I let the onions flower just because I have way too many onion plants all over the place, so I don't care if it sets them back. The flowers look nice. I grow them in flower beds, too, people are always asking me what the interesting flower is. :-) The flowers can be pulled from their lump and make a cute and tasty mild onion flavored addition to salads. Onions are totally perennial in my part of WI, so every onion my mother or I planted her just comes back every year if not completely pulled out in the fall.

With garlic, it depends if you have softneck or hardneck. You can tell when the scape forms. I think on softneck they look like of like onion flowers, not sure. On hardneck garlic they form really cool pointy swooping things that look swanlike in their curve. I grow some garlic in a flower bed and let it form scapes because they are so cool looking. In the garden I am just about to remove them, was just reading up on the process here before I do it. Was probably supposed to do it sooner as soon as I noticed them forming.

Marcia

Well, This the first year we have grown Shallots. I cut off the scape when it formed a bud( just like with GARLIC)
I've pulled maybe a handful of shallots so far and they are the size they should be. Thisd would be a good experiment for next years crop.

we were given an onion-type vegetable that the local person called 'scapes'. However it's 'leaves' were more like those of a tulip, and the oblong bulbs had less of a 'bite' than one would expect from an onion. Not garlicky either. I wonder what we were eating.