Curly Kale
Brassica oleracea var. sabellica
Family: Brassicaceae
Curly kale is the most common kale variety, with tightly ruffled blue-green leaves and a bold, slightly bitter flavor. Extremely cold-hardy and productive, it becomes sweeter after frost. Perfect for kale chips, smoothies, and sautéing.
Days to Harvest
50-65 days
Sun Needs
Full Sun to Partial Shade (4-6 hours)
moderate
Germination Temp
70°F optimal
Start Indoors
6 weeks before last frost
Germination
4-10 days
Seed Depth
1/4 to 1/2 inch
Light to Germinate
No
💡 Tip: Direct sow in late summer for fall/winter harvest. Flavor dramatically improves after frost.
Soil Type
Rich, well-draining soil with organic matter
pH Range
6 - 7.5
Spacing
18-24 inches between plants, 24-30 inches between rows
⚠️ Avoid planting near:
History
Curly kale has been grown for centuries as a cold-hardy winter vegetable. It was a staple in European peasant gardens due to its ability to survive harsh winters and provide nutrition when other greens weren't available.
Nutritional Benefits
- ✓One of the most nutrient-dense foods
- ✓Extremely high in Vitamin K
- ✓Excellent source of Vitamins A and C
Optimal Growing Temp
55°F - 75°F
Curly kale thrives in cool weather (55-75°F) but is extremely cold-hardy. Flavor improves dramatically after frost. Can survive temperatures down to 10°F. Tolerates heat but leaves may become tough.
Survival Range
10°F - 85°F
Can survive these temperatures
Frost Note: One of the most cold-hardy vegetables. Survives hard frost (10-20°F) and even snow. Frost converts starches to sugars, making leaves sweeter. Can be harvested through winter in many climates.
Best USDA Zones
Humidity
40-60%
Moderate humidity preferred. Good air circulation prevents fungal diseases among curly leaves.
Height
18-24 inches
Spread
18-24 inches
Growth Habit
upright
Germination
4-10 days
Seeds germinate in cool soil (45-85°F). Direct sow or start indoors.
Seedling Stage
Duration: 3-4 weeks
True leaves: Develop strong seedlings before transplanting. True leaves show characteristic curl.
Transplant ready: Ready when 4-5 inches tall with 4-5 true curly leaves.
Vegetative Growth
Duration: 6-8 weeks
Rapid leaf production. Begin harvesting outer leaves at 8-10 inches.
Harvest Maturity
Timing: 55-65 days from seed
- Full-sized plant ready for continuous harvest
- Continues producing through frost
Per Plant
2-4 lbs of leaves over season
Per Square Foot
1-2 lbs at 18-inch spacing
Harvest Frequency
Harvest outer leaves every 1-2 weeks
Factors Affecting Yield
- •Cold tolerance extends harvest
- •Regular picking promotes growth
- •Frost sweetens flavor
- •Soil fertility
Seedling Stage
Keep consistently moist during establishment
Established Plants
Deep watering every 4-7 days, 1-1.5 inches per week
Preferred Method
Water deeply at soil level. Soaker hose ideal for keeping curly leaves dry.
⚠️ Critical Watering Periods
- • Transplant establishment
- • Hot summer weather
- • Active growth phases
Pro Tips
- Consistent moisture prevents tough, bitter leaves
- Mulch heavily to retain moisture and moderate temperature
- Water needs decrease as temperatures cool in fall
- Drought stress intensifies bitterness
Feeding Schedule
Organic Options
Top-dress with compost monthly. Apply liquid feed every 3-4 weeks.
Minimum Size
12 inch pot minimum
Recommended Size
14-16 inch pot
Depth Required
12 inches minimum
Best Varieties for Containers
Container Tips
- Choose compact varieties like Dwarf Blue Curled for containers
- Deep containers provide stability for tall plants
- Water regularly—kale is thirsty
- Feed monthly with balanced fertilizer
- Can overwinter containers in sheltered locations
Why Prune
When
Begin harvesting when outer leaves reach 8-10 inches
How Often
Every 1-2 weeks throughout growing season
Technique
Snap or cut outer leaves at base, leaving inner leaves to continue growing
Remove
- ✗ Outer mature leaves
- ✗ Yellowed or damaged leaves
- ✗ Flower stalks if bolting
Keep
- ✓ Growing center
- ✓ Young inner leaves
- ✓ At least 4-5 center leaves
Plant Every
Spring and late summer plantings
Sowings/Season
2 main plantings
Duration
Plant spring for early harvest, late summer for fall/winter
Tips
- Spring planting: 6-8 weeks before last frost for summer harvest
- Late summer planting: 10-12 weeks before first frost for fall/winter harvest
- Fall plantings are sweetest due to frost exposure
- Single plants produce continuously for months
