Cool-season vegetables are for planting and growing in late winter, early spring or in late summer, autumn, and early winter. These crops do best in temperatures between about 40°F and about 70°F (4-21°C). Many can withstand temperatures colder, but few can thrive in temperatures warmer.
Make sure that cool-season crops planted in spring have enough time to reach maturity before the weather turns warm. Conversely, make sure cool-weather crops planted in late summer and early autumn have enough time to reach harvest before the first heavy freeze or big snow storm.
Check the seed packet or the plant markers that comes with vegetable starts to see how many days the seed or plant requires to reach maturity. Then plan your sowing, transplanting and harvesting accordingly–marking your calendar.
Once the weather warms, cool-season crops will be done and you will want to plant warm-season crops.
Hardiness is a term used to describe a cool-season plant’s ability to survive winter without protection. The terms “hardy” and “semi-hardy” are important when deciding which crops to plant where you live.
Hardy vegetables can tolerate a hard frost—about 25° to 28° F (-3 to -2°C). The hardiest crops are kale, spinach, and collards which can tolerate temperatures in the low 20s and high teens.
The hardy crops are:
- Brussels sprouts
- English peas
- Mustard greens
Semi-hardy vegetables can tolerate a light frost–usually about 29° to 32°F (-2 to 0°C). They are good for spring and fall gardens.
The semi-hardy crops are:
- Chinese cabbage
- Irish potatoes
- Swiss chard
You may find that transplants or vegetable starts work best in autumn. That way summer crops can remain in the garden for a few weeks longer. Of course, starts begun under cover in spring and later transplanted into the open extend the growing season as well.
Also in the coldest growing regions, a double cover of both a tunnel and cold frame may keep the soil from freezing.
Suggested cool-season vegetable crop varieties and timing:
• Arugula. Easy salad choice matures in less than 50 days. Arugula is mild flavored when grown in cool conditions; plant by mid-autumn in frame or tunnel for harvest throughout winter; plant again in January.
• Beets. Choose varieties that mature in 55 days or less; try to seed beets 10 weeks in advance of first frost: ‘Bull’s Blood’ (40 days) early harvest heirloom; ‘Chioggia’ (54 days) beautiful ringed heirloom; ‘Golden Globe’ (55 days) sweet flavored heirloom; ‘Red Ace’ (53 days) honey-sweet hybrid.
• Broccoli. Choose a broccoli variety maturing in about 60 days and good side-shoot production: ‘Early Dividend’ (46 days) excellent sideshoot development; ‘Patron’ (60 days) mid-late season hybrid; ‘Arcadia’ (70 days) cold tolerant; ‘De Cicco’ (60 days) mild-flavored heirloom; ‘Early Green’ (65 days) extended harvest from side shoots; ‘Gypsy’ (58 days) heat tolerant; ‘Packman’ (55 days) hybrid.
• Brussels sprouts. Choose varieties that mature in 100 days or less. Long-season cool-weather Brussels sprouts are always best started from transplants. Taste improves with each fall frost. Can go 6 to 9 weeks past freeze with protection. ‘Long Early Dwarf Danish’ (95 days) freezing temperature enhances flavor; ‘Oliver’ (90 days) early harvest; ‘Jade Cross’ (100 days) holds well in poor weather.
• Cabbage. Choose cabbage varieties that mature in less than 90 days. Harvest before freeze. Store head and plant will keep a long time. ‘Gonzales’ (60 days) small head; ‘Ruby Perfection’ (85 days) hyrbid for fall storage; ‘Fast Ball’ (45 days) compact head; ‘Earliana’ (60 days) great flavor.
• Carrots. Choose varieties that mature in less than 60 days. Carrots can be stored in the ground where soil does not freeze. Grow in a cold frame protected from a hard freeze. In severe winter areas, cover carrots with straw inside the frame.
• Cauliflower. Choose cauliflower varieties that mature in less than 60 days. Best started 10 weeks before the first fall frost. ‘Snow Queen’ (50-60 days) easy to care for hybrid; ‘Violet Queen’ (54 days) early hybrid; ‘Early Dawn’ (45 days).
• Chard. Choose chard varieties that mature in 60 days or less. Pick leaves as they mature and the plant will produce more. Will keep producing until hard frost; frozen chard leaves will come back with a thaw. Grown in a cold frame can produce throughout the winter. ‘Argentata’ (55 days); ‘Fordhook Giant’ (58 days) mild-flavored heirloom; ‘Lucullus’ (50-60 days) long-bearing heirloom; ‘Rhubarb Chard’ (60 days); ‘Ruby Red’ (60 days).
• Corn salad. Germinates best in cool soil. Corn salad is very cold hardy. Reaches maturity in less than 50 days. Harvest whole plant at about 4 inches or cut and come again. Plant in a cold frame for all winter use.
• Endive. About 90 days to maturity, but you can harvest earlier. Plant endive late summer for a fall and winter harvest, early spring for a summer harvest. Escarole is hardier but both will do well through winter with cold frame protection. Endive: ‘Full Heart Batavian’ (85 days), ‘Large Green Curled’; Escarole: ‘Nuvol’ (50 days).
• Garlic. Plant cloves in fall to establish good root growth, not top growth. Garlic will mature in 7 to 8 months. In late fall cover the growing bed with straw and top dress with compost. Garlic matures in summer when the tops fall over.
• Kale. The inside leaves are generally tastier than the outer leaves. Kale can be harvested from under the snow. Low-growing varieties are best for cold frames; taller varieties are not as cold hardy. ‘Vates Dwarf’ (65 days) low growing; ‘Winterbor’ (65 days), ‘Blue Curled’ (65 days); ‘Red Russian’ (25 days) tender heirloom; ‘Toscano’ also called ‘Luciano’ (30 days) heat-tolerant savoy heirloom; ‘White Russian’ (50 days) frilled, dissected heirloom,
• Kohlrabi. Best grown in fall and winter; grow kohlrabi outdoors until a hard freeze then harvest and store; grow in coldframe or plastic tunnel for longer harvest. ‘Grand Duke’ (48 days) hybrid; ‘Early White Vienna’ (55 days) open-pollinated; ‘Purple Vienna’ (60 days) open-pollinated.
• Leeks. Start leeks for winter harvest in early spring, a long season crop. Bunching leeks will grow to pencil size in 8 weeks or so; they can be harvested as the spring planted leeks grow on to maturity. Fastest maturing varieties are ready in about 80 days. ‘Electra’ (145 days), ‘Titian’ (90 days); ‘Varna’ (70 days).
• Lettuce. Lettuce season is spring, summer and fall in cold regions; fall, winter, and spring in very warm regions. Choose varieties that mature in 60 days or less. Lettuce can take only so much freezing and thawing, even in a cold frame or tunnel; plants should reach harvestable size by early winter; winter varieties can survive through winter in a cold frame if protected from multiple freezes. Choose leafy varieties rather than heading varieties for earliest harvest. Looseleaf varieties are fast growing, less than 50 days. Butterhead varieties form a head and require about 75 days. Romaines require about 70 days. Choices: ‘Winter Density’, ‘Green Wave’; Butterhead: ‘Dear Tongue’ (46 days” heirloom buttercrunch; ‘Dark Green Boston’, ‘Summer Bibb’; Romaine: ‘Cinnamon’ (65 days), red romaine heirloom; ‘Parris Island’, ‘Valmaine’; Looseleaf: ‘Lolla Rosa’ (53 days) looseleaf heirloom; ‘Salad Bowl’, ‘Oak Leaf’, ‘Green Ice’, ‘Red Sails’, ‘Ruby’; ‘Simpson Elite’ (53 days) heirloom.
• Mesclun. Grow mesclun like lettuce but ready in half the time, about 25 days.
• Mustard Greens. Sow mustard greens in fall for harvest throughout winter. ‘Tatsoi’ (45 days); ‘Mizuna’ (40-60 days).
• Onions. Bulb onions are planted in winter for late spring or summer harvest, usually 90 to 120 days. Bulb onion thinnings can be used as green onions. Bunching onions and green onions can be harvested in about 70 days. Bulb onions: ‘Fiesta’, ‘Yellow Sweet Spanish’, ‘White Sweet Spanish’, ‘Southport Globe’, ‘Stockton Yellow Globe’. Small bulb and bunching: ‘Red Beard’ (85 days) bunching, grow through winter, harvest summer; ‘Red Long Tropea’ (90 days) red bulbs, harvest mid-, late summer; ‘Rosa di Milano’ (110 days) barrel shaped; ‘White Spear’ (65 days) late bunching.
• Parsley. Varieties all mature in about 80 days, but parsley takes at least 21 days to germinate. ‘Darki’, ‘Drausa’, ‘Italian Dark Green’.
• Parsnips. Hardiest of root crops, plant parsnips early summer for next spring harvest maturing in about 120 days; winter over with no protection even in coldest regions. Dig parsnips when soil has thawed. Parnsips can store for 4 to 6 months.
• Peas. Sow peas for autumn harvest at least 60 days before first light frost; leaves and vines are hardy, not the pods; freezing will damage the pods. Use an A-frame plastic cover to extend the season by 3 to 4 weeks. Low-growing varieties come to harvest earlier. China, snow or sugar peas: ‘Dwarf Grey Sugar’ (65 days); ‘Mammoth Melting Sugar’ (75 days). Garden peas: ‘Freezonian’ (63 days); ‘Green Arrow’ (65 days); ‘Maestro’. Snap peas: ‘Sugar Ann’ (56 days); ‘Sweet Snap’ (60 days), ‘Sugar Rae’ (70 days), ‘Sugar Daddy’ (75 days); ‘Super Sugar Snap’ (60 days).
• Radicchio. Radicchio matures in about 60 days. Heads will survive for all winter harvest in the protection of a cold frame but it is best to get up to size before weather gets too cold.
• Radish. Can be one of the last crops sown in fall (and one of the first in spring); radishes grow best in cool, moist conditions. Radishes can be harvested in as early as 25 days and will keep in cool soil up to 60 days. ‘China Rose’ (52 days); ‘Tama’ (65 days); ‘Cherry Belle’ (25 days), ‘Champion’ (24 days), ‘April Cross’ (45 days), ‘Icicle’ (30 days); ‘Snowbelle’ (26 days).
• Spinach. Spinach will germinate and grow at temperatures just slightly above freezing and continue growing until freezing. ‘Indian Summer (39 days); ‘Winter Bloomsdale’ (45 days); ‘Olympia’ (45 days); ‘Tyree’ (45 days).
• Turnips. Turnips are best tasting when young adn tender. Choose varieties that mature in 40 days or less. ‘Market Express’ (38 days); ‘Tokyo Cross’ (35 days).