How to Control (and Hopefully Eliminate) Prickle Weed from Your Lawn in New Zealand

How to Control (and Hopefully Eliminate) Prickle Weed from Your Lawn in New Zealand

If you’ve ever been jabbed in the foot while walking barefoot across your lawn, there’s a good chance you’ve encountered Soliva sessilis - commonly known here in New Zealand as prickle weed or Onehunga weed.

This annoying lawn invader is small, spiny, and spreads fast if left untreated. While it’s originally from South America, it’s now widespread across Aotearoa, particularly in lawns and paddocks that are thin, compacted, or under stress during the warmer months.

Why Prickle Weed is a Problem in Kiwi Lawns

• It germinates in autumn, grows through winter, and sets seed in late spring.

• The seed heads dry out and become sharp barbs, turning summer lawns into barefoot hazards.

• It thrives in common New Zealand lawn types like ryegrass, fine fescue, and browntop - especially when grass coverage is poor or soil is compacted.

How to Control Prickle Weed Effectively in NZ Conditions

1. Timing is Everything - Treat in Autumn or Early Winter
Prickle weed begins germinating in March to May. The best window for control is from late autumn through winter, before it matures and sets seed in spring (usually around October - November). By summer, it’s too late - the seeds have already hardened and are waiting to spread.

2. Use a Selective Herbicide
Look for a selective broadleaf herbicide that targets Onehunga weed without damaging your turf. In New Zealand, products containing MCPA and Dicamba, or a broad-spectrum weed killer like Tordon Brushkiller, are often effective.

Apply on a dry day with no rain forecast for at least 6 hours. Reapply in 3 - 4 weeks if needed.

3. Improve Lawn Density
A thick, healthy lawn naturally chokes out prickle weed. To strengthen your turf:

• Overseed patchy areas in spring or autumn with a hardy lawn mix (ryegrass/fine fescue blend)

• Fertilise in early spring and autumn

• Avoid scalping your lawn - mow regularly, but not too short

4. Aerate and Topdress
Prickle weed thrives in compacted soil. If your lawn feels hard underfoot or puddles in spots, consider aerating and topdressing with compost or sand in autumn to improve drainage and root health.

Can You Eliminate It Completely?

With consistent treatment across a couple of seasons and improved lawn health, yes - you can drastically reduce or even eliminate prickle weed. But letting it go to seed even once can start the cycle all over again.

Let Mahurangi Mowers Help

At Mahurangi Mowers, we understand the challenges of rural lawn care - especially when it comes to persistent pests like prickle weed. If you’d like help tackling problem areas, seasonal spraying, or just want a hand keeping your section under control, we’re here for it.

Get in touch today and let’s get your lawn back to being a barefoot-friendly zone.

Symon @ Mahurangi Mowers.