Answer: Onion (Allium amplectens) is difficult to eradicate because even if the tops are killed back, stored energy from the bulb allows new foliage to emerge. Herbicides available to homeowners are ineffective against onion, so the only sure way of getting rid of the weedy plant is to dig it up, bulb and all. It might be possible to starve the roots out if you consistently hoe down any new foliage just as it sprouts. Best wishes with your project!
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