Endless Summer: How to Farm in Cold Weather

Think cabbage, carrots and beets, which can withstand light frosts (tomatoes are too sensitive) and consider planting winter vegetables in the summer. This advice varies according to region, but the most important thing is to figure out when the temperatures reach that magic threshold – the freezing point (32 degrees).

Rule #1: Choose very particular crops.

The types of plants that you put in the ground late in summer determine a lot about how extensively you’ll be eating those veggies throughout winter. You’ll want to consider how long it will take plants to reach maturity, what their light requirements are and whether they can withstand the cold. Frost is a vegetable garden’s biggest enemy. The first frost will finish off summer crops like peppers, tomatoes, beans and basil, which have no tolerance for below-freezing temperatures.

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– Carrots and beets can handle light frosts but need to be harvested before the ground gets hard. Both crops grow sweeter in cooler temperatures although their crispness can be compromised if left in the ground too long. Fortunately, both carrots and beets can be harvested and stored in a cool moist place (about 55 degrees) like a basement or cold cellar.

ÂŸÂŸ- Parsnips, spinach, cabbage, broccoli, kale and cauliflower are great for late season harvests. They don’t mind cold weather and perform well in low-light environments.

– When choosing varieties to grow for this late harvest, search for those with good storage qualities like winter squash.

Rule #2: Timing is everything when it comes to plants (and life).

Planting at the right time can vastly improve longevity. When planting crops for late-season harvest, start early so plants can properly mature. The best planting schedule?

– Kale, cabbage, cauliflower and broccoli planted in July (no later than mid-July) will mature sufficiently for October to December harvests, although different varieties of each crop may ripen at different rates. Cold temperatures stall growth.

– Plant carrots and beets no later than the beginning of August to ensure they mature to their desired sizes.

– Plant parsnips, Brussels sprouts and celery root earlier in the season (March through May) to assure their size before they are harvested late in the fall or winter.

– Spinach, lettuces, mache and mustard greens can be planted through September without needing protection from cool temperatures.

– Spinach and mache greens can be seeded well into October and will mature sufficiently throughout the winter in most parts of the country.

– Fall plantings of spinach and hardy mustard greens like broccoli raab will grow slowly all winter, making for a great spring treat. Parsnips planted in March can be harvested as late as the following March. Some hardy carrot varieties (labeled and sold as such) can be planted in September and throughout winter for maturation in April. Spring onions can be seeded in late fall or even frostseeded in winter for an early crop.

– Wherever you are, the key is to know when frost arrives. If you get light frosts, you can keep beets and carrots all winter long so that they mature in fall and are ready to harvest in winter.

– Follow a lunar planting calendar to coordinate plantings and harvests. Planting before full and new moon dates throughout the growing season. In upstate New York, for example, first frost occurs between mid-October and early November (also relative to the lunar phase), so we plan accordingly.

Rule #3: Protect your plants.

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