Feeding your lawn in spring: what to do and what to skip

Warm season grasses can't use much feed until the soil has warmed up and they're actively growing. Feed too early, while the lawn is still half asleep, and most of it goes to waste.

The sign you're looking for is new growth. When the lawn starts greening up and you're mowing more often, it's ready to use a feed.

Fertilise Wise, a Perth program that promotes lawn feeding practices that protect local rivers, recommends feeding only in spring and early autumn (September, October, November, March and April) and not in summer or winter.

A feed only works if water carries it down to the roots. If your sand has gone water repellent, water beads and runs off, and the fertiliser goes with it or just sits on top.

That's why a wetting agent often comes before, or alongside, a spring feed on Perth lawns. If you're not sure whether your soil is repelling water, our post on hydrophobic sandy soil explains how to tell. And if the ground is hard and compacted, core aeration opens it up so water and feed can get in.

Slow release fertilisers break down over weeks rather than days. On sandy soil that's a big advantage, because the lawn gets a steady supply instead of one big hit that mostly drains away.

Low phosphorus matters in Perth. Nutrients from gardens and lawns can make their way into local rivers and wetlands, and phosphorus is a big part of that. Fertilise Wise recommends a complete lawn fertiliser with an N:P:K ratio of around 10:1:6, which means it's high in nitrogen, low in phosphorus and has some potassium.

The bag rate is a maximum, not a target. Fertilise Wise puts the maximum single application at 25 grams per square metre for couch and 12 grams per square metre for kikuyu and buffalo.

Little and often beats a heavy dose. Two lighter feeds across spring do more for a sandy lawn than one big one in September, because the lawn can actually use what it's given.

Apply granular fertiliser on or just before your watering day, then water it in properly so it moves off the leaf and into the soil. Fertiliser left sitting on the leaf in hot sun can scorch it.

Before you water, sweep any granules off paths, driveways and paving back onto the lawn. Anything left on hard surfaces washes straight into the stormwater drains.

A lawn that's dry, heat stressed or dormant can't use fertiliser properly. Feeding it just adds salts to dry soil and pushes growth the roots can't support. Water it back to health first, then feed.

New turf shouldn't be fed until it has rooted in. Until the roots are down in the soil, there's nothing to take the feed up. Our first six weeks guide covers when to start.

If part of the lawn is thin because it's in shade, more fertiliser won't fix it. The limit there is light, not food, and heavy feeding in shade tends to produce soft, weak growth. We've covered what does work in why your lawn is thinning under the trees.

A heavy dose of fast acting nitrogen can turn a lawn bright green in a week. It also pushes soft, fast growth that needs more mowing and more water, and it fades just as quickly. Steady colour and density come from a steady program, not a single hit.

Wait until the lawn is growing. Fix the water first. Use a slow release, low phosphorus fertiliser at or below the recommended rate. Water it in on your watering day and sweep the spills back onto the lawn. Skip feeding stressed lawns, brand new turf and shaded patches, and don't chase a quick green.

Feeding is one of those jobs that's easy to get slightly wrong every year. Our lawn fertilising and lawn aftercare programs match the feed to your grass, your soil and the time of year, so the lawn gets what it can use, when it can use it. Tell us about your lawn through the quote form and we'll reply within one business day with a program tailored to your turf, not a template.