The Q&A Archives: Starting seeds in a greenhouse

Question: I have a 6' tall greenhouse that is about 3' across and deep. I got it to start seedlings, but I keep getting beautiful seedlings, but instead of sprouting a second or third set of leaves, they get tall and spindly and flop over. Why can't I get more compact, leafy seedlings? I use the seed starter mixture and have used Miracle Grow potting soil, but both ended up the same way. I water daily as need, but I don't keep them wet and the greenhouse is in a sunny spot. I always had this problem when I started seeds indoors, so that's why I got the greenhouse. Grrrrrr
Any suggestions? Thanks for your help. You guys are great!

Answer: Although it would seem that seeds should germinate and grow beautifully under greenhouse conditions, the fact of the matter is that your seedlings need a source of artificial light until they've developed 3-4 sets of true leaves. The tall, spindly and then floppy growth you describe is a classic symptom of too little light. Set up a corner in your greenhouse where you can provide supplemental light to your seedlings. I use fluorescent shop lights (two tubes per unit) and hang them from chains so I can move them up as the seedlings grow. Keep the lights only 3-4 inches from the tops of the plants (moving as the plants grow), and keep the lights on 12-14 hours a day. Be sure to turn them off at night -seedlings need time to rest.

I think you'll find a world of difference in the quality of your seedlings with this simple step.

Best wishes with your greenhouse adventure!

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