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

Feed when your grass is actively growing: mainly spring through autumn for Buffalo, Couch, Kikuyu and Zoysia, and mainly autumn and spring for cool-season lawns. The seasonal and per-grass logic below gets you to the right month; the label on your bag and the weather in front of you get you to the right day.

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.

The readiness signals I use for that first feed — real growth, soil temperature and frost — are in the first feed of spring.

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).

One trap if you're in the autumn-oversowing camp: check any pre-emergent you've put down (or plan to) against its label's reseeding restrictions before you sow — the timing detail is in pre-emergent timing and soil temperature.

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.

When to fertilise Buffalo grass

Buffalo runs the warm-season calendar above — first feed once it's visibly growing in spring, maintenance feeding through summer, an autumn feed while the soil is still warm, then nothing over winter unless you're in the frost-free north and it's still going. Where Buffalo differs is the ceiling: it's a moderate feeder, so once the lawn is fed and growing, extra nitrogen mostly buys you more mowing, not more lawn.

And pale Buffalo isn't automatically hungry Buffalo. Before you feed a yellowing lawn, rule out the boring causes first — dry soil, shade, compaction — and remember the colour point from the list above: mowing height matters, and iron can help where a deficiency is confirmed; extra nitrogen is not a cure for every pale lawn. Feed it when it's growing; troubleshoot it when it isn't.

Couch, Kikuyu and Zoysia: same calendar, different appetites

The seasonal logic is shared; the appetite isn't. The short version is in the bullet list above — in practice:

• Kikuyu is the heavy feeder here, but let the lawn set the pace: if you're mowing constantly and the catcher is full, it doesn't need another feed, however keen it looks.
• Couch rewards consistency over quantity — regular feeds at the label interval through the growing season beat one big rescue application, which mostly pushes a flush of soft growth the mower then removes.
• Zoysia is the one to underfeed rather than overfeed: pushing excess growth can build thatch and buy you a dethatching job down the track. Feed it less often than your Couch or Kikuyu neighbours feed theirs.

None of this changes how much goes on per application — that's the label's call. It changes how often you reach for the bag.

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.

How often should you fertilise a lawn in Sydney?

Use the grass's appetite and the product's labelled repeat interval through the growing season, not a monthly ritual. Sydney warm-season lawns follow the spring-to-autumn calendar above: wait for the return to regular mowing, then feed while the lawn can use it. A hungry Kikuyu can justify more feeds across the season than a Zoysia, and slow-release and quicker-release formulations run on different repeat intervals. Write down what you applied and when, so a second product doesn't land while the first is still releasing.

Two traps to watch in Sydney. A fescue or ryegrass lawn still runs the inverted calendar above; living in Sydney doesn't turn it into Couch. And don't spread with heavy rain forecast: fertiliser washed off a lawn in a downpour is feeding the stormwater, not the grass. Feeding by species and active growth is also the approach in UC's turf-fertilising guidance — its month tables are Californian, so take the principle, not the dates.

When is the best time to fertilise a lawn in Perth?

Start with the first sustained spring growth, keep feeding through the warm growing months at the label's interval, and fit the autumn feed in while the lawn is still growing. Water Corporation's lawn-care guidance uses spring and the warmer months as its maintenance frame — the lawn still needs to be awake, not just the calendar.

The local wrinkle is sand and water. On sandy coastal-plain lawns, over-watering can carry nutrients below the roots, so follow the label's watering-in directions instead of adding a long soak for luck. Check your rostered sprinkler days and times before spreading; hand-watering is permitted on any day with a watering can or attended hose with a nozzle if it can meet the product label. The winter sprinkler switch-off still applies through 31 August.

The summer rule stands: don't feed a dry or heat-stressed lawn. If it yellows, check the moisture and growing conditions before assuming another feed will fix it; cool-season grass keeps its summer stress-protection calendar here too.

What about new turf or a weed-and-feed product?

New turf runs on establishment rules, not the calendar above. Follow the turf supplier's establishment program — and the label on whatever product it specifies — until the lawn is established for the product's intended use, then move it onto the normal schedule for its grass type. A brand-new lawn doesn't need a feed because yours is due.

A weed-and-feed is two jobs sharing a bag, and only one of them is fertiliser. The feeding half follows everything above; the herbicide half plays by its own rules — the label must list your grass type (some lawn herbicides will damage Buffalo), the weed you're targeting, and the season it works in. If the lawn needs nutrients but not herbicide, buy a plain fertiliser; if the weeds are the real problem, check that this is even their control window. Don't stack a weed-and-feed on top of a regular feed to save a weekend — the label's interval is the authority on when either product goes down again.

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.

That fast-liquid rule of thumb is about quick-release feeds: some liquid formulations also contain slow-release nitrogen, as Penn State's fertiliser guide explains. Check the formulation and follow the specific label for repeat intervals and watering-in; liquid or granular on its own does not settle either question.

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.

If you are comparing the N-P-K analysis on two fertilisers, use the free NPK oxide-to-elemental converter.

For a product-label calculation on a measured lawn, work out how much you need with the free Label Rate Calculator.

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.