How to Choose a Lawn Fertiliser (Buffalo, Couch & Kikuyu)

Key Takeaway: There is no single best lawn fertiliser, only the right format and nutrient profile for your grass and your soil. Granular slow-release products suit most home lawns with the lowest burn risk, liquid feeds suit a quick correction or hard-to-reach spot, and organic pelletised products build up soil over time at a lower nutrient concentration. Buffalo needs meaningfully more nitrogen than couch or kikuyu, and a seaweed-based tonic is a soil conditioner, not a substitute for an actual NPK feed.

Walk down the fertiliser aisle and the choice is genuinely confusing: granular or liquid, fast or slow-release, organic or synthetic, a generic lawn blend or something formulated for your specific grass. The right answer depends on what you are trying to fix and what grass you actually have, not on picking whichever bag looks most convincing.

NPK: What the Numbers on the Bag Mean

The three numbers on any fertiliser bag are nitrogen, phosphorus and potassium, in that order, as a percentage of the total product. Nitrogen (N) drives leaf growth and green colour, which is why a spring green-up product leans heavily on it. Phosphorus (P) supports root establishment, and matters far more for a new lawn than an established one. Potassium (K) supports general hardiness and stress tolerance, which is why it features more heavily in a pre-winter feed. Northern Territory Government guidance puts a suitable general lawn ratio at roughly 15:5:10, nitrogen well ahead of phosphorus and potassium, which reflects how little phosphorus an established lawn actually needs.

That last point carries real legal weight in some states. Western Australia caps phosphorus in lawn and all-purpose fertiliser at 1% by law, specifically to cut the nutrient runoff reaching the Swan-Canning river system and other waterways, after excess phosphorus was found to be triggering algal blooms. If you garden anywhere near a waterway-sensitive catchment, a low-phosphorus lawn product is not just good practice, it may be a legal requirement where you live.

Granular, Slow-Release, Liquid or Organic

Type	How it behaves	Best for	Watch out for
Fast-release granular	Nutrient available almost immediately	A quick spring green-up	Highest burn risk if over-applied or not watered in
Slow-release (coated) granular	Nutrient released gradually over weeks	Set-and-forget feeding with lower burn risk	Slower to show a visible result
Liquid or soluble	Absorbed quickly through soil and leaf	Small areas, a quick correction, hard-to-reach spots	Needs more frequent reapplication, easy to over-dilute or under-dilute
Organic pelletised	Slow-release, also feeds soil biology	Building up poor soil over time	Lower nutrient concentration, often needs more product for the same result
Seaweed-based tonic	Biostimulant, not a true NPK fertiliser	Root development and stress recovery alongside a real feed	Will not replace a fertiliser on its own

For most home lawns, a slow-release granular product is the easiest starting point: fewer applications, lower burn risk, and no dilution to get wrong. Liquid feeds earn their place for a fast, targeted fix rather than as the whole feeding program.

Buffalo, Couch and Kikuyu Don’t Need the Same Feed

Buffalo is the clear outlier. The federal Office of the Gene Technology Regulator’s own biology assessment puts the Sir Walter cultivar’s optimum nitrogen requirement at around 200kg per hectare per year, noticeably more than a generic lawn baseline, to hold its colour. Couch and kikuyu generally do well on a more standard balanced feed. If you are not sure which of the three you actually have, our guide on how to identify buffalo, kikuyu and couch grass covers that first, and our full guide on when and how often to fertilise your lawn covers the actual timing and application rate in depth.

Choosing a Spreader

Drop spreader: releases product in a precise strip directly beneath it, minimal risk of overshooting onto paths or garden beds. Suits smaller, regular-shaped lawns where precision matters more than speed.
Broadcast or rotary spreader: throws product in a wide arc, covering ground much faster. Suits larger or irregularly shaped lawns, but is more likely to send product onto a driveway or path, where it can wash into a stormwater drain instead of feeding the lawn.
Handheld or shoulder spreader: good for small areas, patch repairs, or awkward corners a wheeled spreader can’t reach.
Hose-end or watering-can application: the standard way to apply a liquid or soluble fertiliser evenly without a dedicated spreader.

Whichever spreader you use, work in two directions at right angles rather than one pass, and sweep any product that lands on a hard surface back onto the lawn rather than hosing it into the gutter.

Buying in Bulk

A bulk bag is usually cheaper per kilogram for a larger property, but check two things before assuming it is a straightforward discount. First, confirm the NPK analysis matches the smaller retail bag you were comparing it against, since bulk blends are not always the same formulation. Second, store it somewhere dry and sealed: granular fertiliser absorbs moisture from the air and clumps or cakes over time, which makes it far harder to spread evenly later.

[INTERNAL LINK OPPORTUNITY: link to the Weeds, Pests & Feeding pillar, “Lawn Weeds, Grubs and Fertilising: The Complete Australian Guide”, once published.]

Frequently Asked Questions

What is the best lawn fertiliser?

There is no single best option. A slow-release granular product suits most home lawns with the lowest burn risk, liquid feeds suit a quick fix, and organic pelletised products build up poor soil over time. The right choice depends on your grass type and what you’re trying to achieve.

What does NPK mean on a fertiliser bag?

NPK stands for nitrogen, phosphorus and potassium, listed as percentages in that order. Nitrogen drives leaf growth and colour, phosphorus supports root establishment, and potassium supports hardiness and stress tolerance. Lawns generally need far less phosphorus than a general garden fertiliser provides.

Is organic lawn fertiliser as effective as synthetic?

Organic pelletised fertilisers release nutrient more slowly and at a lower concentration than synthetic granular products, so they often need to be applied more heavily or more often for the same visible result, but they also build up soil biology over time and carry a lower burn risk.

Do buffalo, couch and kikuyu need different fertiliser?

Buffalo needs noticeably more nitrogen than couch or kikuyu to hold its colour, according to federal government biology research on the species. Couch and kikuyu generally do well on a more standard balanced lawn feed.

Is seaweed tonic a fertiliser?

Not really. Seaweed-based products are biostimulants that support root development and help a lawn recover from stress, but they don’t supply meaningful nitrogen, phosphorus or potassium. Use one alongside a real fertiliser, not instead of one.

Sources