Quick growing conditions
Air: approximately 16–21°C; nutrient solution: around 15–22°C
Approximately 5.5–6.0
Around 1.5–2.5 mS/cm
12–14 hours daily; around 10–20 kilolux under white grow lights
Suitable systems
- NFT
- DWC
- Kratky
Substrates
- rockwool
- coco coir
How to Grow Pak Choi Hydroponically at Home
Pak choi, also called bok choy (Brassica rapa subsp. chinensis), is a fast-growing leafy vegetable with tender leaves and crisp, juicy stems.
Hydroponic pak choi suits small indoor systems. You can harvest individual leaves or grow compact whole rosettes for stir-fries and soups. Unlike heading cabbage, pak choi does not form a tightly enclosed head.
Choosing a Variety
Choose compact varieties for limited growing space and varieties with resistance to bolting, especially in a warm room.
‘Summer Breeze’ and ‘Glacier’ have good bolting resistance. ‘Choko F1’ produces mild leaves and crisp stems. Baby pak choi varieties are useful when you want smaller plants and earlier harvests.
Bolting resistance reduces the risk of premature flowering, but does not eliminate it.
Main Growing Conditions
These are practical starting guidelines. Growth depends on the variety, light intensity and conditions around the roots.
| Parameter | Guidance |
|---|---|
| Air temperature | Cool to mild conditions are preferable. Approximately 16–21°C favours crop quality; growth is possible outside this range |
| Nutrient solution temperature | Around 15–22°C is a practical starting range, not a compulsory limit. Avoid unnecessary heating in a cool room |
| Lighting | Start around 10–20 kilolux at leaf level under white grow lights |
| Light duration | Start with 12–14 hours daily and provide a regular dark period |
| pH | Approximately 5.5–6.0 |
| EC | Around 1.5–2.5 mS/cm has supported pak choi production in published NFT trials |
| Air movement | Gentle airflow between plants; avoid persistent condensation |
The lighting settings are approximate home-growing suggestions, not a reproduction of the nutrient-profile trial. Lux readings depend on the lamp spectrum.
Pak choi can grow in cooler conditions, although development slows. Prolonged cold exposure in young plants can encourage flowering when warmer conditions return. Heat, water stress and long days can also increase bolting risk.
Choose a suitable variety and maintain steady conditions rather than trying to hold one exact temperature.
Suitable Hydroponic Systems
Pak choi grows well in NFT and can also be grown in aerated DWC or a properly designed passive system.
In DWC, provide oxygen to the roots. In a passive Kratky system, preserve the air gap above the solution as the water level falls. Do not refill so high that established air roots become submerged.
Keep the crown above the nutrient solution and cover the reservoir to reduce algae growth.
Allow approximately 20–30 cm between plants intended for larger rosettes. Smaller crops can be grown closer together and harvested earlier.
Recommended Nutrient Profile
The following profile comes from “Leafy Asian Vegetables and Their Nutrition in Hydroponics” by Sophie Parks and Carly Murray, published by NSW Industry & Investment.
The guide reports successful NFT cultivation of pak choi using Huett’s lettuce formulation.
All concentrations below are mg of element per litre of working solution. N is total nitrogen; P and K are elemental concentrations, not P₂O₅ and K₂O.
| Element | mg/L |
|---|---|
| N | 116 |
| P | 22 |
| K | 201 |
| Ca | 70 |
| Mg | 20 |
| S | 26 |
| Fe | 2.50 |
| Mn | 0.22 |
| Zn | 0.15 |
| B | 0.21 |
| Cu | 0.03 |
| Mo | 0.01 |
Source: Table 1, printed page 9.
The guide associates this particular profile with an EC of approximately 1.6 mS/cm. Your measured EC will also depend on the source water.
Use this solution as a starting point and modify it according to growth and your system. Account for nutrients already present in the water before calculating fertilizer quantities.
Pak choi is harvested for vegetative growth, so a separate flowering or fruiting profile is unnecessary.
For calculating your nutrient solution, use the NPK Calculator.
Daily Care
Check the reservoir level, pH and EC regularly. Keep water and nutrients consistently available without allowing the roots to dry out.
Give leaves enough space for airflow. Remove damaged or decaying outer leaves, while preserving healthy foliage.
If young leaves develop scorched edges, check the complete nutrient mix, root health and growing conditions before adding more calcium.
If plants stretch and develop weak stems, review light intensity and spacing. If a flower stalk appears, harvest promptly while the leaves and stems are still tender.
Pollination is not needed when growing pak choi for leaves and stems.
Harvesting
Baby leaves can be ready approximately 30 days from sowing. Semi-mature and full-sized rosettes commonly take around 45–75 days.
These are general crop timings, not a guaranteed hydroponic schedule. Variety, temperature, lighting and the desired harvest size affect the result.
For repeated picking, remove a few large outer leaves and leave the centre intact. For a whole-plant harvest, cut through the base with a clean knife.
Harvest while the rosette is compact and the stems are tender. Use freshly harvested pak choi promptly, or refrigerate it.
Common Pests and Diseases
Hydroponics does not make pak choi immune to pests or infection.
- Flea beetles leave small holes in the foliage.
- Cabbage caterpillars chew larger holes and damage young leaves.
- Alternaria can cause leaf spots.
- Black rot can produce yellow, V-shaped areas along leaf edges.
For pesticide-free home growing, use clean equipment, inspect incoming plants and keep insects out with suitable mesh.
Remove caterpillars by hand, isolate affected plants and promptly discard badly diseased material. Keep leaves from remaining wet for long periods.
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Ranges depend on cultivar, stage, water, and environment.
Calculator overview →Sources
- NSW Industry & Investment: Leafy Asian Vegetables and Their Nutrition in Hydroponics
- Ding et al. (2018): Effects of nutrient-solution EC on hydroponic pak choi
- Royal Horticultural Society: How to grow pak choi
- Iowa State University: Bok choy cultivar trial for spring high tunnel production
- University of Minnesota Extension: Growing Chinese cabbage and bok choy