greenhouse/coldframe question

Mon Feb 21, 2011 2:03 pm

ok, so lets say I have seedlings that are about 4 weeks old. (I normally put them in my greenhouse/coldframe during the day at this time but bring them in at night) can they survive below freezing temps at night in a greenhouse? they don't get frost on them because they're covered, but is it bad for the plants? I always wondered this and never could find the answer so I just always brought them in at night. is it the frost that kills the plants only? or is it also the cold temps? at what temp would you keep them in the greenhouse/coldframe?

Mon Feb 21, 2011 2:37 pm

I think it depends on the seedlings sheeshe.

Lettuce, cabbage, broccoli, mustard, spinach, etc. Early spring sowing seedlings, even some varieties of corn, can withstand frost and light freezing temps. (Actually lettuce is supposed to be able to take 20's)

Tomatoes, peppers, etc. cannot.

Mon Feb 21, 2011 3:06 pm

ok, that is what I figured... boo hiss. LOL!

so how can I make it warm enough in there to keep them in there overnight? bc it is such a pain to drag them in nightly. what temp do you think is the lowest a tomato could stand?

Mon Feb 21, 2011 3:27 pm

I have read about but haven't tried setting up incandescent lights in cold frames (I don't have one but am seriously thinking I want one

). Some say ordinary light bulb, some say Chick incubator. I use the tiny holiday lights under and around them in my unheated garage to keep them warm -- sometimes the temp in there have plummeted to 20's -- I wrap my entire seed starting set up with plastic on those coldest nights.

Tomatoes can take 40's and probably survive upper 30's, peppers are said to shut down in lower 50's and suffer growth set backs in 40's so put them closer to whatever heat source you use. they can survive the cold better if they have bottom heat --especially the peppers.

A second layer of floating row covers inside the cold frame would protect them better -- I'm sure you know about dressing in layers :wink:

Mon Feb 21, 2011 4:21 pm

lots to think about. hmmm. so lets say I built a new greenhouse/coldfram (cant decide how I want to build it yet) I could cover in layers and then run an extension cord out there and either plug in christmas lights or use my chicken lamp and put a bulb in there? and leave the peppers in the house I guess. at least it would be only one thing to take back in instead of 12. LOL!