How to Grow Rubens Kale
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Rubens Kale
Brassica oleracea var. acephala
vegetableRubens is a curly kale cultivar known for its deeply frilled, dark green leaves and exceptional cold hardiness. This heirloom variety is prized for both culinary use and ornamental appeal, with a sweet flavor that improves after frost. It's a nutrient-dense leafy green that thrives in cool-season gardening.
When should you plant Rubens Kale in your zone?
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Example Rubens Kale timeline · Pittsburgh, PA (Zone 6b)
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Plant Rubens Kale
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 Rubens Kale
Around Jun 11≈ 55 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Rubens Kale dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 2-9; best in cooler regions (zones 3-7)
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Seedling
2-3 weeksSmall, smooth leaves with 2-4 true leaves visible; pale to medium green color.
Keep soil consistently moist but not waterlogged. Provide 12-16 hours of light daily. Thin seedlings to 2-3 inches apart if direct seeding.
Vegetative Growth
3-4 weeksRosette forms with increasingly frilled, curled leaves; deep green coloration develops.
Maintain consistent watering and fertilize every 2-3 weeks with balanced or nitrogen-heavy fertilizer. Mulch around plants to retain moisture and suppress weeds.
Leaf Development
3-4 weeksMature, deeply ruffled dark green leaves form in tight rosette; plant reaches full size and density.
Continue regular watering and monthly fertilization. Begin harvesting outer leaves once plant is 8-10 inches tall. Maintain consistent moisture for tender leaves.
Mature Harvest Ready
4-8 weeks or until end of seasonFull-sized plant with abundant, densely curled leaves; flavor sweetens after light frost.
Cold improves sweetness and texture. Harvest regularly to encourage new leaf production. Remove any yellowing or damaged lower leaves.
Extended Season
6-12 weeks depending on climatePlant continues producing leaves through fall and early winter; extreme cold hardens leaves further.
Rubens tolerates temperatures to -10°F. Provide row covers or cold frames in harsh winter zones. Continue light harvesting if plant remains viable.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Use row covers on young plants; apply Bacillus thuringiensis (Bt) spray; handpick caterpillars; encourage natural predators like parasitic wasps.
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Apply Bt spray; use netting; handpick; plant trap crops like nasturtium nearby.
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Use reflective mulches; apply kaolin clay spray; encourage beneficial insects; rotate crops annually.
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Spray with strong water stream; apply insecticidal soap; use neem oil; introduce ladybugs and lacewings.
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Handpick and destroy eggs/bugs; use reflective mulch; plant trap crops; apply neem oil as needed.
Uses
Nutritious Leafy Green
CulinaryRubens kale is excellent fresh in salads, smoothies, or as a cooked side dish. Its tender leaves and sweet flavor make it more palatable than some other kale varieties, especially after frost exposure. [source]
Chips and Crisps
CulinaryThe curly leaves are ideal for making homemade kale chips through roasting with oil and seasonings, creating a healthy snack alternative to potato chips. [source]
Nutritional Supplement
MedicinalRubens kale is exceptionally nutrient-dense, providing vitamin K, vitamin C, calcium, iron, and antioxidants. Traditionally used to support immune function and bone health. [source]
Garden Decoration
OrnamentalThe deeply frilled, dark green foliage is attractive in ornamental gardens, borders, and containers. Often used in winter arrangements for its texture and color retention. [source]
Long-Term Storage
HouseholdRubens kale keeps well in the refrigerator for 5-7 days and can be blanched and frozen for longer storage, making it ideal for season extension. [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 reaches 8-10 inches tall; pick lower, older leaves first to encourage new growth. Harvest in morning for best flavor and texture. Continue harvesting throughout season; flavor improves after light frost (around 20-32°F). For baby leaf kale, harvest at 30-40 days when leaves are 4-6 inches long. Cut or gently pinch leaves rather than pulling to avoid damaging central growing point.
Fun Facts
- 🌱 Rubens kale's flavor becomes noticeably sweeter and milder after exposure to frost, as the plant converts starches to sugars as a natural antifreeze mechanism.
- 🌱 Unlike many vegetables, kale is technically a leaf and not a head; Rubens is a 'non-heading' kale variety that continuously produces new leaves from the central stem.
- 🌱 Rubens is an heirloom variety that originated in European gardens and has been cultivated for centuries, prized for both its hardiness and culinary excellence in cool-season regions.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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