Leafy Greens for Hydroponics: Rafts Plus Towers
The right leafy greens for hydroponics are butterhead plus leaf lettuce, chard, kale plus Asian greens. University of Tennessee Extension notes that butterhead lettuce is the most common leafy crop in soilless systems. Spinach can work too, but it needs cool water and suits media based towers more than rafts.
The short answer
Start with butterhead or loose leaf lettuce in a raft or tower, then add chard, kale or Asian greens. UF/IFAS notes that chard adapts to many hydroponic systems plus resists Pythium better than spinach. Most leafy crops reach harvest about 6 to 8 weeks from seeding, according to University of Tennessee Extension.
Which leafy greens grow well in rafts and towers?
University of Tennessee Extension notes that kale, mustard, pak choy plus mizuna all grow well in small soilless systems. Those systems span rafts, channels plus towers. UF/IFAS notes that spinach in deep water or raft culture has been more of a problem than spinach in media based vertical systems.
| Green | System fit | Notes |
|---|---|---|
| Butterhead lettuce | Rafts, channels plus towers | Most common leafy crop in soilless systems |
| Loose leaf lettuce | Rafts plus channels | Can be cut young as baby leaf |
| Chard | Many system types | Less prone to Pythium than spinach |
| Kale | Rafts plus towers | Very hardy, harvest leaves several times |
| Asian greens | Rafts plus towers | Prefer cool temperatures, bolt in summer |
| Spinach | Media based towers | Prefers cool weather, bolts in heat |
Source: University of Tennessee Extension plus UF/IFAS Extension.
How do lettuce types differ in hydroponics?
University of Kentucky notes that butterhead, romaine plus leaf types are all common in hydroponics. It finds romaine harder to grow than leaf or butterhead types. University of Tennessee Extension notes many romaine, leaf plus oakleaf types can be cut young for baby leaf. University of Kentucky notes lettuce is harvested 21 to 35 days after transplant.
Which greens prefer cool water?
UF/IFAS notes spinach does well in cool weather (ideally 40 to 70 degrees F) but tends to bolt in heat. It notes Pythium can wipe out spinach when solution temperatures run high. Asian greens also prefer cool temperatures and bolt in summer. Chard lacks that cold preference, so it suits warmer rooms.
How to: step by step
- Note the greens your household eats most.
- Pick butterhead or loose leaf lettuce for a first crop.
- Add chard, kale or Asian greens for variety.
- Grow spinach only where the water stays cool.
- Transplant seedlings at 3 to 4 true leaves.
- Harvest outer leaves or whole heads on a schedule.
Troubleshooting
Greens bolt early: heat. Relocate cool season greens to a cooler spot or switch to chard.
Bitter leaves: prolonged heat brought on bolting. Harvest sooner plus cool the room.
Slow growth or poor color: low light. Raise light levels without placing lamps so close that leaves burn.
For related reading see caring for your hydroponic system, hydroponic in different mediums plus growing schedule for your hydroponics. Kind Seed Co also stocks cannabis seeds.
Sources
- Leafy crop production in small scale soilless and hydroponic systems (W 844 B), University of Tennessee Extension
- Hydroponic production of leafy greens other than lettuce (HS1279), UF/IFAS Extension
- Hydroponic lettuce production in controlled environments, University of Kentucky Center for Crop Diversification
- Growing lettuce in small hydroponic systems (HS1422), UF/IFAS Extension
FAQ
What is the easiest green to grow hydroponically?
Butterhead or loose leaf lettuce is the easiest place to start. University of Tennessee Extension notes butterhead is the most common leafy crop in soilless systems. University of Kentucky notes romaine is harder to grow than leaf or butterhead types, so save it for a second crop once you know your system.
Can spinach grow in hydroponics?
Yes, but it is fussier than lettuce. UF/IFAS notes spinach prefers cool weather (ideally 40 to 70 degrees F) but bolts in heat. Pythium can wipe it out when solution temperatures run high. It has done better in media based vertical systems than in deep water or rafts.
How long do hydroponic greens take?
University of Tennessee Extension notes leaf crops take about 6 to 8 weeks from seeding. That breaks down to 2 to 3 weeks as transplants, then 4 to 6 weeks in the system. University of Kentucky notes lettuce is harvested 21 to 35 days after transplant, and baby leaf can come sooner.
Do towers and rafts suit the same greens?
Mostly yes. University of Tennessee Extension notes lettuce, kale, mustard, pak choy plus mizuna grow well in small soilless systems including towers. Spinach is the main exception, since UF/IFAS notes it has been more of a problem in rafts or deep water than in media based vertical systems.
Which greens can be harvested more than once?
University of Tennessee Extension notes that kale, basil plus chard can be harvested several times by taking leaves instead of the whole plant. Many leaf lettuce types can also be cut young as baby leaf. Taking outer leaves lets the center grow on so one planting gives several harvests.
