-release granular | 8–12 weeks | Set and forget — great all-rounder |
| Yates Dynamic Lifter | 3.7-2-1.8 | Organic granular | 6–8 weeks | Improving soil health, safe around pets |
| Seasol PowerFeed | 12-1.4-7 | Liquid concentrate | 2–4 weeks | Quick green-up, foliar feeding |
| Lawn Solutions Fertiliser | 19-1.6-12.6 | Controlled-release granular | 10–12 weeks | Premium lawns, Couch and Buffalo |
| Charlie Carp | 8-1-5.6 | Liquid organic | 4–6 weeks | Organic option, fish-based |
When to Fertilise in Brisbane
Brisbane's warm subtropical climate means grass grows actively from September through April. Time your fertiliser applications to match this growth cycle. First application in early spring (September) as the lawn breaks winter dormancy — this is the most important feed of the year. Follow up with applications every 6–10 weeks through summer (November, January, March). The last application should be in early autumn (March–April) to help the grass store energy for winter. Do not fertilise in winter (May–August) — dormant grass cannot use the nutrients, so you are just feeding weeds and wasting money.
How to Apply Granular Fertiliser
- 1
Mow first
Mow the lawn 1–2 days before fertilising so the granules reach the soil surface. Do not mow immediately after fertilising as you will pick up the granules.
- 2
Calibrate your spreader
If using a broadcast spreader, check the product label for the correct setting. If hand-spreading, mark out 10m² areas and weigh the correct amount per area — this prevents over-application, which burns the lawn.
- 3
Apply in a grid pattern
Walk at a steady pace in parallel strips, slightly overlapping each pass. Then repeat at 90 degrees for even coverage. Uneven application creates dark green stripes (over-fertilised) and pale stripes (under-fertilised).
- 4
Water in thoroughly
Apply 10–15mm of water immediately after spreading. This washes granules off the leaf blades (preventing burn) and activates the fertiliser. If rain is forecast within 24 hours, skip the manual watering.
Pro Tip
The most common mistake is applying too much fertiliser. More is not better — excess nitrogen burns grass, creates excessive thatch, and encourages fungal disease. Always follow the product label rates. If in doubt, apply at half the recommended rate twice (4 weeks apart) rather than the full rate once.
Common Fertilising Mistakes
- •Over-applying — causes fertiliser burn (yellow or brown patches), excess thatch, and pollution
- •Fertilising in winter — dormant grass cannot absorb nutrients, you are just feeding weeds
- •Not watering in — granules sitting on leaves in hot sun will burn the grass
- •Using the wrong product — high-phosphorus fertiliser on established lawns promotes weeds
- •Inconsistent application — causes stripy, uneven colour across the lawn
- •Fertilising stressed or drought-affected lawn — water and recover first, then feed
Want a professionally maintained lawn without the guesswork? We include fertilising advice as part of our ongoing lawn care service.
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