Kiddie Pool Hydroponics: A Cheap Shallow Raft Bed Outdoors
Kiddie pool hydroponics uses a plastic wading pool as the pond in a deep water culture raft bed. Foam rafts float on the solution while plant roots hang in it. No source here names kiddie pools, so the figures come from Extension pages on DWC ponds.
The short answer
Virginia Cooperative Extension notes DWC ponds run 4 to 12 inches deep. A wading pool fits that range. Float polystyrene rafts with lettuce spaced about 8 inches apart. Run air stones fully under the solution. University of Kentucky advises pH 5.5 to 6.5 plus covering open holes against algae.
What is a raft bed?
Virginia Cooperative Extension describes DWC as plants held in rafts that float on a pond of nutrient solution. Rafts are often polystyrene, about two feet by four feet. Some growers cut rafts from insulation board, though cut edges can shed flakes into the water. Rafts can move from the planting end to the harvest end.
How deep should the solution be?
Virginia Cooperative Extension gives pond depths of 4 to 12 inches. University of Kentucky float beds hold about 30 cm of solution. Oregon State University Extension notes a large volume of water buffers temperature swings. It advises a reservoir level within one inch end to end.
| Item | Figure | Source |
|---|---|---|
| Depth | 4 to 12 inches | Virginia |
| Lettuce spacing | About 8 inches | Virginia |
| pH | 5.5 to 6.5 | Kentucky |
| EC | 1.0 to 1.5 | Kentucky |
| Harvest | 30 to 60 days after transplant | Kentucky |
Source: Virginia Cooperative Extension plus University of Kentucky.
Which crops suit a kiddie pool system?
Oregon State University Extension lists lettuce, spinach, kale plus herbs for DWC. University of Kentucky transplants lettuce seedlings at 10 to 15 days plus harvests 30 to 60 days later. It cites air at 65 to 80 degrees F with humidity under 70 percent.
How to: step by step
- Set the pool on level ground.
- Fill to 4 to 12 inches deep.
- Sink air stones fully under the solution.
- Cut rafts to cover the whole surface.
- Set seedlings about 8 inches apart.
- Cover empty holes with black plastic.
Troubleshooting
Green water: light on the solution. Kentucky advises covering open holes with black plastic.
Uneven roots: sloped pool. Oregon State advises a level within one inch.
Foam flakes: cut board edges. Virginia notes cut insulation board can shed flakes.
For more on root media see hydroponic in different mediums plus caring for your hydroponic system. Read aquarium water for cannabis. Kind Seed Co also stocks cannabis seeds.
Sources
- Hydroponic production of edible crops: deep water culture (DWC) systems (SPES-464), Virginia Cooperative Extension
- 5 steps to successful float bed lettuce production (CCD-FS-36), University of Kentucky Center for Crop Diversification
- Hydro hints: deep water culture (EM 9455), Oregon State University Extension
- Hydroponics for the home gardener, UC Master Gardeners of Orange County
FAQ
How many lettuce plants fit in a kiddie pool?
Virginia Cooperative Extension spaces lettuce about 8 inches apart on DWC rafts. A raft about two feet by four feet holds roughly 18 heads at that spacing. Count how many rafts fit the pool surface, then multiply by the plants each raft holds.
Do you need an air pump?
University of Kentucky float beds use air stones fully under the solution to supply oxygen to roots. UC Master Gardeners note DWC uses an air pump with stones, while the passive Kratky method relies on an air gap instead of a pump.
What pH suits a kiddie pool system?
University of Kentucky advises a float bed solution pH of 5.5 to 6.5 with an EC of 1.0 to 1.5 for lettuce. Check both figures often, since evaporation plus plant uptake change the solution over the weeks before harvest.
Can a kiddie pool system run in summer heat?
University of Kentucky notes lettuce in float beds does well with air at 65 to 80 degrees F plus humidity under 70 percent. Oregon State University Extension notes a large water volume buffers temperature swings, which helps a wide pool.
How do you stop algae in the pool?
University of Kentucky advises rafts that cover the whole surface plus black plastic over open holes so light cannot reach the solution. Oregon State University Extension notes covering the water also cuts evaporation from the reservoir.
