I have onion weed growing among some of my favourite plants. It is also growing between my black mondo which I have between stepping stones leading to the porch. I've dug that area out and spread the weed. I've put down weed mat, reset the stepping stones and dug out the black mondo.
Now for the garden bed???? Ive mulched, the weed still is growing. Im reluctant to dig it out as I will kill my plants and probably just spread the weed more. The weed bulbs are deep and relentless.
Welcome to the Bunnings Workshop community @LovedaR. It's great to have you join us and many thanks for your question.
I don't often recommend Glyphosate but onion weed would be one of the exceptions. It's generally either a case of digging them out including their bulbs or poisoning them. Giving that it's notoriously hard to dig them out without leaving bulbs behind that easily break off I'd recommend a poison. To keep the use of poison to a minimum I would recommend using Yates 200ml Zero Weed Killer Super Concentrate 490 and applying it with a Yates Zero Weeding Herbicide Applicator Brush. This type of applicator is great, especially around other plants. It allows you to brush the product onto the onion weed without touching the surrounding plants.
Let me mention @mich1972 to see how she rids her garden of onion weed.
Onion Weed is a nightmare. We had it in our garden when we were in our old house. I tried everything from glyphosate painted on and diesel painted on and it would go yellow BUT still keep growing !!!!!!! It was dreadful. The only way to remove it properly is to dig out by hand. You MUST make sure you also remove the bulbets as they break drop onto the ground and start growing again. Remove put them in a plastic bag, put in the bin. Do not throw them in your compost. Good luck 😊
Welcome to the Bunnings Workshop community. We're really pleased to have you join us.
Great to see you receive some great advice so far for this very challenging and common weed. I would also recommend you check out this popular discussion - Best way to control weeds in the garden - as it contains fantastic advice by experienced members like @Adam_W and @robchin.
Please let me know if you ever need a hand getting the most from the site. We're here to help.
Good luck with your Onion weed problem. This will be a test of patience. The other comments given will all help. I agree that trying to dig them up might make them worse. I agree that trying to dig them up might make them worse.
The only way to control onion weed is to try and kill it in situ. Glyphosate will do the job but it will be more than a 1 time thing. It'll be a pain but you need to stop the food supply in the next season. So - kill the foliage, it will shoot again and then kill it again. Using a weed wand or a paint brush will allow you to plant around it. Never ever use diesel - it will stay in the soil forever.