How to Grow Kale
Kale is often direct-sown in the garden, but you will have more control over your planting schedule if you grow transplants in plug trays. If you intend to hold the plugs for a while, larger cells found in 72 or 36 cell trays will give you more leeway about when to transplant. Given its preference for cool conditions, kale is traditionally a fall crop. Sowing seed 70 days before the first fall frost will give your kale time to get big as the nights grow cold. It is more difficult to get good quality kale in the spring given the warming weather conditions, but you may succeed with a late winter/early spring sowing estimating 50-70 days to your first harvest.
Like other brassicas, kale prefers soil high in organic matter, nitrogen and calcium with good drainage and a pH of 6.5. Drip irrigation can enhance the quality of kale. It likes moist soil for healthy development.
If you decide to direct-sow seeds, plant them 1" apart with 24-30" between rows. Thin to 8-10" between plants or up to 18" apart for the largest plants. Follow these spacing guidelines for transplants.
Kale requires little care after planting. Established plants benefit from mulch to suppress weeds and fish emulsion when it is transplanted and again at mid-season to keep it growing steadily.
Kale can be harvested by the leaf or by cutting the entire plant. If the outer leaves are tough, this argues for cutting the middle leaves only, allowing the young leaves in the center to keep growing for a prolonged harvest. You can continue harvesting using this method until hard winter conditions arrive. If you prefer to harvest the entire plant, this is best done when the leaves are small and tender. Kale leaves keep briefly. They are at their best for one day.
Kale is subject to the same pests as other cole crops, with flea beetles among the worst. They cut small holes in the leaves and can cause such extensive damage that they kill the plant. Row covers can be used to exclude flea beetles when they are at their worst.
Seeds can be kept for up to five years under good storage conditions.