Since kale is probably the prettiest member of the cabbage (brassicas) family, it is often grown just as a beautiful addition to a garden because of its variety of colors and leaf shapes. It also is one of the more nutritious vegetables mother nature designs with high levels of vitamins A and C plus a particularly high level of calcium. Kale does not form a head like cabbage, and although the leaves can be eaten raw when very young, it is considered one of the cooking greens. Our ancestors considered almost all greens to be “pot herbs,” and it is a relatively modern practice to eat greens raw.
Plant and harvest kale throughout the growing season. From seed to harvest, kale takes about eight weeks. Kale is a hardy, cool-weather vegetable and can be planted in early spring when the soil temperatures are in the 60s and before the last frost or in late summer about 10 weeks before the first frost for a fall harvest. Plant transplants or sow seeds directly in the garden. Seeds should be sown about one-half inch deep and seeds or seedling transplants need 12 inches of space for the mature plant.
Pick a sunny location, and because kale is a very heavy feeder, it benefits from plenty of nitrogen afforded by well-composted soil. If you have average soil, a light fertilizing once with a liquid fertilizer such as fish emulsion helps once kale is established. Kale seeds germinate in about 10 days and grow slowly at first but need constant moisture because the roots are shallow and the plant can dry out. High heat plus under watering makes the leaves tough and bitter.
Harvest kale using the “cut-and-come-again” method. Use scissors to cut individual leaves from the outside, and the plant will continue to produce from the inside. Pick the leaves at the top last to keep the plant producing. Once the leaves mature, kale can be too tough to eat raw in a salad and become candidates for braising or sauteing. A bonus for our area is that the flavor improves significantly when the plant is exposed to a frost and is best when picked from under a blanket of snow. A frost sweetens kale overnight, and if the fall cooling has been gradual, kale even can survive temperatures of 10 degrees. As weather cools, a plant’s carbohydrates or sugar reserves go into storage and act like antifreeze allowing the plant to withstand low temperatures by lowering the temperature needed for water in the plant tissue to freeze. The cool-weather build-up of sugars in vegetables like kale (and brussels sprouts) make them sweeter tasting. If you harvest frozen leaves, cook them immediately before they thaw.
After the avalanche of harvesting summer crops is over and the canning is done, deep blue-green or purple-red kale plants wait patiently as the days cool. They aren’t looking or feeling neglected but are starting to taste their best and even making a depleted garden look gorgeous. For vegetable gardeners, there is not much more you can ask for than that.
Jane McLeod is a master gardener through the CSU Extension Routt County. Call 970-879-0825 with questions.