From time to time customers ask about tunnel maintenance in the winter when it is not being used for growing.  This is a great question and the short answer is "it depends on your location and how much you want to work."  Let's explain...

LEAVING THE TUNNEL UP

There are several reasons why leaving a growing tunnel up for the winter could be to your advantage.  The main reason has to do with weather.  If you live in an area that receives a significant amount of snow then leaving your tunnel up allows you to keep the ground relatively prepared for spring seeding and/or planting.  Covered ground is usually not too wet and muddy in spring, requiring less work for  planting.  Because of the shape of the tunnel (usually quonset, rounded) snow does not usually build up excessively since it slides to either side.  If you do leave your growing tunnel up for the winter you also need to winterize the water lines by disconnecting the water source and opening the ends of your irrigation lines to prevent the water from freezing and cracking your lines.  Disconnecting a flush valve, filter and/ or any electronics (like a timer) and storing them inside would also be beneficial to prolong their life.  On the other hand, of you live in a warmer climate that gets little to no snow leaving your tunnel up may work perfectly into your growing strategy as well as not require much extra work.

TAKING YOUR TUNNEL DOWN

If you decide to take your tunnel down for the winter you will incur a little more work, but it may be to your advantage.  The biggest reason to take your plastic off and winterize your water lines would be to prolong the life of your plastic.  By taking the plastic down and storing it inside you remove the weather factor (especially the sun) from deteriorating the plastic and add life to it.  It may be possible to add several more growing seasons by removing the plastic, winterizing the watering lines and storing the flush valve, filter and any electronics.

The down side to removing the plastic, besides the work, would be the shape of the ground when planting season returns.  Again, if you live in a place of significant snow your tunnel may be full of snow in April or even May when you might be ready to plant your cool weather vegetables.  Instead of being covered all winter and ready to plant in spring you now need to clear the snow from your beds which will cause a muddy mess, let it dry and then prepare your beds for planting.  On the other hand, if you live in a warmer climate that does not receive much, if any, snow taking your tunnel down might be a great way to preserve your plastic and increase your investment.

At the end of the day either decision is fine and depends on the amount of work you want to do and the place where you live.  Whether you take your tunnel down or leave it up it would still be good practice to clear your water lines and store any valves, filters or electronics.  Those are relatively easy to detach and reattach when ready.  Happy growing!

See also this video from Curtis Stone from Canada and the amount of snow he sees.