For what to grow in your tunnel I can recommend "Growing Under Plastic" by Bernard Salt. Excellent book.

Even here I find the tunnel gets very hot, but it also cools down pretty quick at night. I keep the doors open all the time, with a mesh cover, but did close them last night as it got pretty cold.

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Aerodynamically the bumblebee shouldn't be able to fly, but the bumblebee doesn't know that so it goes on flying anyway.
~ Mary Kay Ash