Polytunel net doors

[match]

We've finally got the doors on our new 14x15ft polytunnel at the weekend, and have been watching the temperatures inside rise and fall (nothing planted as yet!).

We were amazed that while the night-time temps were down to 3C, today with lots of sunshine, while the outside air temp was 13C the inside hit 38C! With this in mind we're just working out what our ventilation options are.

The tunnel has double sliding doors at each end, and we have the option to fit a net panel to some/all of the doors - the instructions suggest doing so for the summer months and going back to polythene for the winter.

So a couple of questions:

1. At what times of year do people switch from polythene to netted? Is there a nice easy guide, like 'after the first frosts' or 'when air temps hit XC'?

2. What's the best approach for managing temps in the winter months? Is it a case of keeping things shut up unless warm weather is forecast? Or opening doors during the day and closing at night? Or some other magical incantation?

Really looking forward to getting things growing!

[SarrissUK]

Wow, 38! Imagine how hot it'll be in there when it's 25C outside! (Well here's to hoping, anyway!)

Net doors is such a good idea! I'm hoping to build a poly myself over the next few months, and I think that will definitely be on the cards for me

[Grumpy Gardener]

It depends on what you're growing.
I've had only had lettuce in mine over winter and have had the top half of both doors covered with netting only all winter.
I found in my first season that condensation was a bigger problem than the cold.
Since leaving the top open to allow ventilation I've had far less problems.
I plant tomatoes and peppers out around the middle of April and put the top back in at night for a few weeks but always have them open in the daytime, once again to stop condensation.
John