[Yana]

I have read that if tomatoes are subjected to night time temp below 10c the crop is affected.
I am about to pot up my toms into 9cm pots and put them in an unheated greenhouse as I've run out of windowsills indoors and they need to move up a pot size. I've got fleece handy to cover them with if the temp does drop.
Would appreciate everyone's thoughts on this idea.

[mumofstig]

Toms do seem to manage, under fleece, with temps a little lower than 10C as long as it is only for a while.

But, that said I'm still getting some readings as low as 2C in my greenhouse overnight - I doubt they'd survive that, even with a fleece on 

It maybe worth spending a few pounds on a maximum/minimum greenhouse thermometer to find out what the temps are in yours, rather than lose your plants.

[Headgardener22]

Mine are in a mini greenhouse within the greenhouse and they seem to be fine at the moment.

[Yana]

I've got a max/min thermometer in the greenhouse so I need to pay attention to that. I've been relying on the soil thermometer in the greenhouse but silly me, the toms won't be in the soil will they!!

I like the idea of a greenhouse within a greenhouse. I've got the Wilko ones I could use them.
Thanks 

[3759allen]

i'm thinking something similar, think i'm going to take a chance and bing inside if we get a cold night.

most seem to say that below 5 degrees is a no no, thats what i'm going to go with and see what happens.

[mumofstig]

In the cold plants turn blue, they may not die, but will not recover to flower and fruit as well as plants not chilled.

Some good tomato info here (sorry you have to convert F to C  ) from Seed Savers Exchange.
http://forums.seedsavers.org/forum/gardening/vegetables-fruits-other-edibles/3447-minimum-temp-for-tomatoes

post #7

[Goosegirl]

I've got a max/min thermometer in the greenhouse so I need to pay attention to that. I've been relying on the soil thermometer in the greenhouse but silly me, the toms won't be in the soil will they!!

I like the idea of a greenhouse within a greenhouse. I've got the Wilko ones I could use them.
Thanks 

I have had one for a few years. Got it from a garden centre for about £18 and it has four shelves plus a quite thick transparent cover. I bought a cheap fleece mini-GH cover from Wilko's to go over the top and find that the max-min temp is about 3-55 degrees higher that in the GH itself. I also stood it on some insulating board so the cold doesn't strike up from the floor.

[Yana]

I've got a max/min thermometer in the greenhouse so I need to pay attention to that. I've been relying on the soil thermometer in the greenhouse but silly me, the toms won't be in the soil will they!!

I like the idea of a greenhouse within a greenhouse. I've got the Wilko ones I could use them.
Thanks 

I have had one for a few years. Got it from a garden centre for about £18 and it has four shelves plus a quite thick transparent cover. I bought a cheap fleece mini-GH cover from Wilko's to go over the top and find that the max-min temp is about 3-55 degrees higher that in the GH itself. I also stood it on some insulating board so the cold doesn't strike up from the floor.

I've got a piece of thick polystyrene so could use that to stand the greenhouse on.
I'm going to give it a go and if the temp looks to be dropping will bring them indoors

[JayG]

Don't expect too much from fleece alone - how much heat energy is stored is largely dependent on the mass of the item, and fleecing can only prevent some of it being lost.

Small pots of compost, for instance, don't store much heat, so don't have much to lose, and will quickly drop to near the ambient temperature overnight.

Mum's link clearly explains why avoiding temperatures lower than 10C (50F) for any length of time is a very good idea! 

[Annen]

In the cold plants turn blue, they may not die, but will not recover to flower and fruit as well as plants not chilled.

Some good tomato info here (sorry you have to convert F to C  ) from Seed Savers Exchange.
http://forums.seedsavers.org/forum/gardening/vegetables-fruits-other-edibles/3447-minimum-temp-for-tomatoes

post #7

Oh! That could be why my tomatoes didn't produce much last year! Mine went blue with cold, but they haven't this year I have brought them into the house every night, so I expect bumper crops.

[mumofstig]

but they haven't this year I have brought them into the house every night, so I expect bumper crops.

Sound plan 
I know it's a PITA every morning and evening, but I believe it is worth it!

[boddy]

Having read this post I've just brought mine into the house tonight from the greenhouse. They haven't got their first true leaves yet - I can just see them ready - do you think they'll be badly effected if I bring them in from now on? They're only tiny. Been out there about a week since they germinated in the airing cupboard.

[Steveharford]

Inside my plastic polytunnel/ greenhouse the temperature has been down to 2.2 deg without any apparent harm . I keep my toms within a mini greenhouse inside that for protection. ( see pic). But I have left one tomato plant outside that to see how it fares and so far there appears to be no difference. I wouldnt risk it with the rest of the plants though .

[pigguns]

Same here, under fleece, under a mini greenhouse inside the greenhouse..... always have a fit at least once in Spring on the morning I forget to ventilate, I'm at work, and it gets hot!

[Kristen]

I put a recording thermometer in a 4-shelf blow-away in my unheated greenhouse back in February.  It was no warmer in the blow-away (in fact it was colder, but that was probably because the thermometer was on the top shelf, whereas the one in the greenhouse was on a pot on the ground and probably benefited from some rising heat).  Either way, no temperature advantage / better insulation in the blowaway.

Even modest heat will do in a blowaway though - an incandescent bulb, or a Tea-light for example.