How would you like it if you could go out to your garden on a snowy, winter afternoon and pick some fresh lettuce for your supper? Well, you can! And very easily too! No need for constructing a detailed cold frame or expensive greenhouse. With some wire, plastic and string, you can build a simple garden tunnel to keep those cool weather loving crops thriving all winter long.
Here is some happy little Cos lettuce in my tunnel. This was after a few below-freezing nights, including one that got down to 15º! I have found that the Cos (romaine), and Bib or Butter-crunch varieties are better for winter gardens. The leaf lettuce like Black-seed Simpson, seem to get a bit frozen when the temperature dips really low.
So here is how I built my Garden Tunnel:
First you need to acquire some heavy duty wire. I got a roll of "9 gauge" at the hardware store. That is a good gauge. You definitely don't want it any smaller, but bigger would be great too. It has to be soft enough for you to curve it into shape, but not too soft. Make sense? :-)
I have raised beds, about 2 1/2 feet wide, so I cut my hoops 5' long. That makes a nice height for things like lettuce and baby beets or smaller chard. If you were just growing lettuce and spinach, you could make your hoops shorter. Push each end of the wire into the ground to form a hoop.
Now take some heavy string or baling twine and tie it to the center each hoop making it taut. This will keep the plastic from sagging in between hoops.
The plastic I got was a 10' x 25' 3.5 mil clear painters cover in the hardware store and cut it in half legth-wise so I had enough to cover two 20' tunnels.
Cut your plastic the length and width of your tunnel with extra for the ends.
Now at every other hoop, tie a length of twine to a garden staple (or piece of wire or old hanger bent into a "U" shape) and push it into the ground right beside the hoop. Pull the twine across and tunnel and tying it to another garden staple push that into the ground next to the hoop on that side. It should be just tight enough to keep the plastic taut. (hopefully you can understand what I mean by the pictures)
Make sure the ends are tied together securely. I use a "U" shaped wire pressed into the earth to hold it down.
Now you can slide up the plastic to give your plants some air on mild days and the strings keep it in place.
I cover my tunnel with old blankets if the temp is going to fall below freezing.
So there you have it! A simple, inexpensive garden season extender!
Unless you are covering already existing plants in the garden, I would recommend starting your lettuce and other plants inside and then hardening them off in an unheated garage or enclosed porch for a few days before moving them into the tunnel. While they do like the cooler temps to grow in, the soil might be too cold for them to actually germinate. Same things if you want to add new plants during the winter. Just start them in a milk carton or some such thing under lights. They will get the best start that way.