How to Grow Purple Choy Sum
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Purple Choy Sum
Brassica rapa subsp. parachinensis
vegetablePurple choy sum is an Asian leafy green vegetable characterized by slender, tender stems topped with small flowering buds and dark purple leaves. It has a mild, slightly sweet flavor and is prized in Asian cuisines for stir-frying and steaming. The entire plant—stems, leaves, and buds—is edible and nutritious.
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Example Purple Choy Sum timeline · Pittsburgh, PA (Zone 6b)
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Plant Purple Choy Sum
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 Purple Choy Sum
Around Jun 1≈ 45 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 5-9, but can be grown in zones 3-10 with attention to season timing
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Get my Purple Choy Sum timeline →Growth Stages
Seedling
7-10 daysTiny purple-tinged cotyledons emerge, followed by first true leaves with notched edges
Keep soil moist and warm (60-70°F). Thin seedlings to proper spacing when 2-3 inches tall. Provide bright light to prevent leggy growth.
Vegetative Growth
3-4 weeksPlant develops multiple slender stems with elongated purple leaves; no flowering yet
Maintain consistent moisture and steady cool temperatures (50-70°F). Apply balanced fertilizer every 2-3 weeks. Mulch around base to retain moisture and regulate temperature.
Budding
1-2 weeksSmall flower buds appear at stem tips, still surrounded by tight purple leaves; peak harvest stage
Increase watering as buds develop. Do not allow plants to dry out. Stems become most tender at this stage. Begin harvesting outer stems to encourage continued bud production.
Flowering
1-2 weeksYellow or purple flowers bloom from buds; leaves may coarsen and stems become slightly tougher
Harvest immediately if you want tender buds and stems. If allowing to flower, plants will set seed. Provide consistent water and continue fertilizing if continuing growth.
Seed Production
4-6 weeksPlant produces elongated seed pods on tall stalks; foliage becomes sparse and toughens considerably
If collecting seed, allow entire plant to mature. Otherwise, remove spent plants to prevent self-seeding. Seeds mature in 60-80 additional days after flowering begins.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Use row covers on young plants. Hand-pick caterpillars. Spray with Bt (Bacillus thuringiensis) if infestation occurs.
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Apply row covers or fine netting. Dust with food-grade diatomaceous earth. Use neem oil spray in severe cases.
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Spray with strong water stream to dislodge. Use insecticidal soap or neem oil. Introduce natural predators like ladybugs.
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Hand-pick in early morning or evening. Use beer traps. Create copper barriers. Apply slug pellets if necessary.
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Use yellow sticky traps. Spray with insecticidal soap. Ensure good air circulation and avoid overwatering foliage.
Uses
Stir-frying and Asian cooking
CulinaryPurple choy sum is a staple in Cantonese and Southeast Asian cuisines, where it is lightly stir-fried with garlic and oil to preserve the tender texture and mild sweetness of stems and buds. The entire plant is eaten and develops a delicate flavor when cooked briefly over high heat. [source]
Fresh salads and raw preparations
CulinaryYoung, tender choy sum stems and buds can be eaten raw in salads, providing a mild, slightly mustard-like flavor and crispy texture. They pair well with vinaigrettes and light dressings. [source]
Nutritional and anti-inflammatory properties
MedicinalPurple choy sum is rich in vitamins A, C, and K, along with glucosinolates—sulfur compounds known for anti-inflammatory and potential cancer-preventive properties. The purple pigmentation indicates anthocyanin content, a powerful antioxidant. [source]
Quick-cooking weeknight vegetable
HouseholdWith a days-to-maturity of 45-60, purple choy sum offers home gardeners a fast return on investment, making it ideal for succession planting throughout the growing season for continuous fresh harvests. [source]
Pollinator and beneficial insect attraction
WildlifeIf allowed to flower, purple choy sum attracts bees, hoverflies, and other beneficial pollinators to the garden while providing early season nectar sources. [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 45-60 days after planting when flower buds are tight and stems are tender, typically 6-10 inches tall. Cut the entire flowering stem at the base with a sharp knife, or harvest outer stems first to encourage continued growth and budding. Morning harvest yields the crispest, most tender stems. For maximum tenderness, harvest before flowers open. Regular harvesting extends production for 2-4 weeks. In warm climates, grow as a cool-season crop (fall through spring). In temperate zones, plant in spring for early summer harvest or in late summer for fall harvest to avoid summer bolting.
Fun Facts
- 🌱 Purple choy sum is also called 'Chinese broccoli' or 'gai lan' in Cantonese, though it is distinct from actual broccoli; it is a brassica more closely related to bok choy and cabbage.
- 🌱 The purple pigmentation comes from anthocyanins, the same antioxidants found in blueberries and purple cabbage, making it a nutritional powerhouse with visual appeal.
- 🌱 In traditional Asian markets, choy sum is often sold with the flowers still on the stems, indicating peak freshness and optimal eating quality—a sign home growers can watch for when harvesting.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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