How to Grow Kale and Collards
A tip sheet on how to grow and care for kale and collards.
Kale and Collards
- Family: Brassicaceae (Mustard)
- Season: Cool
- Ease of growing: Easy
- Nutrient needs: High
- Water needs: High
- Common propagation: Seed
- Germination temperatures: 40°F to 100°F
- Germination time: 6 to 10 days
- Viability: 4 to 6 years
- Direct sow: April to August (collards); mid-June to August (kale)
- Weeks to grow transplants: 4 to 6
- Start: March to July
- Plant out: April to August
- Typical spacing: 8” x 24”
- Square foot per plant: 1
- Time to Harvest: baby kale, 25 days; mature, 60 to 150 days
Both kale and collards are considered non-heading cabbages. Kale comes in three types: Scotch, which has tightly curled leaves; Siberian, or types that are smooth with frilled edges; and Bicolor, which is used as an ornamental but is also edible. Red Russian is a Siberian type with tender leaves good for baby salad greens. Winterbor is a Scotch type that is more winter hardy and productive. Collard leaves always have smooth edges. There isn’t as large a diversity of varieties as kale.
Preparation and planting
For an early crop, sow in the spring once the soil has thawed. Good succession crops include peas, potatoes or beans. Kale or collards can also be planted in July or August and be held in the garden well into winter. In mild winters they can overwinter, providing tender leaves in early spring but tend to flower by late spring. For small salad leaves, grow plants close together (25 to 50 seeds per foot). Kale and collards prefer damp, not soggy, soil and for maximum production they need 1 to 1.5 inches of water per week. They are heavy feeders and benefit from side-dressing with a nitrogen-rich fertilizer when they reach a height of 4 to 5 inches. It’s also beneficial to mulch after plants are established. When frost is expected, pull earth up around the stem up to the basal leaves and mulch thickly. Frost will only improve the flavor.
Insects: Aphids, flea-beetles, cabbage maggots, imported cabbage worm, cabbage loopers, diamondback moth
Diseases: Damping off, black rot, downy mildew, anthracnose
Harvesting and storage
Harvest by picking individual leaves or cutting the entire plant. The peak time for harvest is when the leaves are firm, crisp and bright green. New leaves are the tenderest and add zest to salads. Cook larger leaves or add them to soups. Kale is an excellent source of vitamin A and has twice as much vitamin C as orange juice and more calcium than milk.
Developed by James Manning, Undergraduate Research Assistant, and Daniel Brainard, Vegetable Extension Specialist; MSU Department of Horticulture; Gary Heilig, MSU Extension educator.