Grow An Overwintered Garden With These Crops

Spring and summer don’t have to be the only seasons for your garden. Overwinter these crops and enjoy home harvests well into the cold months.

by Leah Smith
PHOTO: all photos by Leah Smith

The summer garden receives a lot of attention. However, with just a little planning and care, your plot of land can provide you with more food as well as food that is exceptionally delicious.

Those who have tasted carrots, spinach or brassicas touched by the sweetening hand of cold temperatures can attest. It’s simply a matter of knowing what to plant when and how.

Slowed Down & Different

Managing an overwintering garden is different from a summer garden. Due to low temperature and sunlight levels, weed and insect pressures are either nonexistent or greatly reduced. These same elements also mean less water evaporation. Moisture will stay in the ground, so you won’t need to water frequently either.

However, these conditions could also lead to mold or mildew issues. Watch out for signs of fungus.

The vegetables in an overwintering garden (let’s say beginning in October and through March) will reach different stages of maturity at different times depending on planting time and plant type. Think of cabbages, leeks and root crops (not potatoes but carrots, storage radishes, rutabagas, turnips, etc.) as being in a “root cellar,” so to speak.

They have done their growing and are simply out there waiting to be harvested, holding for months. 

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Lettuce, cutting greens, kale, salad radishes and scallions that have already reached a harvestable size can be picked immediately. But they’ll also continue their growth (albeit slowly due to dwindling daylight) and can be harvested over a period of time as well.

If these same crops have been recently planted/transplanted when cold weather arrives and aren’t yet mature, they’ll maintain themselves and resume noticeable growth after the turn of the calendar. They’ll provide your late-winter harvests of these crops.

Note that it’s desirable to have any crops that began the winter fully mature completely harvested by the end of February for two reasons: 

  1. Many crops, from carrots and leeks to spinach and lettuce, will be stimulated to go to seed or bolt by the increasing daylight hours and temperatures of the oncoming spring. Even if the plants have admirably survived the winter in excellent condition, they’ll soon lose their edibility. Make sure to harvest them before they do.
  2. It’s time to use the ground they were occupying for the next crops—the late winter/early spring seedings of lettuce, radishes and scallions.

Read more: Keep the garden growing this winter with a cold frame.

Providing Protection

Winter weather isn’t the same from one year to the next. The need to shelter your crops will vary.

In mild years, it could be wholly unnecessary. In other years, particularly cold weather may compel you to provide cover. Don’t worry. You won’t need complicated protection.

With root crops, it could be as simple as a little extra dirt pulled over their shoulders (depending on how long they are to stay in the ground). Or you could line up straw bales on either side of your leek row, with some loose pieces on top for cover. (See “Hot Beds & Cold Frames,” below, for more information on setups that protect from the cold.)

Different plants also tolerate different extremes of cold, sometimes dependent on variety. For example, cabbage and Brussels sprouts can stand out in the early snows without harm. Salad radishes and lettuce, however, will always benefit from at least a little protection. 

It’s also true that the healthier your crops are and the more carbohydrates/sugars they produce as part of their growth, the colder the temperatures they can withstand. Sugars are plant antifreeze! So provide soil fertility to enhance their survival.

And note that you can harvest several crops frozen, including scallions, leeks and spinach. After thawing, they maintain their quality and are still of great use. Additionally, mâche, kale and some lettuces can freeze through and thaw out in the field, apparently sufficiently undamaged and able to keep going.

We’ve already referred to many crops with a talent for surviving cold weather. So let’s take a closer look at some of the best candidates for the overwintering garden.

Brussels Sprouts: Holiday Favorite

Don’t miss the sweetening effect of the cold with Brussels sprouts. Harvest no sprouts prior to at least a couple of frosts. Though Igor is a green variety capable of withstanding harder freezes, those who desire sprouts into January may want to “see red.” 

The red sprout varieties Rubine and especially Redarling can maintain sprout quality for months with only modest protection. Brussels sprouts require many days to reach maturity. Start them early (in late spring or early summer) so they’ll reach full maturity as winter begins.

For a slightly different crop, try the unique, cold-hardy and trademarked Kalettes. They grow little florets where their sprouts should be!

Cabbage: Generous & Dependable

Though savoys (with their crinkly, toothsome, nutritious leaves) are the choicest cabbages when is comes to overwintering, green and red options also fair well (but require protection).

For a savoy, choose from January King, Deadon or Winterfurst. Dottenfelder Storage, European Storage and Storage No. 4 are good green options. Ruby Perfection and Mammoth Red Rock are the reds of choice.

Read more: Grow some cabbage, a smart crop to keep around.

Chinese Cabbage: A Little Something Different

Chinese cabbage is a nice, surprising addition to a winter menu.

Not really built for cold weather, all varieties are not created equal. But try Suzuko starting out. With protection, heads are viable through December.

Carrots: Digging for Gold

Sow several successions of carrots from late July to mid-August for an extended harvest. Ideally, you should grow them inside a structure (cold frame or greenhouse) and covered with straw or a row cover.

overwinter garden

This isn’t strictly to protect the crop, but rather to make harvesting easier. Try digging a carrot out of frozen ground and you’ll see the wisdom! Choose from varieties Snow Man (white-fleshed); Yellowstone (yellow); and Naval, Napoli and Merida (orange).

Greens (Kale, Lettuce & Spinach): Love Those Leaves!

The leaves of many different plants lend themselves well to winter production, whether they have been planted for late autumn/early winter harvesting or planted after the turn of the calendar for late winter and early spring.

If you prefer chicory, endive, escarole, radicchio or arugula, certainly give these varieties a place. 

Additionally, two greens of particular importance to the winter gardener (and ones you won’t want to miss) are mâche and claytonia. These winter annuals don’t hold through the coldest periods but grow through them amazingly well.

The most popular greens—kale, lettuce and spinach—call for layered protection and special variety selection. For frost-sweetened kale, the tender and mild Siberian types are perhaps the hardiest. (Improved Dwarf Siberian works especially well, thanks to its size.)

overwinter garden

However, many standout varieties exist amongst the other kale types. These include the curly Winterbor and Vates, and the flat-with-ruffles (and very hardy) Beedy’s Camden and Judy’s Kale. 

For lettuce, leaf lettuces tend to do well planted thickly and harvested at baby size. (Tango and Red Tinged Winter are favorites.) However, other options for heading-lettuce lovers include:

  • Romaines: Winter Density, Winter Wonderland and (red) Rouge d’Hiver
  • Butterheads: Winter Marvel and North Pole
  • Jack Ice (crisphead) 

I’ve also found that Gildenstern—a crisphead/mini-iceberg that makes no claims of overwintering successfully—did so very well and provided tasty mini-heads in March. And for spinach, Space, Tyee, Giant Winter and Winter Bloomsdale are the best winter-hardy varieties.

Leeks: Soup Staple

Blau Gruener Winter, Bleu de Solaize, Ifra and Siegfried Frost are some of the finest overwintering leeks.

Start these early in the spring, essentially at the same time as your summer-season leeks. They have slower growth and very good field-holding capacity, and so are not ready for harvesting until late autumn arrives. With rich flavor and nutrition, they make great additions to winter meals.

Pea Shoots: Surprise!

Do your ground and yourself a real favor with this selection. Gardeners typically grow Austrian Winter peas as a nitrogen-fixing cover crop. But they also offer a sweetly green, pea flavor.

Especially cold-hardy, these plants make a welcome addition to a salad or cooked dish such as a stir-fry. 

Normally sown in early spring where winters are cold, production as a protected food crop in these same areas requires planting in late summer. You can begin shoot harvesting once they reach 6 to
8 inches in height. 

Capable of surviving 10 degrees Fahrenheit handily, winter pea shoots require protection at colder temperatures with whatever combination of frost blankets, cold frames and/or protective mulch your weather dictates. 

Once temperatures reach 40 degrees and upward in the spring, you have several options for this great crop. You can either put it under in typical cover crop fashion or allow it to produce its small pink flowers as an aesthetically pleasing display and/or an early nectar source for bees. They will grow either trellised or sprawling.

Salad Radishes & Turnips: Riot of Roots

In addition to storage radishes and turnips, their small, tender counterparts can overwinter as well. Turnips Hakurei and Zuercher are excellent picked as minis (very small, tops and all) and at a standard salad size. Zuercher will also maintain its quality if left to grow to storage size. 

Though your average salad radish will bring in a crop (when well protected), watermelon/red-meat types are more winter-hardy. Sometimes classed as storage radishes, when pulled at 2 12-inch diameters they are tender and sweet for fresh eating.

Try Starburst, Beauty Heart or Chinese Red Meat—wonderfully attractive!

Scallions: Enlivening Allium

While some scallions lack patience, others will wait to be harvested.

overwinter garden

Varieties that excel at this, such as White Spear Bunching and Evergreen Hardy White, can be ready in two months and hold for four—quite a harvest window.

Sprouting Broccoli: A Real Treat

If you want broccoli that will survive winter and into early spring, make it purple and sprouting. Bonarda and Purple Sprouting can survive unprotected as temperatures go down to 20 degrees.

(Purple Sprouting is hardier still and can survive the teens as well.) 

You’ll need to provide protection through the colder periods. But the effort pays off when they resume growth and production in March and April.

Expanding productivity to more months of the year is like adding space to your vegetable garden. What will you do with more space? 

More Information

Hot Beds & Cold Frames

Crops require shelter from cold temperatures (and the wind) to different extents. This can be done with different means, from simple to complex. Systems can have more than one layer of protection, and some can generate their own heat.

To protect crops, you might use the following.

  • straw or (chopped) leaf mulch to cover, with or without bales as sides
  • old blankets or bed sheets to cover, held up with stakes
  • old windows to cover, letting in light to heat up the area on sunny days and held up with bales (i.e., a simply constructed cold frame)
  • hoop system with row cover 
  • low tunnel constructed of hoops and plastic sheeting, with or without frost blankets
  • cold frame constructed of wood
  • an unheated greenhouse
  • hot bed—a growing frame warmed by heat generated from decomposing organic matter, ranging from animal bedding/manure, leaves and forest waste to wool, seaweed and cotton clothing
  • low tunnel, cold frame or hot bed inside a greenhouse

Note: Any system that generates heat from decomposition or the sun will have to be monitored for overheating as well as for maintaining a sufficiently warm temperature. 

This article originally appeared in the July/August 2022 issue of Hobby Farms magazine.

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