Cool Season Gardening: Guide To Growing Winter Vegetables

By: Liz Baessler

Just because the days are getting shorter and temperatures are getting lower doesn’t mean you have to close down your garden. Even if you live in a climate with hard frosts and heavy snowfall, cool season gardening is a viable option, at least for a while. Keep reading to learn about cool weather crops and growing food through the cold season.

Winter Season Vegetables

Cool weather crops are, as a rule, leafy greens and roots. Vegetables that produce fruit, like tomatoes and squash, need lots of warmth and sunlight and are not really suited to cool season gardening.

Leaves such as spinach, arugula, chard, parsley, and Asian greens thrive in cooler temperatures and can often handle at least light frost. Lettuce is a little less cold hardy, but it tastes the best when grown in cool weather.

Kale handles the cold extremely well and can survive temperatures far below freezing. Brussels sprouts, cabbage, and broccoli are all also good cool weather crops.

Roots such as carrots, turnips, parsnips, and beets can survive freezing temperatures and actually vastly improve in taste when the plant concentrates more energy on root growth and builds up sugars for frost protection.

Cool Season Gardening Tips

Although many winter season vegetables can survive cold temperatures, cool season gardening is more effective if you take a few steps to keep the plants warm.

Simply putting down mulch or a floating row cover can raise the soil temperature by a few degrees. Building a cold frame over your cool weather crops is even more effective.

You can stretch transparent plastic over a structure of PVC pipe or, more easily, lay hay bales around the perimeter of your winter season vegetables and lay an old window across the top. Your biggest risk if you do this is actually building up too much heat. Open your cold frame up on sunny days to allow some cooler airflow.

A more expensive, but often worthwhile option, is the purchase of a greenhouse. Even in cold climates, you should be able to grow cool season crops all winter long.

If none of these appeal to you, consider growing vegetables indoors. Herbs are always handy in the kitchen, and small things like salad greens and radishes can be grown in window boxes.

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Read more about General Vegetable Garden Care

Winter Gardening Tips From Zone 3

What coverings/protections work best for you in your winter garden?

  • Mulch and leaves.
  • A cold frame, hay or nothing for the hardiest crops.
  • I use clean straw.
  • I use greenhouses with small heaters to keep the plants from freezing.

What other winter growing techniques work best for you to get the biggest, healthiest harvests?

  • Choose your crops depending on your area and typical weather. Plant in a place that isn’t accidentally going to get worked in the spring (which happened to me this year . oops).
  • I try sowing some things in fall so those crops can start early in spring at their own convenience.
  • I grow a lot in cold frames inside my greenhouse under my regular benches.
  • Spend as much time in your garden as you would in the summer.

What are your best tips for getting the timing right when planning and planting a winter garden?

  • Watch the weather forecast for snowfall and drops in temps.
  • Observe results of trial and error, and learn to count backward!
  • I start in the first week of November while there is still a bit more warmth and sunshine to give the plants a head start for the colder, darker months ahead.
  • As winter can and does start as early as the first killing frost in fall, I do not plant a winter garden. We only have June, July and August in which to grow a garden, and this year my last killing frost was in June. The killing frost last fall was in September.

A Winter Vegetable Garden in Northern California

  • The sweet rewards of winter gardening are worth the effort of stretching the season.
Cole crops such as cabbage and broccoli are the stars of the winter garden. A floating row cover can protect your winter crops from frost damage.

For years, I had a May to September relationship with my garden. I would plant in spring, harvest in summer and fall, and do nothing during the winter months but wait and plan for spring again. Last year I decided to keep my garden growing year-round. I was motivated by my love of broccoli, although I also wanted to grow other cool-weather crops that just couldn’t take the heat of the hot summer months: peas, spinach, cauliflower, and cabbage, as well as lettuce and other salad greens. I found that, given a good strategy, a winter garden is easier to manage than a summer garden, and I feasted on greens through the months when I usually long for the flavor of freshly harvested vegetables.

I am fortunate to garden in an area of northern California with an agreeable climate. Although we typically have several months of intense winter rains, it never snows, and only occasionally do we have a killing frost. The usual summer crops of corn, tomatoes, peppers, beans, squash, and melons would never grow during the winter, but many other vegetables thrive in the cool, even cold, weather of October to April. Granted, my climate makes it fairly easy to grow vegetables year-round. Without hot beds and hoop houses, winter gardening is impossible in areas where temperatures routinely drop below 25°F. But kitchen gardeners in other regions can enjoy a longer growing season even if the mercury dips to freezing levels. What it takes is a bit of planning and some useful season extenders, like floating row covers, cold frames, or small, plastic-covered hoop tunnels.

Planning ahead is key
Forethought is essential to getting your winter garden off to a good start. Even though many vegetables will mature and keep well during cold weather, most need warm soil temperatures to germinate and grow to a sufficient size before cold weather sets in. Of course, you can start seedlings indoors and nurture them there until they need to be hardened off and transplanted out. If you want to start some vegetables from seed to transplant later, sow your seeds in August, when soil and air temperatures are conducive to germination and strong growth. Be prepared to transplant by Labor Day, so your seedlings can take advantage of Indian summer’s mild weather.

There are no hard-and-fast rules for when specific crops should be planted, but, in general, the earlier the better. Optimally, seeds should be started in late summer, but nursery seedlings transplanted in early fall will still do well.

Some plants, such as onions, leeks, and cole crops, take a while to become established. Plant these early in August. Peas, carrots, beets, spinach, and lettuce can be direct-seeded and planted in succession for an extended harvest, but start planting in early August. Start peas, carrots, and beets between August 1 and 15 direct seed spinach around August 1.

Prepping the soil and setting up structures should be done before winter. In this case, the winter pea crop needed to be planted in the fall, when warmer soil conditions favored germination.

All of these dates are applicable to my gardening zone and will change depending on your zone and microclimate. It may make more sense to determine how many days until a crop can be harvested, then count back to estimate when to plant. For instance, carrots can be harvested approximately 60 days after planting. Count back from a November harvest to a late August sowing.

When choosing varieties, you can pick your favorites, as I did, with an eye to staggered harvest dates. Or, if you have colder temperatures than my region has, choose cold-tolerant or short-season varieties. In addition to determining when to start specific plants, you also need to have some of your garden beds emptied of the summer crops and the soil prepped and ready for the winter crops.

Getting off to a good start
I plant in established raised beds from which I’ve already harvested a summer crop, so I don’t have to do any more digging or tilling. My beds were previously double dug and well nourished with organic matter, so after removing the old vegetation, I just add a few inches of compost and other soil amendments as needed to supply the incoming plants with fresh nutrients. Planting year-round requires close attention to soil fertility, or your garden won’t flourish.

Get more info on growing cool-season vegetables:

• Spinach
• Mâche
• Beets
• Greens
• Cabbage
• Carrots
• Onions
• Kale

• Extending the Salad Season
• Cold Frame Gardening

I use aged compost, which has had time for excess salts that might harm crops to have leached out. My choice of amendment is mushroom compost, a medium used to grow mushrooms. It contains straw, horse manure, chicken manure, gypsum, peat moss, lime, molasses, and cottonseed meal, to which I sometimes add grape pumice and rice hulls.

If you don’t have raised beds, soil preparation is even more important, to create good drainage. Heavy winter rains make good drainage essential in my garden.

You’ll probably need much less space for your winter garden than for your summer garden, since winter vegetables are more compact than tomatoes, melons, and squash. I use three raised beds, approximately 4 feet by 20 feet each, along with a 20-foot row for snap peas and snow peas, which provides family and friends with ample produce all winter long. I recommend planting one bed in root crops (carrots, beets, and onions), another in cole crops (broccoli, cabbage, cauliflower, Brussels sprouts, and bok choy), and another in salad greens (lettuces, mesclun, spinach, and chard). I plant winter crops closer together to prevent erosion from hard winter rains.

Cole crops and greens are the stars of the winter garden. These crops grow to maturity in cool weather without bolting.

Plant at the right time

In climates such as the author’s, in northern California, lettuce seedlings can be planted throughout the winter, providing a staggered harvest.

Since most vegetables come in many varieties, with different maturation rates, you can plant your winter garden all at once and still be able to harvest over several months. For instance, plant 6 or 12 plants of three different kinds of broccoli and cabbage, with maturity dates of 60, 80, and 100 days. For beets, onions, and carrots, you can plant the same variety of each (preferably one suited for over-wintering) and harvest them at different stages of growth, as needed. Chard, spinach, lettuce, and salad greens are also suited for an extended harvest if you take just the outer leaves and let the plant continue to grow. Since lettuce and most greens tend to mature quickly and germinate well in cool temperatures—they are the exception to the rule that warm conditions are required for germination—you can sow or plant out new transplants every three or four weeks throughout the winter. However, since lettuce won’t bolt in cold weather, you might opt for the easy way: Plant everything at once, and be done with it.

Seeing the garden through
Maintaining my winter garden was remarkably easy. I had to water regularly during August, September, and October, but once temperatures cooled off and the winter rains came, I didn’t water at all. Weeds don’t grow fast in fall and winter most of my weeds were wild grasses, which I just cut short with grass clippers. It’s actually best not to pull weeds, because when the soil is soggy, you risk harming your vegetables’ root systems. And the roots of the weeds keep the soil in your raised beds from washing away.

Insects aren’t generally a problem in colder weather, and although snails and slugs can proliferate, I had enough vegetables planted in my garden to ensure there was plenty left over for me. All of my crops were hardy enough to withstand frost, except for my lettuces and salad greens. Whenever frost was forecast, I covered that bed with a floating row cover.

Through the winter, row covers keep cold-hardy crops alive during the winter, which is rainy and cool but not prohibitively cold.

In other parts of the country, weather may be capricious. Have floating row covers ready to protect plants from sudden freezes. Quick changes in temperature are more damaging to plants than gradual changes.

In retrospect, my winter garden took much less effort than my usual summer garden. Once planted, my vegetables seemed to grow well by themselves with little intervention. The major effort on my part was venturing out into the rain to harvest whatever I felt like eating or cooking. But it was well worth it: fresh steamed broccoli and cauliflower, homemade coleslaw, sweet garden peas, borscht made with my own cabbage, beets, and carrots, and of course, incomparable salads. If only I could grow tomatoes in winter to top them off.

For your own garden, you’ll want to seek local advice about the best cover crops or mixes for your area. Till or rake open areas and empty beds to about 2 inches deep, then broadcast the seed and rake in to cover. There’s no need to water if you plant just before the fall rains.

by James Kerr
October 2000
from issue #29

Monthly Vegetable Gardening Tips

  • January
  • February
  • March
  • April
  • May
  • June
  • July
  • August
  • September
  • October
  • November
  • December

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Think about seeds

Local nurseries carry a good selection of spring and summer vegetable seeds, but if you are looking for new or unusual vegetable varieties, or even the weird and wacky, catalogs or online stores will open up a whole universe of varieties to try.

When planning your garden, think about growing varieties that you cannot find at farmers markets or grocery stores.

Check out the Sacramento Vegetable Planting Schedule (PDF) (EHN 11) for a general planting timetable.

Plant bare root artichokes
You should be able to find bare root artichoke crowns in nurseries in January. If you want to give them a try, your best bet is to grow them in a location that gets morning sun and afternoon shade. They are grown commercially in the Monterey area, and they prefer a coastal climate. As a result, they tend to suffer in our summer heat, so growing them in an area of your garden that is protected from the afternoon sun will help keep them from stressing too much.

Artichokes are very large plants, so give them plenty of room (4 to 6 feet apart). They also make a great architectural statement, so think about planting one in your landscape. Do not be surprised if the plants slow down and go a bit dormant in summer. When the weather cools down in the fall, the plants should start growing again. Artichokes are heavy feeders, so fertilize them every month with a high nitrogen fertilizer.

Water artichokes regularly during the growing season. If they are grown only for ornamental value, artichokes are fairly drought tolerant however, they will go dormant in summer heat.

Buds are ready to harvest when they are tight and plump. Cut off buds with 1 to 2 inches of stem. The younger the bud, the more tender it will be. If the buds have gotten away from you and start to open, let them continue to flower. As a member of the thistle family, the large purple flowers are a show stopper and attract honey bees. Click thumbnails for a bigger view:

Harvest broccoli and cauliflower
If you planted broccoli or cauliflower last fall, you may be able to start harvesting this month.

Harvest broccoli while florets are tightly closed (before the flower buds open). The immature flower heads, parts of the attached small leaves, and a considerable portion of the stem (4 to 8 inches) are edible. Although you may be able to start your harvest this month, your plants may produce for several months because of production from side shoots between leaf or branch stems after the main one is removed. If temperatures get too high, broccoli will "bolt" into premature flower stalks that will bloom and go to seed. Store harvested broccoli in a plastic bag in the refrigerator. See additional information about broccoli (PDF) . Click thumbnails:

Most cauliflower varieties need about 2 months of cool weather to mature. When the flower heads (curds) of white-headed varieties are about the size of a chicken egg, blanch them by shading out sunlight to keep them white, tender, and mild flavored.

Harvest cauliflower when buds are still tight and unopened. With a sharp knife, cut off just below the head. If heads become over-mature, they tend to segment or spread apart and the surface becomes fuzzy. Use or preserve right away. The 'Snowball' variety may be grown as both fall and spring crops and can produce good heads within 2 months after transplanting. See additional information about growing cauliflower (PDF) .

Plant asparagus crowns this month
Asparagus is a perennial, cool-season vegetable, its long spears coming up year after year. So when you make the bed, do it carefully – your asparagus may be growing in it for 12 to 15 years or longer.

Asparagus grows from seed, but it is easier to buy 1- to 2-year-old crowns. The crowns are actually rhizomes (fleshy stems that store food for future plant growth--see photo below) with roots attached on their under surface and the buds of spears that are just beginning to develop sticking up. UC 157 hybrid is a good variety for this area--it tolerates warmer winters and is resistant to Fusarium. When buying crowns, look for fresh, firm-fleshed roots. If they are shriveled or brittle, they may be old and won’t produce well, if at all. Plant crowns while they are dormant.

Plants need full sun, good drainage, and, most important, well-prepared soil enriched with lots of organic matter (well-rotted manure, compost, bone or blood meal, leaf mold). Asparagus is a good candidate for raised beds. Dig a 6 inch deep trench 12 to 18 inches wide and spread crown roots over slight mounds of soil spaced 12 inches apart cover with 2 to 3 inches of soil. As plants grow, pull soil over the crowns until the trench is filled.

Let spears grow the first year without harvesting any spears (this allows for good root growth) after spears shoot up, let them leaf out (picture below) so that the foliage can nourish the growing roots and rhizome for future production. Then harvest lightly for 3 to 4 weeks the next year. The fleshy root system still needs to develop and store food reserves to support perennial growth in future seasons. Plants harvested too soon or heavily may be weak and spindly and the crowns may never recover. Future harvests may be for 6 to 10 weeks per year.

Harvest spears daily during the harvest period when spears are 6 to 8 inches tall and the tips are still tight. If the asparagus is allowed to get much taller, the bases of the spears will be tough. Snap or cut off each spear just below the soil surface. Cutting too deeply can injure the crown buds that produce the next spears.

When harvest is over, allow spears to grow and leaf out. This helps transfer energy to the roots for good spear development the next season. Asparagus has an attractive, fern-like foliage that makes a nice garden border. The tall growth can shade out other plants, so keep this in mind when deciding where to site your asparagus bed. Some gardeners prefer to support the growing foliage with stakes and strings to keep it tidy. Cut the foliage down to 2 inch stubs after freezing weather or when the foliage turns yellow. A 4 to 6 inch mulch of compost, composted manure, leaves, or other material added at this time will help control weeds and add organic matter and nutrients.

Weed the bed each spring before the first shoots come up to avoid accidentally breaking off spears. During production, it is best to pull rather than hoe weeds, if possible. A light mulch helps keep the soil surface from becoming too hard for the shoots to break through easily. Irrigate the bed during the summer for good spear production.

For additional information, see Growing Asparagus in the Garden (PDF) from the UC Davis Vegetable Research and Information Center. Click thumbnails:

What & When To Grow

Winter is the time to grow cool and cold-loving vegetables you love to eat.

I’ve had success with broccoli, kale, mesclun mix (an assortment of salad greens including leaf lettuces, mache, arugula, mustard, spinach…), Brussels sprouts, parsley, chives, and root vegetables including radishes, Swiss chard, and carrots.

This is not the time for heat-loving plants like tomatoes or peppers.

You want the plants to be well-established in their beds before the bitter cold (and damp) sets in.

Protective housing will prevent them from freezing (to death).

Snow is not actually the most destructive element: it’s icing up that can kill the plants.

Botanical Interests has a selection of frost-tolerant seeds here:

Watch the video: Top 8 Cold Hardy Crops That Thrived During Polar Vortex Zone 5

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