Cold Hardy Crops and Heat Tolerant Crops
Greens for Every Season
Gardeners in different climates will plant at very different times. When figuring out the ideal time for you to plant greens—or anything else—it helps to know your average frost dates.
When you’re looking for planting directions, start with the seed packet or website of the seed company for advice on the specific vegetable variety you’re growing. (Another great source is Cornell University.) In any planting instructions, you’ll frequently find references to “average last frost date” for spring planting, and “average first frost date” for fall planting. You can look yours up by ZIP code at Dave’s Garden.
In general: Cold-tolerant greens can be planted well before your average last frost date in spring. For less hardy plants, Malabar spinach for example, you’ll usually be advised to wait until one or two weeks after your last spring frost. For fall planting, keep in mind that even for cold-hardy plants, you need to give them time to start growing before the temperature drops. For that reason, you’ll usually see instructions such as “plant up until three months before first average fall frost.”
These plants can weather freezing temperatures and hard frosts for short periods. The figures below show minimum temperatures tolerated by these plants, as recorded by Southern Exposure Seed Exchange, including some specific varieties tested by the seed company.
• Arugula: 22 degrees
• Collards: 12 degrees
• Endive, Escarole: 25 degrees
• Kale, ‘Even’ Star Smooth Kale’: 6 degrees
• Kale, ‘Red Russian’: 15 degrees
• Kale, Scotch types: ‘Squire’, ‘Vates’, ‘Siberian’: 12 degrees
• Lettuce, ‘Devil’s Tongue’,‘Red Salad Bowl’: 25 degrees for large leaves
• Lettuce, ‘Bronze Arrow’, ‘Winter Density’,‘Rouge d’Hiver’, ‘Red Sails’: 15 degrees and lower for small leaves
• Mustard, ‘Even’ Star Tender Tat’, ‘New Star Mustard’, ‘Chinese Thick-Stem’: 6 to 12 degrees
• Mustard, ‘Red Giant’, ‘Southern Curled’: 25 degrees
• Spinach, ‘Long Standing Bloomsdale’, ‘Winter Bloomsdale’: 10 degrees for large leaves, 5 degrees for small leaves
• Swiss chard: 25 degrees
Although hot weather isn’t ideal for greens, these choices can withstand summer temps.
• Amaranth greens
• Beet greens
• Malabar spinach
• New Zealand spinach
• Some types of mustard, including mizuna, ‘Red Giant’ and ‘Greenwave’, among others
• Some types of spinach; look for varieties advertised as “long standing” or “slow to bolt”
Other Ways to Deal with Cold Temperatures
If you live in a particularly cold climate, choosing cold-hardy vegetables is a start, but you’ll want to take additional measures. One option is to simply try bringing plants inside: Many greens such as lettuce and spinach make good container plants.
Another strategy is to give greens some added protection during winter by growing them in cold frames, which can be as basic as a wooden box with an old window on top, placed right on top of your garden soil. Not only does a cold frame protect fall crops through the winter, but it warms up the soil in spring, allowing earlier planting. Learn more at Make a Cold Frame for Herbs.
You might also want to explore other techniques that gardeners in cold climates have developed to grow year-round. Great resources for more information are two books by Maine gardener Eliot Coleman, Four Season HarvestandThe Winter Harvest Handbook. Also on this topic, check out The Four Season Farm Gardener’s Cookbook by Coleman and Barbara Damrosch.
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