Help w/ expirement: Get onion to flower for seeds in 1 season

clones2February 29, 2012

So - my fun project for this year that I need help with is to grow some onions from seed (which were started last week indoors)... grow large enough to harvest, try to make them go dormant for 2-4 weeks, replant and get them to bolt to produce seeds.

Winters are long here, and I have trouble getting onions to overwinter for spring planting...strictly for producing seeds.

1) How large does my bulb have to be before I harvest?

2) I am guessing the quickest way to make this go dormant is a couple weeks in the fridge? Other ideas?

3) Is there a good way to "re-awaken" the onion to start the bolting process?

Last year, I was able to get some onions to bolt indoors in september... and they threw up 4-6 shoots over a couple month period...but never the big bolt with the seedhead.

I would love suggestions to grow a large enough onion and get it to bolt in the same year!

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LaurieK123(7b Oregon)

You might try planting them outside a few weeks early with mulch and a top covering; getting them warm... and then, while it is still cool (before real spring comes), remove the mulch and covering letting them get cold again. They should bolt when they get warmed up for the second time when your spring arrives.

Mine bolted last year. I mulched them in straw and was overwintering them for summer onions. February gave us 1-2 weeks of weather in the 50's - 60's; then it got real cold again til our real spring came. All, but 5 of my onions had huge, very pretty seed heads.

I would try at least a few different ways with groups of seedlings to widen your chance of success. One seed head will give way more seed than you get in a seed packet, so you don't need many to go to seed.

Laurie,

    Bookmark   March 3, 2012 at 2:38PM
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zeedman Zone 5 Wisconsin

An interesting experiment. I've noticed that some biennial vegetables run straight to seed, after the seed has spent a winter in frozen ground. Swiss chard & radishes have both volunteered in their old rows and done this, although I have yet to try winter sowing them intentionally for seed.

However... the conventional wisdom is that to save seed from root crops, you choose the largest roots (or bulbs) that do not bolt early. Any method which encourages early bolting runs the risk of selecting for that (undesirable) trait over time.

For seed saving purposes, it might be more effective to investigate better winter storage techniques, and get seed from those with the best storage life. That would be a trait worth encouraging.

If you could get an onion to reach full size & then break dormancy, that would overcome the negative issue of selecting for bolting. I'm not sure, though, that you would then have enough season remaining to get flowers & seed - if you can even get flowers. I've left onions in the ground past harvest time, and they sprout again in late summer; but leaves only, no flower stalk.

This is only my suspicion, since I have done no experimentation in that area... but I think that onion flowering, like bulb formation, may be triggered by day length. If that's the case, you may not be able to get onions to bloom in the shortening days of late summer. Certainly worth a try, though. You might be able to force flowering through shock, such as by root pruning, or slicing the sides of the largest bulbs. Keep us posted.

    Bookmark   March 4, 2012 at 3:54AM
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clones2

Will do - thanks for the suggestions. I did try to mulch a few onions and leave them in the ground overwinter, and I also tried to wrap a few in foil and keep them at 40 degrees in the fridge to see how well they overwinter. Others I kept indoors were kept too warm and only made it 2 months before sprouting... planted those in soil under a large grow light...but never got a seedhead... just several green shoots.

    Bookmark   March 5, 2012 at 10:40AM
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