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Is a cold frame the same as green house?


By Sneesam

United Kingdom Gb

I bought a plastic cheap green house and it's stood in my back garden. Is it okay to use as a cold frame? Can i start using it now to grow some seeds? when can i start using it?

I love the idea of growing seeds (grasses mainly) and i assume they can start in a cold frame pretty




Hi Sneesam. Welcome to GoY.

Basically what you have there is a cold-frame with polythene, not glass or wood round it. It has got it's uses but please don't get carried away. Getting seeds to germinate (put out shoots if you are new to gardening) usually requires convincing them that it is Spring and Summer is just around the corner. I'm afraid your cold-frame/greenhouse (they are the same but a greenhouse you can walk into) will not be up to that task in the depths of winter. But all is not lost if you are patient. Generally speaking if you plant seeds outside (and if any 'experts' come in with 'cold stratification' I'll have a wobbler) they need the soil to warm up to germinate. That starts usually about the middle of April. If your cold frame is in a sunny spot it will give you a couple of weeks start. But there is a cheat. Start your seeds in trays in the house in late March. Once they have put out shoots, which will take a few weeks, transfer them to the cold-frame. The thin plastic will protect them from the worst of the weather that is yet to come, even the occasional hard frost. You can then plant them out in May when it is safe.

So don't be impatient (never works in gardening) and you can get a start of 5 or 6 weeks on straight planting out.


15 Dec, 2008


Hi John,
I certainly am not going to argue with that.
What does cold stratification mean? is it like selfed LOL.
Great to see you back on form.

15 Dec, 2008


Cold frames are not generally used in the uk for germinating seeds as they need heat to get them going.
The cold frame which you have is used for more mature plants that have germinated, been pricked out into a separate pot and are being weened into getting used to cooler temperatures. When you take soft and hard wood cuttings they are also usually put in a cold frame, just to keep them free of frost.

15 Dec, 2008


It would be a good idea to put a layer of polystyreen at the bottom of your coldframe to keep your pots and trays off the cold floor. I grew some Stipa tenuissima (Maiden Hair Grass) from seed last spring - grew really easily, so I'm sure you'd be fine with something like that - but as said above - don't be too impatient as you will have much to lose if there is a late 'cold snap'. Good luck :-)

15 Dec, 2008


as much as i hate to agree with John, lol he, and the others are quite right, i have a walk in cold frame/mini greenhouse, that is excellent for overwintering young plants, things that are a bit on the tenderside, ect but as i found out last year, not warm enough to start off seeds really early, certainly not this time of year. you can get a head start on them, but if we have snow for easter like we did last year, could be a nightmere. mine is in a really sunny possition, so i did find come late april, the things that i sowed in the coldframe were far bigger than what went straight into the bed, a few weeks later, so well worth having.

16 Dec, 2008


Oy Maj. Your name is on ze list. Lol.

16 Dec, 2008


lol oh no please don't arrest me!

16 Dec, 2008


One thing to consider. The "cheap coldframe" you bought might have one big problem. Too hot during the day and cold at night. I would position this on the east side of a building. Morning sun only. If you put this critter on the south (wondeful site for sun) you might get huge temperature differentials.

Most coldframes are made of wood with a glass or plastic cover. One that can be vented.This one will have to be played with. I would not put it on a S. or westerly setting, unless you frame the bottom with wood or something.

17 Dec, 2008


Sneesam, the previous post is nonsense. You will NOT get huge temperature differentials in April, or in the UK at any other time. East is the worst possible direction. If frost should get on your seedlings then the morning sun on them before they have defrosted naturally can cause more damage than anything. Just use your plastic cold frame as it was meant to be used. Preferably south or south-west facing. It wont have to be 'played with'.

Sorry if you are being fed misinformation which is NOT a usual thing on GoY. I don't think it will happen again.


17 Dec, 2008

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