Farmer dave, I've got bad news for you.
When onions go for seed, they will not bulb properly.
You can do a couple of things:One; pull them and use them as green onion/scallion.
Number two: pinch off those buda as soon as you see them.
Even then, according to master FARMERDILLA, their onions will be small and not a keeper.
Last year some of mine bolted. I had no clue then as what to do.
most of those onions roted. When you cut them length wise you will see a brown layer in the middle.
That is where they start roting.
cyrus
If you choose to let them grow bulbs, use those first within 2 to 3 months first.

Dave - same thing is happening to me. This is about the fifth year we have grown onions and the first time we have had some of them start to go to flower. We snipped off the flowers/stem on some of them, "stepped" on some (recommendation from an old timer) and left some alone. It's an experiment to see which works better.

But I'm curious to know why this is occurring since it never had before. I wonder if it is because we had a short stretch of very warm weather(in the 80's) in April.

Hi Karen - I'm sort of doing the same. We pulled up the ones with the bigger buds - they were beautiful, about 1.5" in diameter and quite yummy. (Photos at my blog post below). Others I snipped the blossom buds, just to see what they'll do. Time will tell I guess...

Here is a link that might be useful: My 2010 Garden Blog

Onions are triggered to flower by cold when they are of sufficient size, ~3/8" and 5 leaves. Because of this you do not want to plant your onions too early. At the same time you want your onions to be as large as possible, so we tend to push the plant's growth near the danger zone. Set growers in particular raise them as large as they think they can get away with without bolting. If they bolted this year, you should try planting out the sets a few weeks later next year, or better yet use seed or transplants. A row cover early in the season can also keep them warmer, while also speeding growth.

This year I have about 400 onions of half a dozen varieties that I planted as seed in mid Oct (outdoors), and about 20 grown from sets planted in April. About half the set plants are bolting, but not a single seed produced plant has bolted. The plants from seed are larger as well. Based on that performance, I can't really see any redeeming virtue in onion sets.

Can you grow onions from the blooms?

Side thought... don't bother planting Walla Wallas unless you have volcanic soil. They will not be sweet.

I grew up on sets. My mother always got Stuttgarter, and had very few bolts. She planted as early as possible and as shallow as possible. Every summer we cured her onions right along with the potatoes in the empty north side of the corn crib. Her set grown onions stored until late winter/early spring. She always spring planted too, but that was zone 4; so not many winter hardy onions for that country.

I plant back whatever small Copras I get even though they are several times the size of sets and have not had a bolt in them in some years, but instead get them to grow on additional size. I have not had a bolting problem with any Stuttgarter sets myself.

I get an occasional bolt start in my fall planted multipliers. The sooner it is pinched out the less impact it has.

I do not store my onions cold nor refrigerate either the stored onions nor the sets. IMO they need a cold spell to initiate flowering very much like tulips do, which is one reason why fall planted onions more tend to bolt than do spring seeded or bunched plants. That also varies a whole lot by variety.

OldDutch, when do you plant back your small Copras? Soon after harvest in the fall or do you keep them inside overwinter and plant back in the spring? I had an Ailsa Craig split into lots of set sized mini onions this year. I have not planted them yet but plan to....just not sure when would be best.

hi ms nature,

I picked Copra because it keeps extremely well; so it will still be solid to plant early next spring. I do not expect that either Copra or Ailsa Craig would be hardy this far north; so I don't intend to plant my sets this fall. I would have some doubts that Ailsa Craig would keep long enough to get to next spring, but I know that Copra will, since I have done this before - replanting small Copra bulbs to grow on another year; I have not had a bolting problem from them yet either. You might have to plant the Ailsa Craig sets under lights, if they sprout too early which is actually quite likely. I would not expect them to winter over from a fall planting as far north as your and my gardens are, unless we have an exceptionally mild, snowy, and short winter.

The key is as early as you can work your garden and plant as shallow as possible. Here in Minneapolis, I have squirrels that bury peanuts and walnuts in newly dug earth; so I cover newly planted beds with chicken wire, until there is a good sprout, and the bed has settled.

I intend to also plant my multipliers next spring too. I know that works because that was done in my mother's garden, too, for decades.

Thanks for the advice OldDutch. It makes sense to me. I'll see what happens with my mini bulbs in storage and pot inside if needed. I'd like to get Ailsa Craigs that are somewhat near the size shown in seed catalogs some year. So far mine have been quite small. I have to use chicken wire when I plant in containers, but so far the squirrels leave the garden beds alone. Hope that continues.

I have a lot of topsets from my walking onions to get planted soon. They seem to handle any weather extremes or incorrect planting times with no problems.

My walking onions are coming out of dormancy now and all the walking bulbils are coming up all over that particular area. I have held the bulbils over until spring, too. You are certainly correct that very little bothers the walkers. About as dependable as one could ask for.

Special case for the local squirrels. A neighborhood pair of empty nesters hand feed the local squirrels, who are constantly looking for somewhere to bury the nuts. They have the little tree rats all named and they come right up and take the nuts out of their hands. Nice folks and its an otherwise more or less harmless hobby; so I take some minor precautions. Chicken wire is a relatively effective counter. I use 2' x 25' rolls (2 of them) that get moved around to where ever they are needed.