How to Grow Thorogreen
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Thorogreen
Brassica oleracea var. acephala
vegetableThorogreen is a non-heading kale variety known for its deeply frilled, dark green leaves and exceptional cold hardiness. It produces tender, nutritious greens that improve in flavor after frost exposure. This open-pollinated cultivar is prized by gardeners for its productivity and culinary versatility.
When should you plant Thorogreen in your zone?
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Example Thorogreen timeline · Pittsburgh, PA (Zone 6b)
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Plant Thorogreen
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Thorogreen
Around Jun 11≈ 55 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Thorogreen dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; excellent cold tolerance makes it ideal for northern gardens
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Get my Thorogreen timeline →Growth Stages
Seedling
10-14 daysTiny cotyledons emerge, followed by first true leaves with slight serration
Keep soil consistently moist. Maintain 60-70°F for germination. Thin seedlings to prevent crowding.
Vegetative Growth
30-45 daysPlant develops multiple deeply lobed leaves; stem elongates slowly. Leaves darken to blue-green color.
Transplant outdoors when 4-6 true leaves develop. Water deeply and fertilize with nitrogen-rich fertilizer every 2-3 weeks. Mulch around base.
Full Rosette Formation
20-30 daysPlant reaches mature size with dense crown of heavily frilled, curly leaves spreading 18-24 inches wide
Continue regular watering and feeding. Monitor for pests. Leaves become sweeter and more tender as plant matures.
Continuous Harvest
60-90 daysLower leaves mature and become harvest-ready while plant continues producing new growth from center
Begin harvesting outer leaves when 8-10 inches long. Remove yellowed or damaged leaves. Plant remains productive for 3-4 months.
Cold Hardening
2-4 weeks after first frostAfter frost exposure, sugars accumulate in leaves, increasing sweetness and improving flavor profile
Allow light frosts (28-32°F) to enhance flavor. Plant can withstand temperatures down to 0°F. Continue harvesting through winter in mild climates.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Use row covers on young plants; apply Bt (Bacillus thuringiensis); handpick caterpillars; plant nasturtiums as trap crop
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Spray strong water stream; use insecticidal soap; introduce ladybugs; neem oil if severe
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Use row covers; apply neem oil; dust with food-grade diatomaceous earth; plant trap crops of radishes
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Hand-remove; apply Bt; encourage parasitic wasps; reflective mulches deter adults
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Increase humidity through misting; spray neem oil; encourage natural predators like phytoseiid mites
Uses
Nutritious Leafy Green
CulinaryThorogreen kale is packed with vitamins A, C, K, and minerals like iron and calcium. Use raw in salads when young and tender, or sauté, steam, or add to smoothies and soups. [source]
Kale Chips & Crispy Preparations
CulinaryThe deeply frilled leaves are ideal for making crispy kale chips by tossing with oil and salt, then roasting. The texture becomes wonderfully crunchy while maintaining nutrient density. [source]
Glucosinolate-Rich Superfood
MedicinalThorogreen contains glucosinolates, sulfur-containing compounds that research suggests may have anti-inflammatory and chemopreventive properties. Regular consumption is associated with various health benefits. [source]
Natural Ornamental Garden Accent
HouseholdThe striking deeply frilled blue-green leaves make Thorogreen an attractive addition to ornamental gardens and landscape beds. It provides visual interest while remaining fully edible. [source]
Pollinator & Beneficial Insect Support
WildlifeWhen allowed to bolt, kale produces attractive yellow flowers that attract bees and other pollinators. Left in the garden, it provides late-season forage for beneficial insects. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Begin harvesting when outer leaves reach 8-10 inches long, typically 55-75 days after transplanting. Pinch or cut leaves from the bottom and sides, leaving the central growing point intact for continued production. Harvest in the morning after dew dries for best flavor and texture. Regular harvesting encourages more leaf production. Plant produces for 3-4 months under ideal conditions. Leaves are sweetest after light frost. For baby kale, harvest at 4-6 inches; for full-size leaves, wait until 10-12 inches.
Fun Facts
- 🌱 Thorogreen is an heirloom open-pollinated kale variety that has been cultivated for generations, allowing gardeners to save seeds from their best plants for future seasons.
- 🌱 Kale's flavor actually improves after frost exposure due to conversion of starches to sugars—a natural antifreeze mechanism that makes Thorogreen sweeter in fall and winter.
- 🌱 Thorogreen kale can produce leaves for 3-4 consecutive months from a single planting, making it one of the most productive vegetables per plant in a home garden.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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