This sturdy green is always at the top of the list of the most nutritious veggies, full of vitamins, minerals, antioxidants, and fiber. It's easier to grow than most of its cabbage family relatives, being less troubled by the many pests that afflict this clan, and its cold hardiness lets you plant early in the spring and harvest late into the fall, even into the winter months if you give it some protection. And it’s delicious lightly steamed and tossed with some olive oil, added to soups and casseroles, or raw in a salad.
Varieties: Kale is the belle of the vegetable garden ball. Blue-green curled ‘Winterbor’ kale is as lovely as a bouquet; 'Redbor' is a stunning, deep-purple version that makes an eye-catching garnish. Lacy-leaved 'Red Russian' provides color and texture. Lacinato, also called Tuscan or dinosaur kale, has long, puckered leaves that are especially tender and is more heat tolerant than other types of kale. 'Beira', with wide, collard-like leaves, is traditional in Portuguese kale soup.
Site: Full sun and fertile, well-drained soil with several inches of compost worked in prior to planting. Because it’s so attractive as well as nutritious, kale is a great choice for edible landscaping. Consider combining it with flowers and herbs in containers or garden beds rather than limiting it to the vegetable garden proper.
When to Plant: Kale tastes best when it ripens in cool weather. For the earliest spring crop, start seeds indoors 8-10 weeks before your last frost date; then set out hardened off seedlings 4-6 weeks before the last frost date. Sow seeds directly in the garden as soon as the soil can be worked in the spring. For a fall crop, sow seeds about 2 months before the expected fall frost date. While seeds for a fall harvest can be sown directly in the garden, hot summer soil often results in poor germination. You may have better success starting seeds in pots and transplanting seedlings. Direct sow seeds for “baby” kale monthly in succession up until the fall frost date.
Planting: Plant seeds ¼ to ½ inch deep. Thin to 12-24 inch spacing when seedlings are a few inches tall. Set transplants 12-24 inches apart. Sow seeds for “baby” kale by planting seeds in bands or wide rows. Space seeds about 1½ inch apart or broadcast seeds and thin to this approximate spacing.
Culture: Kale is shallow-rooted and does best with consistent soil moisture. A 3-inch deep layer of organic mulch will help retain soil moisture, keep weeds down, and avoid the damage to roots that might occur when weeding. Give kale a boost mid-season with an application of a soluble fertilizer such as fish emulsion.
Troubleshooting: While common cabbage family pests such as cabbage worms and flea beetles are potential problems, kale is generally less troubled by them than it relations, with the exception of cabbage aphids, which can be especially troublesome on fall crops. Aphids can be knocked off plants with a strong stream of water from a hose or controlled with insecticidal soap sprays. In the southern half of the country, harlequin bugs, a type of stink bug, can be problematic. Crush the black and white barrel-shaped eggs and handpick the orange and black adults and nymphs. Growing kale under lightweight floating row covers is an easy way to exclude pests. Rotate the location of kale and other cabbage family members to reduce the likelihood of disease problems.
Harvesting: Kale tastes best when it ripens in cool weather; a few frosts make it taste even sweeter, as the cold causes starches in the leaves to change to natural sugars. Cut individual outer leaves when they are of usable size or harvest the entire plant by cutting it at its base. In cool fall weather, harvesting leaves individually lets you enjoy an extended harvest. In milder areas (Zone 7 and south) you may be able to harvest throughout the winter. “Baby” kale is ready for harvest 3-5 weeks after planting. Baby kale can be grown as a “cut and come again” crop for multiple harvests.
- Kale enjoys a massage! Rubbing mature kale leaves with your fingers breaks down their cellulose, causing them to wilt and become silky, rather than rubbery, and takes away their bitter edge. Remove the tough central rib, toss leaves with a little lemon juice, olive oil, and a pinch of salt, then rub them together vigorously for two or three minutes, until they turn limp and their color changes to deep green. Sounds weird, but tastes great! Massaged kale will keep in the frig for several days in a sealed container.
- Although kale may seem like the trendy “veggie of the moment,” it’s been cultivated for centuries. Most likely descended from wild cabbages in the Mediterranean region, it was grown by Romans at least 2000 years ago.
- Kale has its own holiday! National Kale Day is celebrated on October 5. Check out the NKD website for more kale information than you can imagine – and some tasty recipes too! Here’s their recipe for Kale Lentil Tacos –great Meatless Monday fare!
For more kale recipes and ideas for curriculum connections, check out these materials from Vermont Farm to School.