How to Grow Bok Choy Hydroponically

Quick answer

Hydroponic bok choy reaches full harvest in 35–45 days at pH 6.5, EC 1.8, DLI 14 mol/m²/day. NFT, raft, and DWC all work; bok choy is the fastest fully-headed crop in commercial hydroponics after baby leaf [UCD-LET-01].

Conditions

Best system

NFT and raft are commercial standards. DWC for hobby. Bok choy's compact rosette and shallow root system make it ideal for high-density NFT channels — 15 cm in-channel spacing for baby, 25 cm for full-size [CORN-CEA-01].

Kratky works for a single cut of baby bok choy at day 25, but the static reservoir warms under lights and the plant bolts before reaching full size [KRATKY-ORIG].

Varieties

• Joi Choi. Full-size, white-stem, slow to bolt. Commercial standard.
• Mei Qing Choi. Green-stem, baby type, fastest.
• Shanghai Green. Light green stems, tender, restaurant favorite.
• Black Summer. Heat-tolerant; useful in summer rooms.

All standard cultivars run on identical hydroponic parameters [USDA-NUT-01].

How it works

Bok choy (Brassica rapa subsp. chinensis) is a non-heading Chinese cabbage. The plant forms a tight rosette of glossy leaves around a thick white or green petiole base. Unlike heading cabbage, bok choy doesn't need extended growth time to form a head — it reaches harvest size in roughly half the time of cabbage [UCD-LET-01].

The bolt trigger is the same as most brassicas: sustained heat above 24 °C and photoperiods over 14 hours.

Failure modes

• Bolting. The dominant failure. Cool the room and shorten photoperiod.
• Slugs and snails in mixed setups. Bok choy is a magnet. Indoor closed systems rarely see this.
• Tip burn on inner leaves. Calcium transport failure. RH too high or VPD too low for transpiration. Increase airflow.
• Aphids. Brassica-typical. Inspect weekly [GROWER-LOGS].

Baby vs full-size programs

Two distinct production models:

• Baby bok choy. Direct seed at 10 cm spacing, harvest whole plant at day 25 when 12–15 cm tall. Highest plants per square meter.
• Full-size. Transplant at day 12, harvest at day 40 when 25–30 cm tall. Larger per-plant yield, fewer rotations.

Restaurants typically prefer baby; retail prefers full-size [GROWER-LOGS].

Nutrient considerations

Bok choy tolerates a wide EC window — anywhere from 1.5 to 2.5 produces good results. Push toward EC 2.0 for full-size to support thicker petioles. Calcium and boron are the two nutrients to watch in brassicas; deficiencies show as deformed inner leaves and hollow stem [OSU-NUT-01].

Light and DLI

Bok choy reaches harvest size at DLI 12–14. Higher DLI doesn't help — the bolt risk rises with both light and heat [PPF-DLI-01]. Photoperiod 12 hours indoors is conservative and reliable; 14 hours speeds the cycle but pushes the bolt trigger closer.

Post-harvest

Bok choy holds 7–10 days refrigerated at 2 °C in sealed bags. Wilted plants recover briefly with a cold-water bath but lose quality fast after that. The thick white petiole base bruises easily — handle gently from cut to pack [USDA-NUT-01].

What we recommend

Run bok choy in NFT at 20 cm spacing, EC 1.8, pH 6.3, water 18 °C, photoperiod 12 hours, with harvest at day 40. Rotate plantings every 7 days for a continuous line. Skip baby bok choy if you can't keep RH under 70% — the dense rosette traps moisture and invites soft rot [UCD-LET-01].