A cold-hardy leafy green that produces heavily from late summer through winter, with flavor that deepens after frost.
Brassica oleracea var. sabellica · also called borecole, curly kale
Windows are counted from the average date of your last spring frost.
Kale tolerates hard frost and keeps producing long after most vegetables have quit, giving you fresh greens well into winter. A single planting of four to six plants supplies a steady harvest for months with minimal intervention.
A little history. Kale is one of the oldest cultivated forms of Brassica oleracea, retaining a loose, non-heading growth habit close to the wild ancestor. Cold temperatures cause the plant to convert stored starches to sugars, measurably sweetening the leaves.
Sow seeds ½ inch (13 mm) deep, and aim for 18 inches (45 cm) between plants once thinned. Sow seeds 0.25–0.5 inches deep and keep the top half-inch moist until sprouts show; do not let the seedbed crust over. Seedlings emerge in 5–10 days.
Either works well; needs at least 12 inches of soil depth and 12 inches of horizontal space per plant. In containers: 5-gallon pot minimum; 7–10 gallon preferred for full-sized plants.
Water deeply twice a week in warm weather; once a week is usually sufficient once temperatures drop below 60 °F (16 °C). Water when the top inch of soil feels dry to the touch. Aim for about 1 inch per week including rain.
Side-dress (scatter fertilizer along the row and water in) once at planting and again 4 weeks later. What to use: nitrogen-forward fertilizer such as blood meal, fish meal, or a 5–3-3 organic blend.
Remove yellowing lower leaves promptly to improve airflow. If a flower stalk begins to form, cut it out immediately to redirect energy to leaf production.
It's ready when harvest outer leaves once they reach 8–10 inches long and are deep green and firm. Leaves smaller than a hand are immature; leaves yellowing at the base are past peak. Snap or cut the lowest, outermost leaves first, leaving the central growing tip and at least 4–6 inner leaves intact. Work upward over successive harvests to keep the plant producing.
Unwashed, in a sealed plastic bag in the refrigerator crisper drawer for up to 1 week. Blanch and freeze for storage up to 8 months.
Sow a second batch 3–4 weeks after the first for a staggered harvest; a late-summer sowing timed to mature in cool fall weather typically outperforms a spring crop in flavor.
Garlic
Garlic's strong smell can help hide kale from aphids and cabbage moths that locate host plants by scent. Plant a row along the bed edge rather than a few scattered cloves, since the effect depends on volume.
Onion
Onion foliage carries the same pungent smell as garlic and often reduces early aphid landings on nearby kale. Its narrow leaves take little room, so it fits between kale plants without shading them.
Nasturtium
Cabbage worms and aphids often settle on nasturtium in preference to kale. It only works if you check the nasturtiums weekly and pull or treat the infested growth, otherwise it becomes a nursery feeding the whole bed.
Dill
Let a few dill plants flower and the flat umbrella of tiny blooms feeds hoverflies, lacewings, and the small parasitic wasps that attack cabbage worms and aphids. Keep it at the bed edge so it does not shade young kale.
Celery
Gardeners have long paired celery with cabbage-family crops, and both are said to benefit. No mechanism has been demonstrated, but they share a taste for steady moisture and rich soil, so growing them side by side is easy to manage.
Strawberry
Old companion charts keep strawberries and cabbage-family crops apart, though no mechanism has been shown. The practical case is simpler: strawberries occupy a bed for years, while kale needs a four-year break from that ground.
Tomato
Both are heavy feeders drawing hard on nitrogen and water in the same top foot of soil, and a caged tomato throws enough shade by midsummer to slow kale beneath it. Give each its own row.
Give the cabbage family 4 years away from this spot before any of its relatives return.
The tomato family, the pea and bean family or the carrot family thrive in this ground next season.
Kale is a heavy feeder and leaves the bed short on nitrogen, with cabbage-family root diseases lingering in the soil. Keep all cabbage-family crops out of this ground for 4 years. Follow with legumes to rebuild nitrogen, or with nightshades or the carrot family.
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