How to Grow Choi Sums
On this page
Choi sum is grown mainly for its leafy flowering stems: harvest begins 30 to 50 days after sowing, when the flower buds are fully developed but not yet open. It is a cool-season crop, and 15 to 25°C (59 to 77°F) gives strong stalks. Sow the seed about 0.6 cm (¼ in) deep, with plants 20 to 30 cm (8 to 12 in) apart (UF/IFAS Extension).
The short answer
- Site
- soil pH 5.5–6.8
- Biggest risk
- Club root
Core growing advice on this page is checked against named horticultural sources — see References.
Choi Sum (Brassica rapa var. parachinensis)
3 sources cited · Verified
At a Glance
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 5.5 - 6.8 |
| Soil texture | sandy soils referenced for spacing; fertile, well-drained generally (UF IFAS) |
| Drainage | well-drained |
| Lifecycle | annual or biennial grown as an annual |
| Edible parts | flowering stems, leaves, flower buds |
Soil & Growing Conditions
Water: moderate drought tolerance but susceptible to waterlogging; irrigate 1-2x weekly (UF IFAS)
Soil pH range
Span reflects genuine variation between the cited authorities, not a single agreed figure.
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing | 0 | Sow 0.24in (0.6cm) deep; transplants suit larger varieties with a longer growth period (UF IFAS). |
| Establishment | 3 | Cool-season growth at 59-77°F (15-25°C); spaced 11in between rows, 8-12in between plants; fertile, well-drained soil at pH 6-7 (UF IFAS). |
| Flower stem development | 5 | Flowering stems, leaves and buds develop; only the purple cultivar tolerates frost (UF IFAS). |
| Harvest | 8 | Harvest 30-50 days after sowing once flower buds are fully developed but still unopened; two to three harvests per season (UF IFAS). |
Harvest & Storage
When to pick: Harvest begins 30-50 days after sowing, once flower buds are fully developed but still unopened. Expect two to three harvests per season, 9,800-16,000 lb/acre yield (UF IFAS).
Diseases
Pests
Choi Sum, Seedling to Flowering Stem
Plan your Choi Sums planting
Timing for Choi Sums follows soil temperature and frost, not the calendar date. The Global vegetable planting calendar explains the method. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.
Growing Choi Sum in another region
Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.
Sources
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Mirrors FAO Ecocrop. Fetched and parsed directly for the numeric soil pH range.
-
Sow 5mm-1cm deep in late winter with frost protection, or from four weeks before to eight weeks after the last frost, and again in late summer with protection as temperatures drop. Direct sow 3-4 seeds per station then thin to the strongest, leaving 15-20cm between plants in rows 30-45cm apart. Soil pH 6.0-6.8, a cup of complete organic fertiliser per 3m of row, kept well watered throughout. HARVEST just before it flowers: flower buds appear at the centre of each plant and a stem forms quickly, so harvest as soon as buds are visible, cutting the plant at ground level with a sharp knife. IT DOES NOT REGROW, so successional sowing is necessary. Protect from flea beetles and cabbage moths with lightweight row cover, and guard against slugs and woodlice by keeping the ground clear of debris.
These 2 sources are specific to this region. The full list of 3 sources behind this guide (University of Florida IFAS Extension, Useful Temperate Plants, West Coast Seeds) is in the references of our UK guide to choi sum; they describe the plant itself, which is the same wherever it grows.
Frequently Asked Questions
What soil pH does choi sum need?
A pH of about 5.5–6.8. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect choi sum?
Our data links 1 disease and 3 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.
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How this guide is put together
The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against international horticultural research and extension sources. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.
Last verified 2026-09-02
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