Hi Gerry, At least ten, maybe more years ago I planted some alliums in a bed in my garden. A year or so later I decided to get rid of them. However they will not go away and have spread all over the garden. Every year since then, at this time of the year I remove hundreds of them, being very careful to remove the little bulbs as well, and am always always on the lookout for any bulbs I might have left behind Is there anything I can do to get rid of them once and for all? Many thanks Regards Kay
However, if you keep it up, these too will eventually be exhausted but do not allow the plants to self-sow again.
As an alternative to removal, you can wipe the foliage with Roundup from a damp sponge using gloves. Avoid drips onto desirable plants.