I planted 12 bok choy seedlings on the same morning and split them across three hydroponic systems. Fifty-one days later I weighed every head. The spread between the best and worst was bigger than I expected, and it changed which system I will bother with next time.

A note before the numbers: this was one run in one spare room, not a lab study. Your temperatures and light will shift the results. But the gaps were wide enough that the pattern is worth sharing.

The setup: same seed, same room, three systems

All 12 plants were Brassica rapa subsp. chinensis (the white-stem bok choy, not the soup spoon type), started from the same seed packet and moved to the systems at the same two-leaf stage. The room sat at 19 to 23°C. I ran a single T5 LED bar over each, about 14 hours a day, since the room has no window worth mentioning.

The three systems: - Kratky: three plants in a 10-liter black tub, net pots, no pump, water topped up by hand. - Deep water culture (DWC): three plants in a 12-liter reservoir with an air stone running 24/7. - Nutrient film technique (NFT): six plants on a 1.5-meter channel with a small recirculating pump.

All used the same base nutrient at 1.2 to 1.6 mS/cm EC and pH held between 5.8 and 6.2. See the hydroponic nutrients guide for how I mix and check that.

What I measured, and how

At day 51 I cut each head at the base, shook off water, and weighed it on a kitchen scale. I also logged the day each plant reached a usable "baby bok" size (about 12 cm tall) and how much time I spent on maintenance.

Kratky: the lazy winner

The Kratky tub needed almost nothing from me after the first fill. By day 30 the three plants were a solid 12 to 14 cm and crisp. Final weights averaged 180 g per head. The leaves were a touch lighter green than the DWC plants, which tells me nutrient strength could have gone up a notch, but nothing looked deficient.

For a beginner this is the system I point people to first. No pump to fail, no electricity bill, and the Kratky method guide gets you started in an afternoon.

Deep water culture: biggest but neediest

DWC produced the heaviest heads by a clear margin, averaging 240 g, with the widest stems. The catch was attention. The air stone ran constantly, the reservoir warmed up near the heater one week and I had to swap in a frozen bottle to keep it under 24°C, and the water level needed checking every few days.

If you want max yield and do not mind a daily glance, DWC wins. The deep water culture walkthrough covers the air-stone detail that keeps roots from drowning.

NFT: fastest start, then it stalled

NFT sprinted out of the gate. Those six plants hit baby size by day 24, a week ahead of the others, because the roots met nutrient immediately. Then it flattened. By day 51 the average weight was 165 g, the lowest of the three, and two channel plants bolted (went to flower) when the pump hiccuped for a day during a power blip.

NFT is great for leafy greens you harvest young and often. For a one-and-done bok choy crop it was more fuss than the result deserved. Compare it with NFT explained before you commit.

The numbers side by side

  • Kratky: 180 g avg, baby size day 30, about 5 minutes total care.
  • DWC: 240 g avg, baby size day 28, about 15 minutes weekly.
  • NFT: 165 g avg, baby size day 24, about 10 minutes weekly plus the pump risk.

The DWC heads were about 33 percent heavier than Kratky and 45 percent heavier than NFT. The Kratky plants cost me the least time by a wide margin.

What I would do differently

Next run I will push Kratky nutrient to 1.8 mS/cm and see if the color deepens without tipping into tip burn. I will also run DWC but with the reservoir moved off the warm floor. NFT I would reserve for cut-and-come-again lettuce, not full bok choy heads, which is what indoor hydroponic lettuce is built for anyway.

If you want the whole starter kit in one box, a complete hydroponic kit gets the plumbing out of the way so you can focus on the growing.

The data surprised me because I expected the pumped systems to win outright, and instead the no-pump Kratky tub gave me 75 percent of the DWC yield for a fifth of the effort. If you are choosing where to start, the Kratky method guide is the one I would open first, then graduate to DWC once you trust your nutrient mixing.