[Noah'strolly]

I have a cold frame and an unheated greenhouse. How much frost protection do they offer? Would it be safe to stand tomatoes, aubergines, sweet corn and cucumbers out in them? The first three will be ok on my windowsils for a few more weeks but the cues are getting a bit big.

[iwantanallotment]

I'm no expert, but have had several toms & cucs in coldframe straight from greenhouse for over a week now with no probs. Expect they'd need extra protection if we get frosts, though?

[Noah'strolly]

Thanks, I might try a few cues in the greenhouse, see how they get on before putting the rest out - I have 13, they're marketmore but I was planning on growing them in the green house.

[Trillium]

I find them good for retaining daytime heat if it's sunny, but at night it gets quite cool inside, which is why a lot of folk insulate them with rigid polystyrene, and if the temperature drops to frost point you need to put a blanket or such over the frame for the night. My new coldrame will have a double walled 'greenhouse' top rather than single pane glass. Grannieannie has a doubleglazed coldframe which I believe is quite frost hardy.

[Noah'strolly]

I have a big wooden coldframe and a few plastic ones - How about I put a plastic one inside the greenhouse - double protection?

[Ivor Backache]

I had a similar problem. Buy a maximum/minimum thermometer and check the cold frame for a few days and see what the temperature really is at night. Most nights for me it is about 8 degrees so I have started moving plants into the cold frame. Still need to keep an eye on the weather forecast.

[paintedlady]

my cold frames are on my patio near the house so luckily frost is not so much a problem unless it is a really bad one (fingers crossed we won't get any of those now) but the patio flooring can get extremely cold which knocks the temperature down (especially at pot/root level).  A couple of weeks ago I retrieved a roll of floor insulation from a skip (like what you lay down for laminated flooring) and lined the bottom - amazing stuff 

[andtiggertoo]

Underlay an excellent idea, I was sure we had some of that in cellar, rushed down to see, couldn't find any but i did find a piece of roofing felt with a rough sandy side that is just right size for my old wooden coldframe, won't raise the floor temp in back yard much but think it will be good at deterring the slugs and snails. Result 

[Kristen]

I have a big wooden coldframe and a few plastic ones - How about I put a plastic one inside the greenhouse - double protection?

I have a little polythene grow-house that I put against the house wall in my cold conservatory that I use to bring my plants on, which works well and is several degrees warmer (at night) than the conservatory - which in turn is that much warmer than outside.  It hasn't fallen below 10C even on nights in late March where there was a sharp frost.

So I expect the same principle would apply for a cold frame in a cold greenhouse.  Some polystyrene sheet, or similar, insulation would probably help too.

[Noah'strolly]

Thanks everyone. I have put a few cues in my greenhouse under fleece (the plastic cold frame wouldn't go through the door and I didn't want to try taking it to bits incase the brittle plastic joints snapped) and will probably put some toms out this week.