Night time temp in polytunnels - help

Polytunnels, cold frames, greenhouses, propagators & more. How to get the best out of yours...

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chicken4
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Joined: Tue Aug 05, 2008 2:21 pm
Location: Bristol

How much warmer than outside is my PT likely to be at night. It has a thermal cover, and it isn’t too exposed.
The night temps this week have been around 6 degrees

It’s a pain at the moment as in the day is really warm but I realise it takes a nose dive at night.
As the PT is on the plot, I can’t pop out in the early evening and cover everything with fleece
So should i just cover with fleece on the night with predicted frost, I’d have to do this at about 3pm in the afternoon.
Try to be organic, but finding it hard
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alan refail
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Location: Chwilog Gogledd Orllewin Cymru Northwest Wales
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Johnboy will be much more able to answer this than me.

As a general rule I assume that the temperature inside my polytunnel will be much the same as outside: i.e. if it's freezing outside it will, by morning, be freezing inside as well. The main benefit of tunnels is protection from wind and wet rather than cold.
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Johnboy
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Hi Alan,
There are many times when it is colder inside a tunnel than outside.
I have had plants frozen solid in their modules when the outside temperature has not reached freezing at any time during the night.
JB.
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Tigger
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I use a min/max thermometer to keep an eye on mine. I've got an 'inner sanctum' set up in one of them, made from a wooden frame and covered in bubble wrap which I keep frost free with a heater and then, once the tomatoe seedlings go in there, I set the heater to 10 degrees.
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