Posted: 04/01/2015 at 13:32
It is Allium vineale which is a prolific weed in many parts of Britain. While doing my Certificate in Biology at the University of Bristol I wrote my thesis on it. I had my children help me with the statistics and we found from one plant you can get over 300 new live plants (it exhibits vivipary which means new plants from from the seedheads) plus 12 to 20 new bulbs from the bulb in one season. I tried all ways to eradicate it including different weedkillers, vinegar, hot water, digging it up and trying to find all the little bulbs but the only method i found that did eventually work was to scalp it and the grass round it if in the lawn. Very close mowing is the answer. It needs some green stem to survive so do not let it have any. As for allium triquetrum you have this if the flower stem is triangular. Not quite as invasive as vineale but pretty bad.