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You’ve spent all spring and summer tending your garden. Its bounty has overflowed, providing you with fresh vegetables. Heading into winter, you may want to continue enjoying the fruits of your labors. Overwintering vegetables can be hugely rewarding; in some ways even more so than your regular sunshine garden. After all, most people give up on gardening without access to a greenhouse. You can overwinter vegetables and enjoy some of them all winter long. Do it all while getting a head start for the spring.
Choosing to Overwinter Vegetables
The first thing to decide is whether you actually want to worry about harvesting vegetables on cold, winter days. Or, would you rather just have fresh lettuce, peas, and other cool-weather veggies as soon as possible in the spring? You can certainly do both when you overwinter vegetables.
If you plan to re-plant crops and harvest over the winter there are some steps that you have to take. The first, and most key, step is to discover when your Persephone Period sets in.
The Persephone period is the time at which daylight falls below 10 hours in a day.
Depending on where you live, this may never be a problem! However, people growing vegetables in northern climates are all too familiar with days less than 10 hours long.
Seeds must be germinated and plants will need to have reached their fruiting stage before days are less than 10 hours long if you want them to produce harvestable fruits over the winter. The 10 hour days give them enough sunlight to create useable food. It also keeps the soil warm enough that the seeds will germinate. If you plan to let them settle overwinter in the ground and harvest in spring they will need to be 75% grown before the Persephone Period kicks in.
Best Overwintering Crops
Common overwintering crops include cabbage, brussels sprouts, peas, broccoli, cauliflower, carrots, lettuce, chard, beets, and spinach. Pick varieties that are known for being cold-hardy. Read information from seed sellers and reviews from people who buy and plant them. If you live in a particularly cold area look for seeds that are sold from growers in your region. These are most likely to be successful even when you ask them to work a little harder than usual. You want tried and true varieties when you overwinter vegetables.
For root vegetables, you want to avoid things like potatoes. They are full of water and will split, then rot, in a freeze. Instead focus on hearty roots such as beets, carrots, parsnips, and turnips. Parsnips can be pulled throughout the winter. Carrots, beets, and turnips will sweeten after they have frozen. You will want to mark where these are planted as their tops will freeze and fall off even though the roots will still be excellent to eat. Dig them up as needed but be sure to harvest all by the time you’re ready to plant again in the spring.
Overwinter Vegetables without a Greenhouse
You can extend the harvesting and growing season with a cold frame. In fact, some people have had so much success with cold frames that they’ve been able to successfully harvest all the way through the snow into spring! Remember, however, that you will have to brush the snow off your cold frame if it gets covered. This is so the sun can get to the frame to heat it and to prevent a build-up of moisture from the air not being able to circulate. You will also want to make sure that the lid of your cold frame can be propped up. This helps to circulate air if it gets too hot.
Another great method of overwintering vegetable crops is to cover them with mulch. Apply 4 or more inches of mulch and then cover with row covers or “mini hoop tunnels”. When you’re ready to harvest you can just pull the covers back, take what you need, and then replace the covers again.
There are lots of different ways to create a ‘greenhouse’ or cold-frame without spending a lot of money. From a simple wood box with a reclaimed window to reused plastic milk cartons, and even old buckets or clear trash bags. The most important things are that sunlight be able to shine through to the plants and that you be able to provide some air circulation.
Overwinter Vegetables to Harvest In Spring
There are a lot of ‘first of the season’ options that you can plant that will pop in the early spring even before the last frost. Plant in the fall before the Persephone Period beets, carrots, kale, spinach, scallions, sorrel, claytonia, and chard. When given a bit of a frost, chard loses much bitterness. Other popular autumn plantings are oriental salad blends that include mustard greens and bok choy (oriental greens are frosty hardy and can tolerate freezing).
Many gardeners also take the time to plant their favorite fragrant roots in the autumn for the spring harvest. Garlic, spring cabbage, broad beans (also known as fava beans), kohlrabi, and onions can all be planted in autumn for a first harvest in early spring, then replanted again for a fall harvest.
Watering in Winter
Perhaps the greatest challenge to overwintering your vegetables is watering. Too much water is bad. It will cause plants to rot long before a frost ever gets a chance to freeze them. Water once a week in October, every other week in November, no more than twice a month in December and January. Once the harshest parts of winter are over you can go back to every other week in February, and once a week in March especially if it’s warm.