A Beginner's Guide to Planting, Growing, and Harvesting Kale

Mature kale leaves can be coarse, but several types are grown for their tender, palatable young leaves. Kale is an important leaf crop for early spring when the weather is too harsh for many other leafy crops.

Growing kale is relatively easy, and it's a nutritious leafy green that can thrive in various climates. Here's a step-by-step guide on how to plant, grow, and harvest kale:

When Should You Plant Kale?

Kale is a leafy, cool-weather crop that requires two months of cool weather to harvest. Kale is a biennial plant, a hardy brassica (member of the cabbage/mustard family). Cool-season crops perform best in most of the country in spring and fall. If you're wondering when to plant kale in your hardiness zone, base your planting dates around your first and last frost dates. For northern states, plant kale seeds and seedlings outdoors in early spring — roughly three to five weeks before your average last frost date. Remove plants when they start to go to seed (also known as bolting) when summer temps set in. Then, replant kale again six to eight weeks before your anticipated first frost date for a fall crop. If you live in a southern or coastal climate with mild winters, you can grow kale from late fall through the winter.

Choose the Right Variety

There are several varieties of kale, including curly kale, Lacinato (or dinosaur) kale, and Russian kale. Choose a variety that suits your taste and climate.

How Far Apart Do You Plant Kale?

On average, plant kale 18 inches apart in rows 2 feet apart. However, you should always defer to your variety's seed packet or plant tag for spacing instructions. For example, 'Lacinato' kale needs 2 to 3 feet of space, while 'Red Russian' kale spreads only a foot wide. If you're planting seeds, you can always plant them closer together, then thin your rows to your variety's recommended spacing once seedlings emerge.

Start with Quality Seeds or Seedlings

You can start kale from seeds indoors or purchase seedlings from a nursery. If starting from seeds, sow them indoors 6-8 weeks before the last expected frost.

How Deep Should You Plant Kale?

Always let your seed packet be your guide, but in general, plant kale seeds ¼ to ½ inches deep. Dig a hole twice as wide as the root ball for garden-ready plants and carefully place the plant at the same depth as its current container. Carefully cover with the surrounding soil.

What Are the Ideal Growing Conditions for Kale?

Temperature

Kale grows its most vigorous (and delicious) below 75 degrees Fahrenheit and can even handle temperature dips below 25 F. In fact, many gardeners think kale tastes better after a light frost. However, it turns bitter and tough in the dog days of summer.

Sunlight

Plant kale in full sun for maximum growth, receiving six to eight hours of direct sunlight per day. However, it's possible to grow kale successfully in partial sun, with just four to six hours of sunlight. In other words, full sun is best, but don't sweat it if your kale encounters a little shade.

Soil

Plant kale in fertile, well-drained soil. Test your soil and aim for a pH of 6.0 to 7.5. If you need to change your soil's pH, your test results will advise what to do. Before planting, work compost into topsoil for an instant nutrient boost.

Watering

Keep the soil consistently moist but not waterlogged. Kale requires about 1 to 1.5 inches of water per week. Water at the base of the plant to avoid fungal diseases. Opt for one to two deep waterings per week versus a daily spritz — less frequent waterings encourage roots to grow deeper and more robust.

Fertilizing

Kale benefits from a balanced fertilizer or organic compost applied at planting time. Side-dress with additional fertilizer during the growing season.

Mulching

Apply a layer of mulch around the plants to retain moisture, suppress weeds, and regulate soil temperature.

Companion Planting

Planting kale alongside companion plants like onions, garlic, and herbs can help deter pests.

Successive Planting

To ensure a continuous harvest, consider planting kale in succession every 2-3 weeks.

Winter Care

Kale is frost-tolerant and can often survive winter in many climates. In colder regions, you can provide extra protection with row covers or mulch.

Types of kale

There are five basic types of kale: curly kale (also called Scotch kale or borecole) with tightly curled leaves; broad-leaves kale (also called Siberian kale) with smoother leaves with frilled edges; Red Russian kale with frilly-edged blue-green leaves; black Tuscan kale (also called Dinosaur kale) with narrow almost blue leaves with a creped texture; and bicolored ornamental kales which are edible though commonly featured for their color in flower gardens.

• Curly kale (Borecole, Scotch kale) is one of the hardiest members of the cabbage family. Curly kale has deeply crinkled green or blue leaves; some varieties have deep curled purple leaves. Curly kale is grown for both mature leaves and young spring soots. Tall varieties grow to 36 inches (90cm) tall; dwarf types grow to 12 inches (30cm) high. Varieties include the hybrids ‘Darkibor’, ‘Fribor’, ‘Showbor’ and ‘Winterbot’. ‘Redbor’ and ‘Garna Red’ have red leaves. ‘Dwarf Green Curled Afro’ is an heirloom variety. ‘Showbor’ and ‘Starbor’ and mini varieties.
• Broad-leaved kale has flat rather than curled leaves. Broad-leaved kale is grown primarily for its spring shoots. These kales are faster growing than curly kale. Varieties include ‘Pentland Brig’ and ‘Hungry Gap’.
• Red Russian kale has attractive, frilly-edged, blue-green leaves that develop distinct purple and red tints as temperatures fall. This kale is mild-flavored and smooth textured. It grows to 27 inches (70cm) tall. It grows to maturity in about 50 days.
• Black Tuscan or Lancinato kale (also called black kale, black cabbage, Cavolo nero, palm cabbage, and dinosaur kale) produces tufts of long, narrow, almost blue leaves with creped texture. Black Tuscan kale is widely grown in Italy. It has distinctly flavored leaves often used in soups and in salads when picked young. It can grow to 4 feet (2m) tall. It grows to maturity in about 62 days.
• Ornamental kales and cabbages–these are highly decorative, brightly multicolored plants commonly grown as ornamental plants, but they can be used as a garnish. These have deeply serrated leaves. The colors deepen in cold weather.

Where to Plant Kale

Plant kale in full sun; plant kale in partial shade in warm regions. For optimal flavor, grow kale in cool weather.

• Plant kale with humus-rich, well-drained soil with a soil pH between 6.5 and 6.8.
• Kale grows best in loamy soil; add a moderate amount of well-rotted manure or compost to the planting bed ahead of plants.
• The flavor and texture of kale will decline when grown in light, sandy soils or heavy, clayey soils.
• Soil too rich in nitrogen can cause kale to grow extra-succulent which in turn can attract pests.

Kale planting time

• Kale is a cool-weather crop that can tolerate temperatures as low as 20°F (-6.7°C). Most varieties of Kale do not tolerate heat.
• Direct seed or transplant kale into the garden so that it comes to harvest before daytime temperatures exceed 80°F (26°C).
• Soil temperature must be at least 40°F for good germination of kale seeds.
• Start kale transplants indoors 6 to 8 weeks before the time you want to set them in the garden.
• Sow seed in the garden 4 to 6 weeks before the last frost in spring
• Set kale transplants in the garden from 5 weeks before to 2 weeks after the last frost in spring.
• In cool-summer regions, plant kale in early spring for summer to early fall harvest.
• In warm- and hot-summer regions, plant kale in late summer for harvest in late fall or winter.
• In mild-winter regions, kale can be sown in the fall for winter harvest.
• For a fall harvest sow seeds about 10 weeks before the first expected fall frost.

Planting and spacing kale

• Sow kale seed ½ inch (12mm) deep and spaced 3 inches (7cm) apart.
• Thin kale seedlings to 12 inches (30cm) to 15 inches apart when they are 4 to 5 inches (10-12cm) tall.
• Space rows 18 to 24 inches (45-61cm) apart.
• In growing beds with equidistant planting, set plants 15 to 18 inches apart.
• Set transplants with crooked stems up to the first leaves.
• Space dwarf or mini kales 6 to 8 inches (15-20cm) apart.

Growing kale in winter

Kale can be grown under cover–in a cold frame, plastic tunnel, or row cover– through the winter. In mild winter regions, kale can be harvested through the winter. Kale is a biennial and will start to grow again in the spring.

Where plants overwinter under cover, continue picking leaves through the winter and into spring. Growing kale under cover in winter will make leaves more tender. You can also overwinter kale in the garden with a protective mulch. In fall, pull earth up around the stem to the level of the lowest leaves then mulch thickly with straw or chopped leaves when frost is forecast. Kale that is well-covered will survive through the winter and even produce an early crop of new leaves in spring.

Watering kale

Keep kale well-watered for sustained growth and to keep leaves from getting too tough. Kale prefers damp, not soggy, soil. Be sure to water during the early stages of growth to ensure plants become well-established.

Feeding kale

Add nutrient-rich aged compost to planting beds in advance of planting. When kale seedlings are 4 to 5 inches tall, side-dress them with nitrogen-rich fertilizer such as rotted manure or blood meal, or water with manure tea. Side-dress kale with aged compost every 6 weeks. Overwintered plants should be fed with a seaweed-based fertilizer in spring to stimulate new growth.

Kale companion plants

Good companion plants for kale include beets, celery, herbs, onions, and potatoes. Do not plant kale with pole beans, strawberries, or tomatoes.

Caring for kale

• Kale is a very low-maintenance crop.
• Keep the planting bed weed-free for kale.
• Remove any old or rotting lower leaves as necessary.
• Apply mulch around the kale once plants are well-established.
• Mound straw around kale once it is 6 inches (15cm) high to prevent plants from touching the soil; soil easily sticks to kale’s often crinkled leaves.
• Dwarf plants can be covered with cloches or crop covers in autumn to make the leaves more tender.

Container growing kale

• Kale will grow best in a 12-inch diameter (30 cm) container that is at least 12 inches deep. There should be at least 3 gallons of soil in the pot.
• Plant kale on 8-inch (20cm) centers in large containers.
• Move kale grown in containers into the cool shade when the weather warms to extend the season.

Kale Pest and Disease

Kale is generally resistant to pests and diseases, but you should watch for common issues like aphids, cabbage worms, and flea beetles. Insecticidal soap or neem oil can be used for control. Cutworms, cabbage loopers, and imported cabbage worms can attack Kale. Control these pests by handpicking or spraying with Bacillus thuringiensis.

Kale diseases

Kale typically does not suffer from diseases. It can be infected with a soil-borne disease called clubroot. Plants will collapse and die. Diseased plants should be lifted and placed in the garbage, not the compost pile. Crop rotation can eventually eliminate this disease.

Kale harvest

Harvest kale any time after the plant has eight or more leaves. Simply trim or snap at the base, starting with the outermost leaves. You can start harvesting kale leaves when they reach a usable size, usually around 8-10 inches in length. Harvest the outer leaves first, allowing the inner leaves to continue growing. Regular harvesting encourages the plant to produce more leaves. Peak harvest time for kale is when the leaves are firm, crisp, and bright-colored. Young and just mature plants have the most tender leaves. Old leaves will lose their luster and become tough and bitter. You can harvest kale leaves as soon as they are big enough to eat or let them mature on the plant. Older outer leaves exposed to more sunlight will be rich in vitamin C and calcium.

Kale will be ready for harvest 55 days from transplanting and 70 to 80 days from seed. There are two ways to harvest kale; you can pick individual leaf rosettes for a cut-and-come-again crop, or cut the entire plant.

The tenderest leaves are those in the just-opening rosette at the top of the plant. Leaves on the uppermost part of the plant are more tender than those at the bottom.

Picking a few leaves at a time will encourage fresh growth and prolong the season. If you harvest the entire plant, cut 2 inches above the soil and the plant will sprout new leaves in 1 to 2 weeks. Delaying the kale harvest until after the first frost will greatly enhance the flavor.

Allowing Kale to Go To Seed

Allowing kale to go to seed is a natural part of its life cycle, but it typically happens in the plant's second year. When kale goes to seed, it bolts, producing a central flowering stalk.

How to prepare kale

Cool- and cold-weather kale can be served almost like summer-tender spinach: cut out the center ribs of young kale and use the leaves cut into strips as salad greens; dice the ribs and add them to the salad for a bit of crunch.

Cook kale leaves just out of the garden, only a few minutes longer than spinach. And in the dead of winter, cut frozen kale leaves from the plant and cook them before they thaw; the flavor will not suffer.