Monday, October 26, 2015

Winter gardening: Low tunnels for the home garden

If you live in the northeast, then you've probably already put your garden to bed for the season. If, like me, you can't bear to say goodbye to the supply of fresh veggies you enjoyed all summer long, I'm here to tell you: it doesn't have to end!

There are lots of ways to extend your growing season if you live in a cold climate (we're in zone 5b or 6a, depending on who you ask). You can eke out a few extra weeks just by throwing a sheet over your crops when a light frost is predicted. You can keep some vegetables like carrots ready to harvest in the ground by covering them with a thick blanket of mulch. But if you really want to keep growing things like braising greens, salad greens, and herbs long into the winter, you're going to need either cold frames or low tunnels.

Cold frames are familiar territory for most people. We've been using them for years, but I've been increasingly frustrated with them. They are labor intensive to build compared to the amount of veggies they hold. Worse, they are finicky--if you don't judiciously open them on warmer sunny days, your veggies will overheat and fry. If you open the cold frame but don't remember to close it by day's end? Buh-bye winter garden.

This year, we decided to try out a different season extender; the low tunnel. Low tunnels look like miniature green houses. They are built out of some sort of flexible pipe (we used electrical conduit, or EMT) and covered with frost protecting row cover and/or greenhouse plastic. We built four 16' long low tunnels this year, at a cost of approximately $10/tunnel.

Building the tunnels

We closely followed instructions from Johnny's Selected Seeds, with one major difference; we didn't use the hoop bender they sell. Instead, we made a jig using a quarter sheet of plywood and a lot of screws arranged in the arc of the hoop, as shown in this Instructable.

How to grow in your low tunnels

Know when to plant

If you want to enjoy fresh salads in the dead of winter, you have to plan ahead. Plants stop growing once the hours of daylight drop below 10. These dark months are called Persephone Days, and you can find out when yours begin here: . For me, it's November 11th. You want to make sure your plants have reached harvesting size by this date; to do that, check your seed packets for "days til maturity" and count back from the beginning of your Persephone Days to determine the latest you can plant each crop.

Alternatively, you can take advantage of the warm soil underneath your low tunnels to plant very late for an earlier crop in the Spring. So, you could plant spinach at Thanksgiving and expect to be harvesting it a few weeks earlier than normal in the Spring.

Plant a lot

Since your plants won't be growing during the winter, you need to have more plants in the ground than you would during the summer, so you can keep harvesting even though the leaves won't replenish.

What to plant

What you plant will depend on your area, but here's what I've got in my winter garden this year: 
  • Cilantro
  • Onions (for greens)
  • Curly kale
  • Red Russian kale
  • Arugula
  • Spicy salad mix
  • Hakurei turnips
  • Carrots
  • Broccoli raab
  • Lettuce mix
  • Bok choi

Have a green winter!

Seeing those vibrant greens chugging merrily along in the middle of a long cold winter can really keep the winter blues at bay, and so can all the nutrients in that fresh food! Do you have a winter garden? What works well for you? What hasn't worked so well?

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