onion seed failure

wolverine1012March 5, 2011

We planted three different kinds of onion: candy, patterson, and claret. All were planted in a type of peat based potting soil mix that we have used to start all our other seeds for years. They were started in some aluminum pans with a soil depth of about 3". Initially we had the pans in the basement where it was cooler, but were getting no germination. We moved them upstairs into the warmth and germination was pretty uniform.

Being concerned that they were maybe getting too much light, we moved them back downstairs on heat mats and under grow lights which are on about 10 hours a day. Today it appears that practically all have died.

Any thoughts as to what might have gone wrong? Luckily, we've still got some seed that we were going to direct seed as a test to see how much the advance germination helped us. I guess I could still buy more seed, but I'd like to figure out what went wrong if I can.

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jimster(z7a MA)

I am not certain what caused your plants to die but I can offer some suggestions based on my experience.

I doubt your plants were getting too much light. Full sun would not be too much.

I consider 14 hours per day to be minimum for seedlings under grow lights.

Onions need to be started in January or early February. I think it's too late to start seed for this year, except maybe for scallions.


    Bookmark   March 13, 2011 at 8:22PM
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Any other thoughts on this? I know it's too late to start again this year, but I'd like to make corrections for next year.

    Bookmark   March 31, 2011 at 6:39PM
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seysonn(8a WA/HZ 1)

Onions, being cold weather crops, need only moderate temperatures to germinate. I would say 65F. But once germinated and sprouted a bit, should be kept cooler than say,tomatoes, peppers etc. But they will need the light. I would say an unhited garage type of location would be good.
Once the seedlings are established, they can be planted in the garden AFTER HARDENNING THEM OFF. Obviously, if out side temperatures are very cold, they will not grow substantially but will survive frigit temperatures.

    Bookmark   April 1, 2011 at 6:02AM
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