If you're going for seeds, then let them flower and continue on to make seed. If you're trying for eating onions, I'd cut the stalks as soon as you can so that the plant can direct the energy to the bulb or pull and use them now. I'd leave the ones that don't have stalks in the ground in order to form the standard, large bulbs.

Usually, an onion will flower in its second season or when it's been exposed to a period of cold / stress that fools it into thinking it's the second season. It could also happen from planting sets that got too big prior to stopping hte first growth.

Thanx for the input. I will go and cut the blooms off and watch to see what happens. I still have a ton of seed so Im only in it for the veg.
Peace

They are already spend up a bloom? That's probably not a good thing. I suspect all of them will be flowering very soon. I have found that cutting off the bloom spike does nothing. When you pull them up you will probably find the bulb is hollow and you will have to eat whats left very quickly. They will not keep.

Good Luck

Go ahead and cut the blooms off and see what happens. I usually get a few that bolt every year. It's usually not a big problem. Did you plant sets or transplants. Transplants are less likley to bolt.

One thing I learned is when they do bolt I use them first because they just dont save or last.

Mine are flowering and are shallots. I can expect the same thing as posted above since they are shallots? And, if I don't plan to store and save them, when will I know they are ready.

The stalks are tall and green and I cut off the flowering heads.