How many hours of artificial daylight for onion seedlings?

landscraper82(4a - ND)December 14, 2012

Sorry for the extra long subject heading...didn't really know how else to type it. So anyhoo, here's my problem. I have grown onions succesfully for a long time, but this year I sorta want to try my hand at starting my own seeds indoors. From reading a lot of other posts, I know to start them fairly soon, maybe in a couple of weeks.

My question is this, being in a long day onion growing area, if I give them too much artificial light while growing indoors, will this screw them up? Is it possible to give a seedling too much light? Any thoughts would be greatly appreciated!

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Mark(Oregon, Zone 8)

I've been growing onions from seed for 16 years now, but as i'm in Western Oregon my climate is very different from yours.
That said, you still may be jumping the gun quite a bit. I start seeding in flats the first of Feb. and transplant to the field 2 months later. I see no reason to start them sooner as the weather is unpredictable and as they finish by mid summer with no problem, why bother?

The other benefit of starting them in Feb. is my response to your actual question. I don't need lights. I germinate in the greenhouse (unheated) with a heat mat. Once they're up, they come off the mat and they do just fine.

Now that i've rambled on, i'm sure someone here can offer more info than me on starting onions under lights. Personally i'd be hesitant to do it as onions are light sensitive and i've heard of folks causing them to bolt prematurely because of the lights.


    Bookmark   December 14, 2012 at 8:07PM
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I do not have 16 years in, not by a long shot. I'm in Central Indiana (am I now in zone 6?). When I buy onions started locally in the first half of April, they are always very small. I am guessing they were started around first of March, which is too late in my book.

Last year, I started seeds in Mid-January. When seeds sprouted, I keep them under lights for at least 14 hours, maybe 16 hours. It does not confuse long day onions. The light is not intense and they need all they can get, IMO.

Later, I put them in an unused aquarium outside for green house when the weather was nice & sunny. Planted out in first half of March. We had a very mild winter. They were much bigger than the locally grown ones I usually purchase. This year I will try to hold off until February to start seeds. And I will start all my onions, but no later February 1st for me! We'll see how that works.

    Bookmark   December 15, 2012 at 7:10AM
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I've seen a warning against too much light for onion seedlings for the reason you cite. I's suspicious of that. it's not like tiny seedlings are likely to start bulbing. On the other hand, i see no great advantage to giving the seedlings fourteen hours per day of light - it just wasted electricity.

    Bookmark   December 22, 2012 at 12:07AM
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