Kale
How to grow Greens
For all greens, nitrogen is a necessity - the more nitrogen that is available,
the bushier and leafier your greens will be. Prepare your soil with a
nitrogen boost before planting, then side dress with nitrogen throughout
your growing season to maintain leaves.
Also, temperature is a key factor with greens. Most can withstand light
freezes, especially when covered with a plant-protector fleece. However,
temperatures above 75oF will usually cause most greens to bolt (begin
flowering to produce seeds, ie, the end of their season) - it’s important to
understand your area’s temperatures in order to decide if fall or spring
growing is better for your greens: in southern climates with hot summers
and mild winters, fall is the best growing season, while in northern
climates with longer springs and harsher winters, early spring planting
gives the best production. If you’re unsure, you can always start your
greens in the fall and cover them as needed. A hard freeze can kill your
greens, but light freezes will often make the leaves taste crisper.
Pests are similar on most greens as well. Cabbage loopers and other types of caterpillars are drawn to leafy greens, but as they are mostly grown in cooler weather, pests are often a sign that it is too warm and the plant will bolt soon. Flea beetles, cucumber beetles, harlequin bugs, and aphids can be prevalent in greens, so always be sure to wash your greens before eating. Because greens are directly edible, take care with any pesticide use and be sure it is marked for vegetable gardening on the label.
If growing microgreens, these are often best done indoors, in controlled environments. Add sterilized potting soil (to prevent fungus and gnats) to a propagation tray, or use seed mats. Liquid fertilizer is best for this use, but isn’t a requirement. With microgreens, spacing isn’t really an issue, because your seedlings will be used when small. Microgreens do need to be kept moist, but too much moisture can promote mold. Harvest when your microgreens are of a usable size. Use scissors to cut the tops, leaving the roots intact and leave a few lower leaves if you want them to regrow.
Kale
Kale can be started in any weather, though it does best between 20-80ºF. Below 20ºF, it will die, and above 80ºF, it will turn bitter and tough. Seeds can be planted directly or indoors, about 1/4” deep, but sprout best in acidic soil at temperatures around 70ºF. Once the seedlings are a few weeks old, thin to 8-12” apart. If planting in fall, put your seeds in full sun, but if planting in spring or summer, go for partial shade. Keep kale well watered to make sure the leaves stay sweet.
Your kale will be ready to harvest when the leaves are about the size of your hand. Only pick about a handful of leaves with each harvest, and avoid picking the bud that’s at the top center of the plant/stem, as this will keep the plant producing. Extend your harvest with row covers and mulch. As your kale gets older, the stem gets longer and can “wander” out of its row. If your kale plant gets too large, consider pulling the plant. If you’re wanting to harvest seeds, kale is a biennial, meaning it takes two years for the plant to go to seed. You would be better off planting in a container that you can move it if there is a hard freeze. Kale can be eaten raw or cooked, but the small, tender leaves are the best for raw. Be sure to thoroughly clean your kale. Insects can get caught in the crinkles of the leaves.