Growing Hydroponic Bok Choy: Baby and Full Size Heads in DWC or NFT

The short answer

Hydroponic bok choy grows quickly in deep water culture or NFT systems, and you can harvest it as baby greens or full heads. It grows strongest in mild weather and turns bitter or bolts in heat. Hold the solution cool, check pH and EC often, and pick at the leaf stage you want.

Bok choy is one of the easiest leafy crops for a home system. It roots fast, needs no support and fits small spaces.

Which hydroponic system suits bok choy?

Two systems suit this crop well. The first is deep water culture, often called DWC or raft culture. The second is the nutrient film technique, or NFT.

The Virginia Cooperative Extension guide to deep water culture explains how DWC works. Plants sit in net pots on a floating raft, and their roots hang in a deep tank of aerated nutrient solution. An air pump and air stones supply oxygen to the water.

DWC holds a large volume of water. That volume buffers swings in temperature and nutrients, and it suits beginners and growers who want full size heads.

The Virginia Cooperative Extension guide to NFT systems describes the other option. A thin film of solution flows down shallow channels. Roots sit in that film and take up water, nutrients and air together.

NFT uses less water than a raft tank, and it also fits well on a rack or along a wall. Baby bok choy does well in NFT because the plants stay small and the roots never crowd the channel.

Either system can sit indoors under lights or in a greenhouse. Our post on creating the right environment for your hydro setup covers room conditions that apply to any leafy crop.

Sources: UF/IFAS Extension, Virginia Cooperative Extension.

How do baby and full size bok choy differ?

Baby and full size bok choy come from the same species. The difference is mostly variety and harvest timing.

The UF/IFAS Extension publication on bok choy describes the crop as a fast growing Asian leafy green. It notes that types vary in size, stem color and leaf shape. Some form short, compact heads. Others grow tall with thick white stalks.

Baby types are bred to stay small. You can harvest them as whole heads when they’re only a few inches tall. They fit dense spacing and quick cycles.

Full size types need more room and more time. Their stems grow thick and crunchy. They suit raft systems where each plant has its own wide hole.

Some growers pick standard varieties young and call them baby bok choy. That works too. The leaves are tender, though the heads may look looser than a true baby type.

How do you manage the solution for bok choy?

Bok choy is a cool season crop. It does well when the room and the water stay mild. Heat pushes it to flower early.

Warm water also holds less oxygen. Roots in warm water turn brown and slimy. Place the reservoir out of direct sun and away from heaters. In summer, a cooler room or a water chiller helps.

Read pH and EC two or three times a week. A pH meter and an EC meter are the two key tools. Leafy greens use nutrients steadily, so readings drift over time.

Top off the tank with plain water as plants drink. Replace the full solution on a regular schedule so salts don’t build up. Our post on caring for your hydroponic system explains cleaning and water changes.

When should you harvest hydroponic bok choy?

Harvest timing shapes flavor. Bok choy left too long in warm conditions can turn bitter and start to bolt.

For baby heads, cut the whole plant at the base once it reaches a usable size. For full heads, wait until the stems are thick and the head feels firm.

You can pick outer leaves and let the center continue growing. This stretches the harvest from each plant. Stop once you see a flower stalk rising from the center.

Harvest in the cool part of the day if your grow room warms up. Rinse leaves in cold water and chill them soon after cutting.

How to: step by step

1. Choose a baby or full size bok choy variety.
2. Start seeds in plugs and water them so they stay evenly moist.
3. Move seedlings to a raft or NFT channel once true leaves form.
4. Cool the solution in warm weather.
5. Check pH and EC every few days.
6. Harvest whole heads or outer leaves at the leaf stage you want.

Rockwool cubes, peat plugs and foam starter plugs all work for seed starting. Our post on hydroponic in different mediums compares them.

Space plants based on size. Baby types can sit close together. Full size heads need room so leaves get light and air.

Give seedlings bright light from the start. Weak light makes long, floppy stems that never fill out.

Troubleshooting

Bitter leaves. This usually happens when plants are harvested too late. Pick heads at the right stage and avoid a hot room.

Plants bolt. Excess heat and long days trigger premature flowering. Cool the room and harvest sooner.

Slimy roots. Warm water lacks oxygen. Cool the reservoir and check the air pump.

Yellow lower leaves. Nutrients may be low. Check EC and refresh the solution.

Tip burn on young leaves. Fast growth can outpace calcium movement. Improve airflow over the plants.

Bok choy offers a quick way to practice managing a hydroponic system. Kind Seed Co shares more garden ideas in outdoor growing.

Sources

• Bok choy, an Asian leafy green vegetable emerging in Florida (HS1337), UF/IFAS Extension, Bok choy
• Hydroponic production of edible crops: deep water culture (DWC) systems (SPES-464), Virginia Cooperative Extension, Hydroponic production of edible crops
• Hydroponic production of edible crops: nutrient film technique (NFT) systems (SPES-463), Virginia Cooperative Extension, Hydroponic production of edible crops