Cold Frame question...

Hi folks,

I want to try a cold frame for the first time this year. I've seen different ways of making them or buying them, but I am going to use the PBS method of bales of hay with the window on top. It's cheap and I have all the supplies here. Here is the link if you want to see it: http://www.pbs.org/wgbh/victorygarden/knowhow/pp/coldframes.html

Anyway, here is my question. If you are trying to let the plants stay warm, why would you open the window to give them some air? Wouldn't that be too cold for them?

Thank you.

Megan

It depends on the day-to-day weather you're having. If it's cloudy & cold, you'd definitely keep it completely closed; but if it was sunny out, even if temps were cold, you still might have to crack the cold frame open. You'd be surprised how hot it can get inside there - enough to not just keep your seedlings warm, but possibly cook them! That's why it's a good idea to keep a thermometer inside.

In addition, it's always a good idea to get some air exchange in there once in awhile to help ward off fungus & other warm-air seedling diseases.

Oh okay, thank you, that makes so much sense. Good idea on a thermometer too.

Thanks again.

Megan

You're very welcome!! My husband bought me a little cold frame last year, & I was truly amazed at how darn hot it could get inside on sunny days - even when outdoor temps were really cold. A couple of times I think I cracked it open just in time before everything wilted on me - lol!!!

One other question, do you leave the plants out there 24/7 in the cold frame?

Thanks.

Megan

It depends on the plant. When it was still dropping down below freezing at night, I did bring in all my really warm-weather vegetables, like tomatoes/peppers/eggplants.

Okay, great thanks again because it is going to be for tomatoes.

Megan

Oh - something I else I did sometimes that really helped.

If the weather was going to be "iffy" - like maybe/maybe not dropping to below freezing - sometimes I'd just "tent" newspaper over the veggies in the closed cold frame, which provided extra temp protection.

But I wouldn't use that method if it was supposed to get reliably really cold.

*Edited to add - I used several thicknesses of newspaper, but not so many that it would bend the seedlings.

This message was edited Feb 17, 2006 1:31 PM

Breezy, Let me add that on 'Questionable' nights I sometimes drape an old bed sheet over the entire cold frame, to cover the glass with a few layers. Like a blanket.

Megan, Good link.

Andy P

Hello
i have a question if i may? i m new to the cold frame also, when i m ready to harden off my seedlings do i put them directly to the coldframe or gradually add them to the eliments one day at a time for 7-10 days, then put them in cold frame 24/7 while adjusting the cover for weather conditions?
thanks
sue

Sue, I put them directly into the cold frame from the indoors. If I expect a particularly cold night I bring them back indoors until things warm up again.
Yes, be sure to monitor the temp inside the cold frame, it can really heat up in the sun. The glass will usually keep plants from getting sun burn.
As the plants get closer to being planted in the garden I take them out and let them experience the open air, wind, sun etc.
Another note: I don't water the plants IN the cold frame. I take them out to water, then return them. I have a problem with slugs if I get the inside wet.
Andy P

The automatic vent openers (use paraffin which expands/contracts w/ temp) are a plant lifesaver. I wish they were less pricey (35-55 bucks) but once you cook the contents of the cold frame, they don't seem that bad!

It's always a challenge before going to work. Is it going to be sunny or cloudy. If it's cloudy now, will it clear up? When in doubt, open a bit.
Andy P