Yu Choy Sum Seeds | Brassica rapa | Late Green Flowering Brassica | Cantonese Classic | Downy Mildew Tolerant | 45–55 Days

Yu Choy Sum Seeds – Brassica rapa | Late Green Flowering Brassica | Cantonese Classic

Yu Choy Sum (Late Green) (Brassica rapa var. parachinensis) is one of the most popular and productive flowering brassicas in Cantonese cuisine — a late-maturing, slow-bolting variety with dark green leaves, exceptional versatility at harvest, and good tolerance to both Downy Mildew and cold weather. Harvest the entire plant as Yu Choy (stems and leaves) before the buds open, or wait for tender flower buds and harvest as Yu Choy Sum — the flower buds and stems are a true delicacy, sweet and mild, prized across southern Chinese and Southeast Asian cuisines. Summer and fall plantings produce thicker, more substantial stems. Warm-season annual; matures in 45–55 days.

Variety Details

• Botanical Name: Brassica rapa var. parachinensis
• Common Names: Yu Choy Sum, Choy Sum, Flowering Chinese Cabbage, You Cai
• Type: Late-maturing, slow-bolting flowering brassica
• Disease tolerance: Downy Mildew tolerant
• Cold tolerance: Good; sensitive to temperatures below 50–55°F (may bolt)
• Days to maturity: 45–55 days
• Optimal growing temperature: 60–80°F
• Approx. seed counts: ~6,100/oz • ~24,400/4 oz • ~97,600/lb

Culinary Uses

• Classic Cantonese preparation: Steam or blanch lightly and drizzle with oyster sauce — simple, elegant, and traditional
• Stir-fried with garlic and ginger — the most common home-cooking preparation across southern Chinese cuisines
• Cantonese soups — added whole or chopped to clear broths and noodle soups
• Dim sum side dish — steamed choy sum with soy and sesame
• Quick-pickled stems in rice vinegar and chili
• Sautéed with fermented tofu, black bean sauce, or XO sauce for bold umami depth
• Flower buds are the most prized part — harvest just before they fully open for sweetest flavor

Planting Guide

• Best timing: Late summer to fall for best flavor and stem quality. Can be planted in spring in some regions once the risk of hard frost has passed.
• Temperature: Optimal growth at 60–80°F. Sensitive to temperatures below 50–55°F, which may trigger premature bolting.
• Soil: Fertile, well-draining. Keep consistently moist throughout the growing period.
• Fertilizing: Feed regularly for vigorous stem and leaf growth.

Harvesting

• Main stalk: Harvest when the plant reaches 10–14 inches tall and just before the flower buds open. Cut the main stalk cleanly — the plant then branches freely, producing multiple side shoots for an extended continuous harvest.
• Yu Choy (stem & leaf): Harvest before buds open for the largest stems and leaves.
• Yu Choy Sum (stem, leaf & flower buds): Allow buds to develop but harvest just before flowers open for the sweetest, most delicate flavor.
• Harvest in the morning for best texture and moisture retention.