How to Grow Imperial Green
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Imperial Green
Brassica oleracea var. acephala
vegetableImperial Green is a cold-hardy, curly-leafed kale variety prized for its deep green color, tender texture, and slightly sweet flavor. It grows as a leafy green without forming a head and becomes sweeter after frost exposure. This heirloom variety is highly nutritious and productive, producing harvestable leaves continuously throughout the season.
When should you plant Imperial Green in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Imperial Green timeline · Pittsburgh, PA (Zone 6b)
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Plant Imperial Green
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 Imperial Green
Around Jun 6≈ 50 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Imperial Green dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9, with best flavor in cooler zones (3-7)
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Seedling
2-3 weeksTiny leaves emerge with characteristic kale texture. Plants are delicate with 2-4 true leaves visible.
Keep soil moist. Provide bright light if growing indoors. Thin seedlings to proper spacing. Protect from slugs and birds.
Vegetative Growth
3-4 weeksPlant develops multiple deeply-curled leaves on a central stem. Leaf count increases weekly with rich green coloration developing.
Maintain consistent moisture and fertility. Apply balanced fertilizer every 3-4 weeks. Mulch to retain moisture and suppress weeds. Monitor for pests.
Leaf Development & Early Harvest
2-3 weeksLower leaves reach harvestable size (6-8 inches) and become tender. Plant continues producing new leaves from the top.
Begin harvesting outer leaves when 6-8 inches long. This encourages more leaf production. Continue regular watering and feeding.
Peak Production
4-8 weeksPlant is tall and bushy with abundant curly leaves. Regular harvesting encourages continuous leaf production.
Harvest outer leaves regularly (every 7-10 days) to maintain productivity. Pinch off any flower shoots that form to direct energy to leaves. Continue consistent watering.
Fall Hardening & Enhanced Flavor
Until hard freezeFrost exposure converts starches to sugars, making leaves sweeter. Plant becomes more cold-hardy and flavor improves significantly.
Light frost (28-32°F) improves flavor—do not harvest after heavy frost below 20°F. Continue harvesting outer leaves. Plant can overwinter in mild zones.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick caterpillars daily. Use row covers before butterflies appear. Apply Bacillus thuringiensis (Bt) spray. Plant brassicas near nasturtiums as trap crops.
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Spray with strong water jet to dislodge. Use insecticidal soap or neem oil. Introduce ladybugs and parasitic wasps. Plant mint and garlic nearby.
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Handpick at night. Create barriers with copper tape or diatomaceous earth. Set beer traps. Encourage beneficial ground beetles.
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Use row covers on seedlings. Dust with food-grade diatomaceous earth. Apply neem oil spray. Plant radishes as trap crops.
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Hand-pick larvae. Use Bt spray. Install row covers. Attract parasitic wasps with alyssum and dill.
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Spray undersides of leaves with insecticidal soap or horticultural oil. Use yellow sticky traps. Introduce beneficial insects.
Uses
Nutritious Leafy Green
CulinaryImperial Green is excellent raw in salads, blended into smoothies, or massaged with olive oil to reduce bitterness. Cooking mellows the flavor; use in soups, stir-fries, sautés, or as a side dish. Sweeter after frost exposure. [source]
Glucosinolate-Rich Health Food
MedicinalKale contains glucosinolates, compounds that may have anti-cancer and anti-inflammatory properties. Rich in vitamins K, A, and C, and minerals like calcium and iron. Often recommended as a superfood for immune and bone health. [source]
Kale Chips & Dried Preparations
CulinaryLeaves can be dried and crisped into healthy snack chips by tossing with oil and baking. Also excellent for making mineral-rich kale powder for smoothies and wellness drinks. [source]
Natural Colorant & Dye
HouseholdThe deep green color can be extracted and used as a natural plant-based dye for fabrics and paper crafts. The purple/reddish tones in frost-exposed leaves offer additional color possibilities. [source]
Pollinator & Beneficial Insect Support
WildlifeIf allowed to flower (by letting some plants bolt in spring), Imperial Green provides pollen and nectar for bees and beneficial insects. Flowering plants attract parasitic wasps that control pest 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 outer leaves when they reach 6-8 inches long (around 40-50 days from planting). Pinch or cut leaves from the bottom and sides of the plant, leaving the central crown to continue producing. Regular harvesting encourages bushier growth and continuous leaf production. Harvest in the morning after dew dries for best flavor and texture. Imperial Green becomes noticeably sweeter after the first frost. Can be harvested continuously until a hard freeze (below 20°F). In mild climates, plants can overwinter and produce again in spring.
Fun Facts
- 🌱 Imperial Green kale becomes sweeter after exposure to frost because the plant converts starches to sugars as a natural antifreeze mechanism to protect its cells from freezing damage.
- 🌱 Kale is one of the most nutrient-dense foods available per calorie, containing more calcium per calorie than milk and more iron per calorie than beef—making it a superstar of the vegetable world.
- 🌱 The deeply curled leaves of Imperial Green provide maximum surface area for photosynthesis and make them particularly appealing for ornamental gardening, often grown in decorative vegetable displays and as edible landscape plants.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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