Cold Hardy Crops and Heat Tolerant Crops

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  Arugula is cold-tolerant up to 22 degrees Fahrenheit.
  Photo by iStock
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  Beet greens are heat tolerant.
  Photo by iStock
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  Cold frames help keep greens warm in cool temperatures.
  Photo by iStock

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.”

Cold-Tolerant Greens

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

Heat-Tolerant Greens

Although hot weather isn’t ideal for greens, these choices can withstand summer temps.