The most reliable way to get rid of onion weed is to remove it before it flowers and sets seed, digging out the whole clump with its bulbs or treating it with a registered herbicide used exactly as the label directs. Late winter to spring, when it is actively growing, is the best time to act in Sydney.
This guide explains how to identify it, what kills it, how to treat it in lawn, what it costs to hire help and how to stop it returning.
Key points
- Onion weed (Nothoscordum) grows from small bulbs and spreads by seed, so mowing alone only hides it.
- Hand digging works for small patches if you remove the bulbs and bin the clumps, and herbicides work only when the label lists the weed and your lawn type.
- Home remedies such as vinegar, salt, boiling water and bleach are non-selective and can damage soil, grass and nearby plants.
- Professional weed removal in Sydney typically costs about $75 per hour (October 2026), and paid weed spraying in NSW needs the right EPA licence.
What is onion weed?
| Term | Meaning | Why it matters |
|---|---|---|
| Nothoscordum | A bulb-forming weed (Nothoscordum borbonicum) with strappy leaves and small white, star-shaped flowers | Spreads in lawns and garden beds, and is hard to remove if bulbs remain |
| Bulblets | Small bulbs that form around the parent clump | Break off easily and regrow if you leave them in the soil |
| Flowering and seeding | Flowers appear in late winter to spring, followed by seed | Treat before seeding to stop new plants |
| Dormancy | Leaves die back in hot, dry weather | It can look gone in summer but return in autumn |
Onion weed vs onion grass and other lookalikes
Many Sydney gardeners use onion grass and the other name for the same plant, but they are not always the same weed. Identify it before you treat it.
| Plant | Leaves | Flowers | Notes |
|---|---|---|---|
| Onion weed (Nothoscordum) | Flat, soft, strappy | White with a pale stripe, in clusters | Forms bulbs and bulblets in the soil |
| Onion grass or Guildford grass (Romulea) | Thin, rush-like, almost round | Pinkish-purple, opening in sun | Produces small corms and seeds heavily in winter lawns |
| Three-cornered leek (Allium triquetrum) | Triangular stem | White, drooping bells | A different weed that needs separate advice |
| Native lomandra or dianella | Tough, strappy leaves | Small clusters | Not a weed, so don’t dig it out by mistake |
| Unsure of the plant | Take a sample to a nursery or council weed officer | Do not eat it | Positively identify any plant before eating it |
How to get rid of onion weed in lawn
Treat small patches by hand and large infestations with the right product. Start when the soil is damp and the plants are actively growing.
- Water the area the day before so the soil is soft.
- Loosen the soil around each clump with a trowel or hand fork, then lift the whole clump and its bulbs.
- Sift loose soil for bulblets and remove as many as you can find.
- Bag the clumps and put them in the garden-waste or general bin, not the compost heap.
- Patch the bare spot with compost and seed or turf, because bare soil invites new weeds.
- Check the area every two weeks and remove regrowth immediately.
How to kill onion weed: what kills onion weed
| Method | Effective? | Trade-offs |
|---|---|---|
| Hand digging | Yes, if the bulbs are removed | Slow on big areas; leftover bulblets regrow |
| Registered herbicide | Yes, when the label lists the weed | Follow the label; some products harm certain lawn types |
| Mowing | Not on its own | Keeps flower stems down but leaves the bulbs |
| Smothering with mulch or covers | Partly | Bulbs can push through; suits garden beds, not lawn |
| Boiling water | Kills top growth only | Non-selective, harms grass and soil life, and bulbs survive |
| Vinegar | Burns foliage only | Non-selective and won’t kill the bulbs; see how to kill weeds naturally |
| Salt or bleach | Not recommended | Harm soil long term and damage nearby plants |
Herbicide for onion weed: using it safely
A herbicide for onion weed must be registered for the weed and for your lawn species. Never guess, because buffalo, kikuyu and couch react differently to different products.
- Read the label for the weed name, the target lawn type, application timing and rainfall requirements, and follow it exactly.
- Wear the protective equipment the label lists, and keep children and pets off treated areas until the label says it is safe.
- Don’t spray in wind or before rain, and keep runoff out of drains and waterways.
- Don’t mix products or use one off-label; the label is the only source for rates and methods.
- Be cautious with combined fertiliser-and-herbicide products; read our weed and feed guide before you buy one.
- For selective products, compare the details in our guides to Bow and Arrow weed killer and Spartan herbicide, but check the label first.
- In NSW, anyone who sprays weeds for fee or reward needs an EPA ground applicator licence, although routine garden and lawn maintenance falls under an amenity horticulture exemption.
How to get rid of onion grass
Onion grass is usually Romulea, or sometimes onion weed under another name. Winter lawns in western Sydney show it first, especially in thin, compacted turf.
- Confirm the plant using the table above before you choose a method.
- Dig small patches out with the corms, and bin the clumps rather than composting them.
- Thicken the lawn with good mowing, feeding and watering so weeds have less room.
- Check labels for Romulea, because a product for one weed may not list the other.
- Learn to spot other lawn weeds such as bindii and pennywort, which need different treatments.
- Repeat treatment next season, since corms and seed can stay dormant in the soil.
Stop onion weed coming back
| Season | Job | Notes |
|---|---|---|
| Autumn (Mar–May) | Spot-check and dig new shoots | Small plants are easiest to lift with their bulbs |
| Winter (Jun–Aug) | Remove before flowering | Winter grass seeding through lawns in August gets mistaken for it, so check the plant |
| Spring (Sep–Nov) | Treat before seed sets; feed the lawn | Don’t let flowers form seed capsules |
| Summer (Dec–Feb) | Mow regularly and water deeply | Water within Water Wise times before 10 am or after 4 pm |
Onion weed removal cost in Sydney
Prices include GST and are Sydney metro rates for October 2026.
| Service | Low | Typical | High |
|---|---|---|---|
| Weed removal (per hour) | $57 | $75 | $105 |
| Gardener (per hour) | $52 | $75 | $115 |
| Garden clean-up, half day | $170 | $290 | $460 |
| Mowing, medium lawn (per visit) | $65 | $100 | $150 |
Common mistakes to avoid
- Pulling the leaves and leaving the bulbs, which regrow quickly.
- Composting clumps, which spreads bulblets around the garden.
- Using a non-selective product on the lawn and killing the grass around the weed.
- Using vinegar, salt or bleach as safer options; they are non-selective, and salt and bleach harm soil long term.
- Waiting until after seeding, when the next generation is already in the soil.
- Leaving bare patches after removal, which invites new weeds.
FAQ: onion weed questions
How do you get rid of onion weed?
Dig out each clump with its bulbs after watering the soil, bag the plants and keep checking for regrowth. For large areas, use a registered herbicide that lists this weed and suits your lawn, following the label. Act before flowering in late winter to spring.
What kills onion weed?
Digging out the whole plant with its bulbs works, as do registered herbicides with this weed on the label. Mowing, vinegar and boiling water usually kill only the leaves, and salt or bleach harm soil. Check the label and your lawn type first.
How do you get rid of onion grass?
First confirm whether it is onion grass (Romulea) or onion weed. Dig small patches with the corms, thicken the lawn and use a registered product that lists the weed and your lawn type. Treat before seed sets, and repeat next season.
How do you get rid of onion weed in a lawn?
Lift small clumps with a trowel and remove the bulbs, then patch the bare spot. For widespread infestations, choose a lawn-safe herbicide whose label lists the weed and your grass species. Keep the lawn thick with regular mowing, feeding and watering.
Tired of fighting weeds on your own? Our common lawn weeds guide covers more of the usual suspects. We maintain and treat lawns across Sydney, so book lawn mowing and weed control in Sydney and get a free itemised quote.
