This story is excerpted from a post on Modern Farmer opens in a new tab. Ilustration provided by MGMT Design.
Covering crops when temperatures dip is key. Maine, Canadian and Scandinavian farmers are the experts on this. There are a few ways to protect the crops from winter extremes. There are lots of prefab cold-frames available but reused and recycled materials are the most rewarding.
Old windows are the classic reused cold-frame material but they get very hot and are usually heavy. The more modern versions employ polycarbonate panels (hard plastic) paired with levers operated by a wax-filled cylinder: When the wax grows hot it expands, activating the lever and venting the cold house.
A great way to reuse old greenhouse plastic — sheets of durable polyethylene typically used for walling greenhouses — is to place it over ground crops. It should be supported by bent electrical tubing and anchored with stakes. The sheets fit well over a 3-foot bed and stand about 3 feet high. Tie the ends tightly to the stakes, providing tension to shield against rain and snow. Leave an opening for air to enter on both ends and weigh it down on the sides with boards, rocks or sandbags for added sturdiness. For less intense seasons or climates than the Northeast, crop fabric (Remay, Covertan or Agribon) works better than plastic for protecting from the wind while allowing the plants to breathe on warmer days.
Straw! Straw is great for keeping soil from getting excessively hard and cracked from the cold wind. It also helps hold water. It is valuable for crops like kale, cabbage, cauliflower and broccoli for this reason and can help prepare beds for early spring seedings. Straw mulch over garlic will protect the ground from cracking; it can do the same for onions. Even carrots can grow right through the straw. However, it’s not right for all crops. It can make it difficult to pick crops like parsnip and spinach and can rot spinach if it gets too wet.
Unheated greenhouses provide improved protection; here you can grow lettuce and carrots because you are keeping the ground from freezing.
Advisor: Jack Algiere, Four Season Farm Director at Stone Barns Center for Food and Agriculture opens in a new tab
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