How to Grow Choi Sums USA
On this page
Choi sum (Brassica rapa var. parachinensis) — annual or biennial grown as an annual.
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
When to sow and plant Choi Sums depends on your own frost dates. Check the USA vegetable planting calendar. 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
-
Cool-season crop thriving at 59-77°F (15-25°C). Only the purple cultivar tolerates frost; grow mid-to-late spring and early autumn in warm climates to avoid frost damage. Sow seeds 0.24in (0.6cm) deep; transplants suit larger varieties with extended growth periods. Spacing: 11in (28cm) between rows, 8-12in (20-30cm) between plants in sandy soils. Soil pH 6-7, fertile, well-drained; avoid waterlogging, use raised beds if necessary; tolerates moderate drought but susceptible to waterlogging. Fertilization follows cabbage recommendations (100-150 lb/acre nitrogen depending on phosphorus levels, matching potassium). Irrigate once or twice weekly based on evapotranspiration. Harvest begins 30-50 days after sowing, once flower buds are fully developed but still unopened; two to three harvests per season, 9,800-16,000 lb/acre yield. PESTS: beet armyworm, fall armyworm, aphids, diamondback moth, green looper caterpillar, white butterfly caterpillar. DISEASES: bacterial soft rot with excessive moisture (over 40% volumetric soil water or 300mm rainfall/month).
These source is 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
Almost everything on this page resolves to your own frost dates rather than the calendar — the last spring frost moves by roughly two months between zone 3 and zone 10. The USA Garden Planner works from your zone so the timing is already decided before the season starts.
Get the USA Garden Planner →Instant PDF download · Written for US growing conditions
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 USDA hardiness-zone and frost-date data, with Cooperative Extension sources cited directly where one exists for a crop. 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
Related guides
More from the same group (brassicas & mustards):
Growing advice for your part of the USA
Timing and conditions change a lot inside one country. These guides cover frost dates and growing seasons region by region.
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Keep going
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.