Kale - Key Growing Information

A view of a recent kale trial, a lacinato type growing in the background and a curly variety in the foreground.
SCIENTIFIC NAME: Brassica oleracea
CULTURE: Kale prefers a fertile, well-drained soil high in organic matter with a pH range of 6.0–7.5. Consistent moisture will produce the highest-quality leaves. For baby-leaf production, see the Baby Leaf Brassica Greens culture.
DAYS TO MATURITY: From direct seeding; subtract about 14 days for days to maturity from transplant.
DIRECT SEEDING: Plant from early spring to approximately 3 months before expected fall frost. For bunching: sow 3–4 seeds every 12–18", ½" deep, in rows 18–36" apart. Thin to 1 plant per group.
EARLY SPRING CROP: Use varieties suited to warm-season production. Sow 2 seeds per cell in 50- to 72-cell plug flats, 3–4 seeds/in. in 20-row flats; or, in outdoor beds ¼" deep. Seedlings should be ready to transplant in 4–6 weeks. If possible, keep soil temperature over 75°F (24°C) until germination, then reduce air temperature to about 60°F (16°C). Transplant outdoors 12–18" apart in rows 18–36" apart. Kale prefers cooler growing temperatures, between 55–75°F (13–24°C), optimum being 60–70°F (16–21°C), but will produce good crops under warmer, summer conditions.
FALL CROP: Start seedlings as above in May and transplant to the garden in June–July. To ensure mature heads, seed the crop early in areas where heavy freezes occur early in fall.
WINTER CROP: Successful kale crops can be grown where winters are mild and temperatures rarely fall below 32°F (0°C). Transplants can be set out from September to February in these regions.
DISEASE: Black rot and black leg can be seedborne. We only stock seed lots that have been tested free of black rot in a sample of 30,000 seeds. Individual seed lots have been tested free of black leg in a sample of 1,000 seeds. NOTE: A disease-free test result means that in the sample tested, the pathogen targeted was not found. It does not guarantee a seed lot to be disease-free. However, no method of seed treatment can positively ensure freedom from disease. We are glad to help with specific questions.
INSECT PESTS: Kale is not as afflicted with pests as are other brassica crops such as cabbage. Apply row covers at the time of planting to exclude pests from the crop. Control cabbage worms and loopers with Bacillus thuringiensis (Bt).
HARVEST: Beginning about 2 months after planting, harvest by clipping individual leaves. Kale is very hardy, and the eating quality will improve into the late fall with light frost. Late-summer sown or planted collards can be wintered in cold frames or hoophouses, or in the open in mild regions, to extend the season. Protecting with row covers can extend the harvest period.
AVG. SEEDING RATE: For bunching: 1,000 seeds/220', 1 oz./1,110', 1 lb./24,000'.
TRANSPLANTS: Avg. 6,400 plants/oz.
SIZED SEEDS: "Sized" seeds have been sorted so they are roughly the same size. This consistency allows for more accurate spacing with mechanical seeders and more even germination. Kale seeds are sized, except when noted in the product description.
SEED SPECS: SEEDS/LB.: Avg. 124,000.
PACKET: 100 seeds, sows 22'.