Harvest and consume the onions' bulbs as quickly as possible. Onions from plants that have flowered cannot be stored.
Let the flower grow to seed. Remove the blossom and collect the seeds, which you may plant the following season.
Cut the onion blossoms to incorporate into a floral arrangement. They pair well with bright flowers such as sunflowers and marigolds.
Eat the blossoms of green onions. They can garnish a salad, or you may fry them into golden brown fritters. Consumed Gourmet, a recipe and food photography website, provides an excellent recipe. You can also employ the blossoms as a fresh substitute for onion rings.