Sweet onions are sometimes short day, meant to be grown over the winter in the south, and begin bulbing when the days lenghten past a certain number of hours. The length of a day depends on your longitude. In MY zone nine onions sometimes bolt (or flower) before they start to bulb, because it gets a little too cold in the winter, or they are meant for the north and the daylength isn't long enough. I'd cut off the seed head, and consider using them as green onions if all else fails.

Indeed, your onions are probably "toast" by now. Those flower stalks should have been pinched off as soon as they appeared. From that day on, every bit of energy went into producing that stalk and the blossom. So much so that any bulb which was being formed was also consumed. In the end, you get nothing for your efforts.

Next year, use your set onions only for scallions. Buy plants instead and avoid that problem.

Martin

Thanks Nanelle and Martin:

I don't really understand what happened. These onion sets were supposed to turn into a nice 3-4 inch bulb. What will happen if I just cut off any flower stalks that form ?

Wayne, as you know, onions are biennial. They bloom the second year. When you plant sets, you are planting them in what they think is their second year. Then they will rush to seed if they are too large to start with. You set them back a year by breaking off that flower stalk as soon as it appears. Used to be that one considered any set larger than a dime to be too big for bulb purposes. One sorted them out and planted the small ones in one row and larger ones in another. The larger ones were used for quick scallions. What I've now seen happening is that the sets are becoming larger and larger. This coincides with availability of plants almost everywhere. Now, if one wants bulbs, one plants plants. If one wants scallions, one plants sets. The problem is that it's going to take a few generations to get used to that since onion sets traditionally have never come with instructions.

Martin

Your good Martin...how did you know he used sets versus seeds?

I see it now..I planted these sweet onion (large round ones, when mature) sets in October 2004.

Wayne, for a quick but pretty good education on growing onions do a search for Dixondale Farms. They have a lot of good info on their site.

Thanks everyone