Choy Sum
Brassica rapa var. parachinensis
vegetableChoy sum (Brassica rapa var. parachinensis), also widely sold as yu choy, is a fast Chinese flowering cabbage grown for its mild, sweet leaves, crisp stems, and small yellow flower buds, all harvested and cooked together at the bud stage. A cool-season green, it is ready in just 30 to 50 days and often regrows for a second cutting after the main stem is cut. It is a stir-fry staple with a clean, slightly sweet cabbage flavor, also good steamed or in soups. Plants stand about 8 to 16 in tall.
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Sun
full sun to partial shade
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Water
Every 4 days
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Harvest
~45 days
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Difficulty
easy
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Lifecycle
annual
One season, then done
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Spacing
8-12 in apart
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Planting Depth
Sow 0.25 in deep
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Soil pH
6.0-7.0
Growing Details
Soil Type
Fertile, moist, well-drained
Hardiness Zones
Zones 2 – 11
Grown as an annual. This range is its winter hardiness, but you can grow it for a single season in any zone.
When to Fertilize
Feed with nitrogen as growth begins
Fertilizer
Balanced fertilizer or compost; nitrogen for leafy growth
🌱 Growing Guide
Grow choy sum in full sun to partial shade in fertile, moist, well-drained soil with a pH around 6 to 7; it is prone to bolting in heat, so grow it in the cool of spring and fall. Direct sow 0.25 in deep and thin to about 8 to 12 in apart in rows roughly 11 in apart. Keep the soil consistently moist, since steady growth gives the most tender stems and delays bolting, but avoid waterlogging, which invites soft rot. Succession sow every couple of weeks for a continuous supply. It is a quick, easy crop that crops well in spring and again in autumn.
Planting Calendar
Sign in to personalize →spring planting
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Direct sow
Apr 1
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Projected first harvest
May 16
fall planting
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Direct sow
Aug 25
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Projected first harvest
Oct 9
JJan
FFeb
MMar
AApr
MMay
JJun
JJul
AAug
SSep
✅ Plant alongside
Good neighbors that attract beneficial insects or deter pests
- Carrot: Uses different root space and makes efficient use of the bed
- Beet: A cool-season companion with complementary needs
- Onion: Its scent helps deter some cabbage-family pests
❌ Keep away from
Strawberry
🛡️ Pest & disease prevention
Proactive ways to stop trouble before it starts. Tap a name with an arrow for its full guide
Pit young leaves; use floating row cover on seedlings
Cluster in growing tips; rinse off and conserve ladybugs
Green caterpillars chew leaves; handpick and use Bt or row cover
Small caterpillars riddle leaves; use row cover and rotate brassicas
🌾 Harvest & storage
Harvest choy sum when the first yellow flower buds appear but before they open, cutting the whole tender stem with its leaves and buds about 4 to 6 in above the ground. Cutting above a lower leaf often prompts side shoots for a second, smaller harvest. The entire stalk, leaves, stems, and buds, is eaten, and is at its sweetest young.
🥗 Nutrition & benefits
Choy sum is low in calories and rich in folate, vitamin C, vitamin A, and carotenoids. The whole stalk is stir-fried, steamed, or added to soups.
For educational and informational purposes only. HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.