What an ingenious plant it is too! It ensures its survival by growing smaller bulbs, or bulbils, off the main bulb, which, when disturbed, break away to take up a new, vigorous life of their own, multiplying your onion weed problem in no time!
Lyn Bagnall writes about onion weed on her Aussie Organic Growing blog (she also has a book available on organic gardening) and has some ways to rid your garden of onion weed. Lyn says:
To get rid of onion weed, you have to prevent the bulbs storing food for growth. 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.
In an unused garden area, you can do this by slashing, or mowing, the foliage to ground level, then covering the area with black plastic for several months. Anchor the edges of the plastic with planks, bricks or whatever you have to prevent it blowing away.You might prefer to use mulch instead of plastic, esepcially if you are growing other plants and vegies nearby. Check the comments out on her post - some other ideas there too, like eating it! I'm not sure about that one, but you never know. :o)
|Onion weed by margoc|
In our raised garden beds, I use a small fork to loosen the soil and pull out the main plant very carefully, to minimise the lose of the bulbils - then I fish out as many of the small bulbs as I can see, though this is by no means foolproof. In larger, more sparse areas a spade would be better to catch as much soil around the bulb as you can, minimising disturbance. Some of the bulbs are really quite deep, often a spade head deep or more! And, as many forums and gardener comments say, even pulling out the green shoots helps, as it'll stop the bulb receiving sunlight (photosynthesis) and nutrients.
It looks like many gardeners face onion weed, as this amateur gardener shows!
All we can do is keep digging...!