How to Get Rid of Lawn Grubs Without Using Harmful Chemicals

How to get rid of lawn grubs without spraying the whole lawn

February 6, 2025

How to get rid of lawn grubs without spraying the whole lawn

Lawn grubs are the larvae of beetles, they sit in the top few centimetres of soil eating grass roots, and by the time you notice them the lawn has usually already gone brown in patches. The part worth knowing before you buy anything is that every lawn has some, the damage comes from the numbers rather than from their existence, and there's a five minute test that tells you which situation you're in.

The signs, in order of how sure they make you

Brown patches that don't green back up after a decent watering are the first hint, and on their own they prove nothing, because dry spots and fertiliser burn and dog urine all look similar from the back step.

Turf that lifts is a much better sign. If you can get your fingers under the edge of a brown patch and peel it back like loose carpet, the roots underneath have been chewed off and something has been eating them.

Birds working the lawn over is the third one. Magpies and starlings pulling at the grass in one spot every morning are finding something, and they're a lot better at locating grubs than we are.

The soapy water test

This is the one that settles it, and it costs nothing. Put a good squirt of dishwashing liquid into a watering can of water and pour it evenly over about a square metre of the affected lawn, then sit and watch for ten minutes. The soap irritates them and anything in there comes up to the surface.

One or two is normal and every lawn in town would give you that. If they keep coming up and up, you have your answer, and the patch you tested is the patch worth treating.

What to do before reaching for anything

A strong lawn carries a grub population without showing it, and a weak one falls over, so most of the fight is the ordinary lawn care you were going to do anyway. Water deeply and less often so the roots go down instead of sitting in the top centimetre where the grubs are. Mow a bit higher, because longer leaf means more root underneath it. Keep the fertiliser up so the lawn can grow back faster than it's being eaten.

Aerating helps too, since compacted soil gives you a shallow root system and a shallow root system is the one grubs can cut through in a week.

Marigolds planted through the nearby beds are worth a go as well. They won't clear an infestation and nobody should pretend they will, but beetles are less inclined to hang around and lay where they're growing, and a packet of seed is cheap enough that it's not much of a gamble.

When a treatment is the honest answer

If the turf is lifting and the soapy water test keeps producing grubs, cultural fixes are not going to save that patch this season. At that point a proper lawn grub treatment is the right call, and the thing to do is treat the affected area rather than the whole lawn, because there's no reason to put product over ground that hasn't got a problem.

Put it on in the evening rather than the middle of the day, water it in afterwards so it gets down to where the grubs actually are, and read the label for the withholding time and keep kids and pets off until it's done. The label is the instruction, not the guide.

Then feed the lawn and oversow the bare patches, because killing the grubs doesn't grow the grass back. That part is still on you.

Shop related products

Lawn Grub & Beetle Kill Hose On 2L. Hose on treatment for an area the test has confirmed.
Neutrog Blade Runner Lawn Fertiliser 15KG. Feed to push the recovery once the damage has stopped.
Brunnings Kikuyu Lawn Seed 1KG. For oversowing the patches that got eaten out.
D.T. Brown Marigold Sparky Mixed, 250 seed pack. Cheap enough to plant through the beds along the lawn edge.

Did you know we also stock grub granules in 500g and a lawn builder grub and insect control in 2.5kg, along with gypsum in 10kg and 20kg for the compacted patches. They're not on the website, so give us a ring on (08) 8536 4333 to check what's on the shelf.

The lawn treatments and the seed are in the garden centre, and if you want to be sure it's grubs before you spend anything, do the soapy water test and come in and tell us what came up.