How to Grow Kale
Brassica oleracea var. sabellica
Kale is a robust, nutrient-rich leafy green that thrives in cooler climates, making it an excellent choice for extending your growing season. Its hardiness and versatility in the kitchen make it a must-have for any home gardener.
soil preparation
Kale prefers a well-drained, loamy soil with a pH range of 6.0 to 7.5. To prepare the soil, start by testing the pH and adjusting if necessary using lime to raise the pH or sulfur to lower it. Incorporate a generous amount of organic matter such as compost or well-rotted manure into the soil to improve fertility and drainage. Aim for at least 2 inches of compost spread over the planting area and tilled to a depth of 6 to 8 inches. Ensure the bed is level and free of large clumps or debris.
planting steps
Choose the Right Variety
Select a variety that suits your climate and preferences. Scotch kale is widely grown for its robust flavor, while blue kale is hardier and better suited for late plantings. For home gardeners, starting seeds indoors about 4 to 6 weeks before the last frost can give you a head start.
Tip: Use seed trays with individual cells to minimize root disturbance when transplanting.
Prepare the Seedbed
If planting directly in the garden, prepare the seedbed by ensuring it is well-drained and free of weeds. Create rows that are 18 to 24 inches apart using a hoe or garden rake. Mark the rows with stakes and string for precision.
Tip: Water the soil thoroughly before planting to ensure good seed-to-soil contact.
Sow the Seeds
Plant kale seeds at a depth of 1/4 to 1/2 inch. Space the seeds about 6 inches apart within the rows. Cover the seeds with soil and gently firm the soil over them.
Tip: Use a fine spray setting on your watering can or hose to avoid washing away the seeds.
Thinning Seedlings
Once the seedlings have emerged and developed their second set of true leaves, thin them to a final spacing of 18 to 24 inches apart. This will ensure each plant has enough space to grow without competing for nutrients.
Tip: Use scissors to cut the excess seedlings at soil level to avoid disturbing the roots of the remaining plants.
Transplanting (if applicable)
If you started seeds indoors, transplant them into the garden when they have at least two sets of true leaves and are about 4 to 6 inches tall. Dig a hole slightly larger than the root ball and place the plant in the hole, burying it up to the first set of true leaves. Water thoroughly after planting.
Tip: Hardening off seedlings by gradually exposing them to outdoor conditions over a week can help prevent transplant shock.
watering
Kale requires consistent moisture, especially during the growing season. Aim for 1 to 1.5 inches of water per week, either from rainfall or irrigation. Water deeply once or twice a week rather than shallowly every day to encourage deep root growth. Use soaker hoses or drip irrigation to deliver water directly to the soil and minimize leaf wetness, which can reduce the risk of fungal diseases. Signs of overwatering include yellowing leaves and wilting, while underwatering may cause the leaves to become tough and bitter.
feeding & fertilizer
Kale is a heavy feeder and benefits from regular fertilization. At planting, incorporate a balanced fertilizer with an NPK ratio of 10-10-10 into the soil at a rate of 1 pound per 100 square feet. During the growing season, side-dress the plants with a nitrogen-rich fertilizer such as fish emulsion or blood meal every 4 to 6 weeks. Apply the fertilizer along the sides of the rows and water it in thoroughly.
pruning & training
Kale does not require extensive pruning, but you can encourage bushier growth by pinching off the top set of leaves when the plants are about 12 inches tall. This will stimulate lateral bud development and result in a more compact plant. Remove any yellow or damaged leaves to prevent disease and improve air circulation.
harvesting
Kale is ready to harvest when the leaves are full-sized but still tender, typically 65 to 75 days after planting. Look for leaves that are about 8 to 10 inches long. Harvest by cutting the outer leaves at the base of the plant with a sharp knife or scissors, leaving the inner leaves to continue growing. For succession harvesting, sow new seeds every 2 to 3 weeks throughout the growing season to ensure a continuous supply of fresh kale.
storage & preservation
After harvest, rinse the kale leaves in cool water and pat them dry with a clean towel. Store the leaves in a plastic bag or container with a damp paper towel to maintain humidity. Place the container in the refrigerator, where the kale will stay fresh for up to 5 days. For longer storage, blanch the leaves by immersing them in boiling water for 2 minutes, then immediately transferring them to an ice bath. Drain and pack the blanched leaves into freezer bags or containers, removing as much air as possible before freezing.
common mistakes to avoid
- ✗Overwatering: Kale prefers well-drained soil. Ensure the soil is not waterlogged, which can lead to root rot. Water deeply but infrequently to encourage deep roots.
- ✗Underfertilizing: Kale is a heavy feeder and requires regular fertilization. Use a balanced fertilizer at planting and side-dress with nitrogen-rich fertilizer during the growing season to promote healthy growth.
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