Think you have to live in the south to grow collards? While it’s true that gardeners in those sunny states have already tasted their first crop of this nutritional powerhouse this year, there’s no reason why northerners can’t grow and enjoy this cabbage family relative. In fact, it’s collards cold-tolerance (as low as 10 degrees), that makes them a favorite in winter gardens in USDA Plant Hardiness Zones 8 and higher. And they taste sweeter once they’ve been nipped by a frost or two.
Whether you buy transplants or start from seed, now is the time to plant collards in zones 7 and northward, before the weather gets too hot. The general rule is to plant in spring 3 to 4 weeks before the last frost. (Both southerners and northerners can sow another crop in late summer for a fall and early winter harvest.)
Pick a sunny spot – at least five hours of sun a day. Pay attention to soil pH. Collards need a pH of 6.0 to 6.8 or they can develop a disease called clubroot. Sow or plant 18 to 24 inches apart in soil amended with compost. Mulch after planting.
Collards are thirsty plants, needing 1-1 ½” of water a week. Their flavor will suffer with less than that, so plan to supplement rainfall with manual irrigation. Avoid splashing soil on the undersides of the leaves, as this can invite disease. Don’t plant collards or any cole crop in the same place every year; leave at least two years between plantings so diseases don’t build up in the soil.
Insects that eat cabbage will also attack collards, so be on the lookout for cabbage loopers, cabbage worms, aphids, slugs, flea beetles and the like.
Fertilize plants with fertilizer high in nitrogen, and feed frequently – every two weeks – to keep the plant producing leaves. Harvest the leaves when they are about 10” long and still tender. Pick leaves from the bottom of the stem upwards – as they grow they will get a lanky, top-heavy look, but this is normal. Wash the leaves thoroughly before using them. Collards are high in phytochemicals and antioxidants, and a good source of beta carotene and calcium.
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