Update: Now some of the bunches are sprouting small flowers.

This is information that I found on the Seed Savers Exchange. this group promotes saving heirloom seeds. They give instructions for onions. If heirloom seeds can be propagated then so can wild plants.

Here is there instructions:

Onion - Planting: Start seedlings indoors 4-6 weeks before transplanting. Sow seeds in flats ¼" deep and spaced 1" in all directions. Transplant as soon as the soil can be worked in the spring.
Seed Saving: Biennial. Onions cross-pollinate and should be isolated by 1 mile from other onions going to seed. Select only the best bulbs for seed. Bulbs store 3-6 months at 32-45° F. Plant out bulbs in early spring and allow them to form seed heads. When the heads start to dry, cut off, dry further and thresh.

Here is a link that might be useful: Seed Savers Exchange