Here's the reply from the local Extension:


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Bottom line: in a greenhouse anything grows! Short days and cool temperatures slow all the growth processes and therefore production, but they still grow, albeit slower in a greenhouse!
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Since winter is a short day season any of the early cool season spring vegetables should thrive now.* Although early season crops are obviously accustomed to the shorter day length *of March/April you could easily alter this in the green house.* Green house growers extend the daylength by just dropping light bulbs directly over the crop for a few hours at sunset and a few hours at sunrise to simulate equal day/night length. **Honestly I am not so sure, unless *you are in commercial production, that *day length will be a factor of concern.* You might find that night temperatures are of *greater concern and the cool season crops listed below will again be the best choice crops if the green house drops into the 55 degree range at night.
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I have no hydroponic **experience in I don’t know what will perform best in water.
Cool Season Crops: *Lettuce is one we see frequently planted hydroponically. Other ideas: Brocc, Brus Sprouts, Cabbages, Cauliflower, Peas, Radishes, Spinach
See the attached planting lists and any plant that goes into outdoor soil before May 1st can be classified as a cool season crop. I have also seen swiss chard grown hydroponically and many of the herbs.
Hope this gives you some insight.
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If you have more questions we are here to help.
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Joyce Browning
Urban Horticulturist/ Master Gardener Coordinator
University of Maryland Extension