How to Grow Marrowstem Kale
Marrowstem Kale
Brassica oleracea var. acephala
vegetableMarrowstem kale is a robust, cold-hardy brassica featuring tall, sturdy stems with large, deeply lobed blue-green leaves. The thick, edible stems develop a marrow-like texture when cooked, making them as prized as the tender leaves. This heirloom variety is exceptionally nutritious and becomes sweeter after a light frost.
Looking for a specific variety?
When should you plant Marrowstem Kale 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 Marrowstem Kale timeline · Pittsburgh, PA (Zone 6b)
-
Plant Marrowstem Kale
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Marrowstem Kale
Around Jun 6≈ 50 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Marrowstem Kale dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; prefers cooler climates and tolerates hard freezes
Sign up free to see if Marrowstem Kale grows in your zone — and get a personalized planting timeline.
Get my Marrowstem Kale timeline →Growth Stages
Seedling
2-3 weeksTiny seedlings emerge with rounded cotyledons; first true leaves appear lobed and delicate
Thin crowded seedlings to proper spacing early. Keep soil moist but avoid waterlogging. Provide 12-16 hours of light daily if growing indoors.
Vegetative Growth
4-6 weeksPlant develops a strong central stem and increasingly larger, deeply lobed leaves arranged in a rosette pattern
Apply balanced fertilizer (10-10-10) every 3 weeks. Water deeply and consistently. Mulch around base to retain moisture and suppress weeds. Stake tall varieties if needed.
Stem Development
3-4 weeksThe main stem thickens considerably and becomes woody with a marrow-like interior; leaves continue expanding
Reduce nitrogen-heavy fertilizing; shift toward potassium and phosphorus to encourage stem robustness. Continue consistent watering. Light frost actually improves flavor.
Leaf Maturity
4-6 weeksLeaves reach full size and color; stems achieve maximum thickness; plant stands 24-36 inches tall
Begin selective harvesting of outer leaves. Stop fertilizing. Frost tolerance increases after this stage.
Harvest & Extended Harvest
4-12 weeks or until hard freezePlant is at peak eating quality; leaves remain tender and stems are at their most palatable; plant produces new leaves continuously
Harvest outer leaves regularly to encourage new growth. Remove any yellowed or damaged foliage. Can harvest through winter in milder zones.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Row covers until flowering begins; hand-pick caterpillars; Bt (Bacillus thuringiensis) spray; encourage parasitic wasps
-
Row covers on young plants; neem oil; diatomaceous earth dust; reflective mulches; avoid feeding plant stress
-
Strong water spray to dislodge; insecticidal soap; neem oil; encourage ladybugs and lacewings
-
and
Hand-pick; copper barriers; beer traps; encourage ground beetles; remove hiding spots
-
Improve air circulation; sulfur dust; milk spray (1 part milk to 9 parts water); remove infected leaves
Uses
Nutritious Greens & Edible Stems
CulinaryMarrowstem kale leaves are tender when young and can be eaten raw in salads or lightly sautéed. The stems are thick and succulent, with a mild cabbage-like flavor when steamed, roasted, or added to soups—resembling marrow in texture. [source]
Dense Nutritional Profile
MedicinalRich in vitamins K, C, A, and minerals including calcium, iron, and potassium. Contains glucosinolates and other phytonutrients with anti-inflammatory and potential cancer-preventive properties. [source]
Long-Term Storage & Preservation
HouseholdLeaves can be frozen, blanched, or dehydrated for winter storage. Kale chips are popular healthy snacks. The hardy plant extends harvest season deep into winter. [source]
Pollinator & Beneficial Insect Support
WildlifeIf allowed to flower (yellow kale flowers in late season), marrowstem kale attracts bees and parasitic wasps that prey on garden pests. The plant feeds beneficial ground beetles. [source]
Ornamental Garden Value
CraftMarrowstem kale's dramatic blue-green, deeply lobed leaves and tall structure make it visually striking in ornamental gardens. Cold-hardy foliage becomes even more colorful after frost. [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 plant is 12+ inches tall by snapping or cutting leaves at the base. Harvest regularly to encourage continuous production. Stems can be harvested by cutting the entire plant at soil level, or individual stem segments can be peeled and harvested while plant continues growing. Best flavor after a light frost (below 40°F). Continue harvesting through winter in zones 7+; in colder zones, harvest before hard freeze or use as a cool-season spring crop.
Fun Facts
- 🌱 Marrowstem kale is an heirloom variety with roots in European gardening traditions, prized for centuries for its uniquely tender, marrow-like stems that taste distinctly different from the leaves.
- 🌱 Kale becomes sweeter after exposure to frost because cold triggers the conversion of starches to sugars, acting as a natural antifreeze—making winter-harvested kale a gourmet delicacy.
- 🌱 A single mature marrowstem kale plant can produce leaves continuously for 3-4 months or longer in cool climates, with outer leaves harvested regularly while the plant keeps growing from the center.
Gardening Terms
New to gardening? Learn about terms used in this guide:
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Marrowstem Kale planting timeline
Tell us your zip code and we'll calculate exactly when to start Marrowstem Kale seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Marrowstem Kale timeline →