When to fertilise your lawn in Australia (by grass type)

Fertilising questions are nearly always timing questions. On the warm-season lawns most Australians own, the same bag of fertiliser is a great decision in October and a waste of money in June — or worse than a waste, because feeding at the wrong time feeds weeds, pushes soft disease-prone growth, or dumps nutrient straight through dormant turf into the stormwater. (Cool-season lawns run a different calendar — covered below.)

Here's the timing logic I actually use, by grass type and season. Southern-hemisphere seasons throughout, obviously: summer is December–February, autumn March–May, winter June–August, spring September–November.

The one rule that drives everything

Feed a lawn when it's actively growing, and don't feed it when it isn't. Fertiliser isn't medicine for a struggling lawn — it's fuel for a growing one. A dormant or stressed lawn uses little of the nitrogen you give it, and uses it inefficiently at best.

For the warm-season grasses that dominate Australian lawns — Buffalo, Couch, Kikuyu, Zoysia — active growth runs roughly spring through autumn, peaking in summer. For cool-season lawns (tall fescue, Kentucky bluegrass, ryegrass blends, common in Melbourne, the ranges and Tasmania) the calendar is inverted: they grow hardest in autumn and spring, limp through summer, and stay green in winter.

Warm-season lawns (Buffalo, Couch, Kikuyu, Zoysia)

Spring — the first feed of the year. Wait until the lawn has properly woken up: soil warm, lawn visibly growing, you've already mowed a couple of times. In south-east Queensland that can be September; in Melbourne or Canberra it's more like October, after frost risk has passed. Feeding a lawn that's still half-dormant mostly feeds the winter grass and broadleaf weeds sitting in it. If you're renovating in spring, fertiliser comes after the mechanical work — the full sequence is in spring lawn renovation, in order.

Summer — maintenance feeding, with heat sense. The lawn is at peak growth and can use regular feeding, but never apply fertiliser to a heat-stressed or bone-dry lawn, and always water it in properly — granular fertiliser sitting on dry leaf in 35 °C heat is how lawns get burnt. If a heatwave is forecast, wait for the other side of it.

Autumn — the most underrated feed of the year. A feed in early-to-mid autumn, while the soil is still warm, is what carries colour and density into winter and fuels early spring recovery. In the subtropics you can feed later into autumn than in cool climates. As a rule of thumb, the last proper feed happens while the lawn is still actively growing — roughly April in most of the country, earlier where frosts come early.

Winter — put the spreader away (almost everywhere). Across most of the country, warm-season grasses slow right down or go fully dormant, and nitrogen now does very little for the lawn. The exception is the frost-free tropics and the warmest subtropical pockets, where warm-season lawns keep visibly growing through winter — there, the core rule still governs: a lawn that's actively growing can take a light feed. Everywhere else, if you want winter colour: on a lawn that's still ticking over, an iron-based product can deepen colour without pushing growth — though it won't wake a fully dormant lawn — and Couch and Kikuyu owners in cooler areas sometimes oversow with ryegrass in autumn instead (Zoysia and Buffalo aren't oversowing candidates; pigmented colourants exist for those).

The per-grass differences that matter

• Kikuyu is the heaviest feeder of the lot — it responds to (and demands) more regular feeding than anything else, and repays it with the fastest recovery from wear.
• Couch is also a solid feeder and rewards a regular, consistent program — hungry Couch thins out and lets weeds in.
• Buffalo (Sir Walter and friends) sits in the middle: regular but moderate. If you're chasing colour on Buffalo, mowing height and iron do as much as extra nitrogen — more on that in the Sir Walter Buffalo care guide.
• Zoysia is the light feeder — it genuinely needs less fertiliser than the others, and overfeeding it mostly buys you thatch, not colour. Feed it less often and less heavily than you would a Couch or Kikuyu.

Cool-season lawns (fescue, bluegrass, rye)

Everything above, flipped. The two big feeds land in autumn (the most important one — it repairs summer damage and builds the plant for the year) and spring. Through summer, hold the nitrogen: pushing soft growth in heat is how cool-season lawns get wiped out by disease and drought stress — summer is for mowing high and watering deep, not feeding. A light winter feed is fine in most regions because the grass keeps growing.

What to actually put on

Product choice matters less than timing, but the honest basics: nitrogen is what drives most of the visible response in established turf, and a quality granular lawn fertiliser delivers it evenly; slow-release blends buy you evenness between applications; liquid feeds act fast but don't last. Whether your lawn actually needs much phosphorus or potassium is a soil question, not a guess — a soil test is what tells you that (and pH, which decides whether the nutrients you spread are even available to the plant). The application rate on your product's bag is the authority — follow it, don't freestyle it. More is not better: I've put a stripe into my own lawn double-passing with the spreader in a hurry, and once was plenty. Water granular product in after spreading.

One extra worth knowing: if an actively growing lawn yellows despite feeding, the gap can be iron rather than nitrogen — a deficiency worth confirming before you respond by simply feeding harder.

The part everyone gets wrong: remembering

None of this is hard. What's hard is that the right week for the first spring feed depends on your grass type and your climate zone, the autumn cutoff moves by a month between Brisbane and Hobart, and nobody remembers any of it in the right week — which is most of why I built LawnSuite. The app runs free in the browser (no install), and the free side includes LawnSuite's dosage calculator — it works out how much product your measured lawn area needs from the rate printed on your bag, so you never freestyle an application. The year-round feeding program — every feed for your grass type and climate zone, scheduled to the right week with reminders — is the Pro side.

And if your lawn is yellow or patchy and you're not sure feeding is the answer — it often isn't — start with how to tell what's actually wrong with your lawn before you spend the money.