How do you keep onions from bolting?
Then, should I cut the seed heads off my onions?
As soon as you see onions and shallots develop flower heads you should snip off the flower at the top of the stalk. Or if the stalk is quite thick, snip it all off about 1 inch (2.5cm) above the bulb but not the leaves. Doing this stops the plant from wasting energy on making seeds.
Furthermore, can you eat onions that have flowered?
Onions (Allium cepa) are biennial plants that grow in U.S. Department of Agriculture plant hardiness zones 5 through 10. A flowering onion crop is not ideal for a good onion harvest, but the blooms are edible, and you can still eat the onions even after they flower.
When the ground temperature goes above a certain temperature, this flips a switch in the plant to produce flowers and seeds very rapidly and to abandon leaf growth almost completely. Bolting is a survival mechanism in a plant. Some plants that are known for bolting are broccoli, cilantro, basil, cabbage and lettuce.