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Onion weed or Asphodelus fistulosus, a perennial weed, can cause a few problems in lawns so it’s a great idea to learn how to treat this weed in your lawn.

What Is Onion Weed?

Asphodelus is from Greek meaning ‘head of a pike’ and refers to the appearance of some plants in the lily family. Fistulosus is from the Latin fistula meaning tube and refers to the hollow leaves.

Onion Weed refers to its weedy nature and leaves that resemble onion leaves. It does not have a bulb or smell like onion. It is an invasive plant with long, cylindrical leaves and white flowers.

How To Treat Onion Weed In Your Lawn

It can be fairly easy to eradicate onion weed from your lawn by ensuring your grass is growing vigorously – a healthy, thriving lawn will out-compete it in a relatively short period of time, with no other course of treatment required. Typically, having onion weed in your lawn is merely a sign that your lawn needs a bit more care.  

Because onion weed is a perennial weed, it stores nutrients and carbohydrates in its bulbs to generate growth in the following season, in the same way as spring bulbs such as daffodils. Trying to pull out or dig up these weeds in garden areas results in the parent bulbs releasing tiny bulbs (bulbils) from the base of the main bulb. These grow into mature plants, and all the digging has achieved is multiplication of the problem. To get rid of onion weed, you have to prevent the bulbs storing food for growth.

Pull the weeds out of the ground.

Hand pulling onion weed out of the ground is an easy, immediate option. If you’re looking for a natural way to get rid of onion weed, hand pulling is an effective method.

Use an herbicide.

Onion weed can be effectively and fairly safely eliminated by using an herbicide containing glyphosate. You should follow the directions given with the herbicide, but in most cases you simply spray the herbicide on the weeds you want to eliminate.

  • Always spray on a clear, non-windy and dry day.
  • Always wear protective gear when using an herbicide. 

Cover the area in plastic for a herbicide-free option.

Take a sheet of opaque black plastic that is large enough to cover the area infested with onion weed. Use several sheets if necessary. Hold the plastic in place with rocks or stakes, and leave it there for several weeks.

  • By cutting off light that the plants need to survive, this method will eventually kill the weeds.
  • This method will probably also dry out the soil in the area, and may kill grass or other plants along with the onion weed.
  • Plan it to take a year or so for the soil and area to return to normal.

Onion weed can also produce seed. Cutting off the foliage at ground level will prevent the plants making carbohydrates in their leaves, and also prevent seed forming.

This weed can be tricky to eradicate because the bulbils can be released whenever you disturb the soil. Cut off the foliage at ground level with shears to prevent it making food for the bulbs. You may have to cut back foliage several times as soon as it appears. If you do this consistently, bulb growth will become progressively weaker, and you will eliminate the problem without disturbing the soil and stimulating the growth of more bulbs.

Onion weed is more commonly found in undernourished soils, or where soil pH is unsuitable for healthy plant growth. Where onion weed has been a problem, check your soil pH, and improve organic matter content in soil to prevent the problem recurring.

For more lawn care tips, tricks and treatment contact the team at Daleys Turf. 

This Post Has 5 Comments

  1. A little confused about this info.. do i pull it out as suggested? Do i not pull it out because it will multiply with more bulbs. Also im reading thos article because it is about onion weed in my lawn but suggested that i might use herbicide which potentially kills my lawn too.

    I have just bought a house with around 80m2 of nice buffalo riddled with onion grass. Would love some specific guidance thanks .

    1. If you have a nice Sir Walter DNA certified lawn, then my advice is to fertilise your lawn, as onion weed generally only becomes a problem when there are bare patches or weak spots, a healthy lawn will keep most weeds out.

  2. For the best selective control of onion grass use Lynx herbicide ,or something similar with the same active ingredients,can be bought online ,it will take a while to kill it but it is the only way to go !

  3. Re onion weed in buffalo lawn. There appears to be no simple way of eradicating Onion weed / grass. ( long strappy leaves with in ground bulb and bulblets that fall away when plant disturbed and if left plant produces long stem with white flower virtually over night.) Will heat kill it? ie: Dig plant up with supporting soil in tact so as not to disturb bulblets. place plant and soil clump in foil baking dish in barbecue , use second baking dish as lid and run barbecue to virtually “cook ” soil and plant. Will this do the job once and for all ???

    1. Yes, that will kill onion weed, but also will kill everything else that is alive in your soil, years ago we used the ashes from the incinerator for soil amendment but it was useless, dead soil doesn’t grow much. You black plastic to do similar, its call soil solarisation, google that and have a read, it works

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