Growing Chinese broccoli: seeds, conditions and harvesting

Chinese broccoli, also known as gai lan or Chinese kale, is a fast-growing leafy green with thick, crisp stems, broad blue-green leaves, and small edible flower buds. It tastes like a cross between broccoli and kale, with a pleasant bitterness that mellows when cooked. You can harvest it about 60–70 days after sowing, cutting the central stem just as the flower buds appear for the most tender leaves and stalks.

What is Chinese broccoli (gai lan)?

Chinese broccoli is a cool-season vegetable in the Brassicaceae family, closely related to broccoli, kale, and cabbage. Unlike heading broccoli, which produces one large central head, gai lan is grown for its edible stems and leaves and loose flower buds. The plant stands upright, 30–40 cm tall, with smooth, glaucous (slightly waxy) leaves that are thick and succulent. The main stem is firm and crisp, somewhat like asparagus but with a broccoli flavor. If you let the buds open, they reveal small white or yellow flowers, but the best eating quality comes from cutting before they fully bloom.

Chinese broccoli growing conditions

Gai lan thrives in cool weather between 15°C and 22°C (60–72°F). It can tolerate light frost, which may even improve flavor by increasing sugars in the leaves. In hot weather above 27°C (80°F), plants bolt quickly, producing thin, bitter stems and smaller leaves. Plant in full sun to part shade; in warmer climates, afternoon shade helps delay bolting. The soil should be fertile, well-drained, and rich in organic matter, with a pH between 6.0 and 7.0. Consistent moisture is key: keep the soil evenly moist but not waterlogged, providing about 2.5 cm (1 inch) of water per week.

Chinese broccoli growing season

The planting season depends on your climate:

• Temperate regions: Sow seeds in late summer to early autumn for a fall/winter crop, or in early spring for a late spring harvest. Fall plantings often produce the most tender leaves because the weather cools as the plants mature.
• Subtropical/tropical regions: Grow gai lan during the coolest months, typically late autumn through early spring. It struggles in summer heat and humidity.

Because gai lan matures quickly, you can make successive sowings every 2–3 weeks during the growing season for a continuous supply.

How to grow Chinese broccoli from seeds

Follow these steps for successful seed sowing:

1. Prepare the bed: Loosen the soil to 20–25 cm deep, mix in 5–8 cm of compost or well-rotted manure, and rake smooth. If your soil is heavy clay, add sand or perlite to improve drainage.
2. Sow seeds: Direct sow seeds 1 cm deep, spacing them 5 cm apart in rows 30 cm apart. Or start indoors 4–6 weeks before your last frost date, then transplant seedlings when they have 3–4 true leaves.
3. Thin seedlings: Once direct-sown seedlings are 5 cm tall, thin to 15–20 cm apart. Use the thinnings in stir-fries or salads.
4. Water gently: Keep the seedbed consistently moist; use a fine spray to avoid washing away seeds. Seedlings emerge in 5–10 days at temperatures between 15–25°C.
5. Mulch: Apply a 5 cm layer of straw or shredded leaves around plants to retain moisture and keep roots cool.

During growth, feed every 3–4 weeks with a balanced liquid fertilizer (e.g., fish emulsion or seaweed extract) to encourage lush leaf and stem growth. Watch for common pests like aphids, flea beetles, and cabbage worms; use row covers or organic insecticidal soap as needed.

Harvesting Chinese broccoli

Knowing when and how to harvest gai lan ensures tender, flavorful stems and leaves. The ideal harvest timing is when the central flower stalk is 15–20 cm tall and the flower buds are just beginning to form but are still tightly closed. At this stage, usually 60–70 days after sowing, the stems are crisp and tender, and the leaves have a balanced flavor.

• Cut the main stem with a sharp knife or scissors, 5–10 cm above the soil, leaving a few lower leaves on the remaining plant. This encourages side shoots to develop for a second, smaller harvest in 3–4 weeks.
• Harvest side shoots when they are 10–15 cm long, with a few leaves and small buds. Regular cutting keeps the plant productive for 4–6 weeks total.
• Do not wait until flowers fully open: once they open, the stems become woody and the leaves turn bitter. If you miss the window, you can still eat the leaves and stems, but they will be tougher and need longer cooking.

After harvesting, use gai lan fresh within a few days. Store it in a plastic bag in the refrigerator crisper; it stays crisp for up to 5 days. To prepare, wash thoroughly, trim any tough stem ends, and cut into 5–7 cm sections. Stir-fry with garlic and oyster sauce, or blanch and serve with a drizzle of soy sauce and sesame oil. It can substitute for broccoli in most recipes but has a softer texture and stronger flavor.

Comparison with similar vegetables

Compared to broccoli, gai lan has thinner stems, more leafy greens, and a slightly more assertive taste. It is more tolerant of heat than kale but less cold-hardy. Both kale and gai lan offer edible leaves, but gai lan's succulent stems set it apart.