Kale, the Power Vegetable (cont)
By: Frank Morton
When, Where, and How to Plant
In western Oregon, we sow seed in the last half of July. Gardeners in colder climates should sow earlier, and those in milder areas a little later. It's better to grow kale slowly through the warm periods, so it will be hardy into the post-frost season, when the flavor is best. Space plants 14 inches apart in all directions, or 12 inches apart in rows 2 feet apart. Most kales will grow into whatever space is provided, having larger leaves and thicker shoots as more room is available. Plants mature in 50 to 80 days.
Soil, water, nutrients. Growing requirements are about the same as those for cabbage: fertile soil, neutral pH, plenty of calcium, and water as needed. Excess nitrogen will cause sappy, frost-sensitive tissues.
Saving your own seed. By letting kales progress beyond the leafy stage, you get to try the delicious broccoli-like flowering shoots. They're so numerous and persistent, you'll always have plenty that go beyond the bud stage. These flowering buds make excellent edible blossoms to garnish salads and soups, and you'll find blossoms abuzz with bees and beelike syrphid flies. The earliest seed is ready by July, when the pods begin to turn dry and brown.
Pests and diseases. Botrytis (head rot) and black rot are the only diseases we find in our location, though kale may contract other diseases that affect the Brassica genus in your area. Botrytis causes leaves and the growing point to break down during wet, cold weather. Black rot causes spotting on leaves before the plant is mature. Both diseases are seed-borne and spread by spores on the wind or in the soil.
Cabbage aphids can be troublesome to drought- or heat-stressed plants at the end of summer. In our garden, syrphid fly larvae are major aphid predators on autumn kale. If these or ladybird beetles aren't doing the job, spray insecticidal soap, or blast the aphids away with a spray (high pressure, low volume) from the hose.
You may see greenish or yellow-green syrphid fly larvae among the aphids, chomping a hole right through the colony. In time these larvae will mature into hover fly or bee fly adults. Syrphid adults are very keen on kale flowers, where they drink nectar, mate, and eat the pollen that's required for egg laying. You see their white, rice-shaped 1/16-inch-long eggs attached to aphid-infested leaves, where the larvae will emerge and begin to dine.
If you find brassy-colored aphid "mummies," this is a sign that tiny parasitic wasps are aiding your efforts, and more of these beneficial wasps will soon hatch out of the parasitized aphids. Leave the mummies in place.