Hydroponic Water Lily Tub: Growing Hardy Lilies in Half Barrels
A hydroponic water lily tub is a half barrel or large tub that holds a potted water lily under still water. The rhizome roots in heavy soil while the round pads plus flowers float at the surface.
The short answer
Plant a hardy water lily rhizome in a pot of silt loam or clay soil with fertilizer pellets plus a pea gravel cap. Colorado State University Extension suggests 8 to 12 inches of water above the crown. Give the tub full sun. NC State notes lilies prefer still or slow water.
Which water lilies suit a tub?
Utah State University Extension names two groups. Hardy water lilies survive winter in most Utah ponds. Tropical lilies grow as annuals or need shelter from cold. NC State Extension adds that tropical types come in day blooming plus night blooming forms.
NC State lists water lilies as hardy in USDA Zones 3a to 9b. Depending on size, they grow in water from 3 inches to 2 feet deep. University of Illinois Extension notes dwarf water lilies can even grow in table top bowls.
How deep should the lily pot sit?
Colorado State notes a pot 12 inches across and 10 inches deep suits most aquatic plants. It suggests 8 to 12 inches of water above the crown of a water lily. Utah State gives 18 to 24 inches below the surface for hardy lilies in a pond, so a half barrel sits at the shallow end.
Illinois Extension advises setting pots on bricks, stones or upturned pots to reach the right depth. Too deep a pot can drown a shallow water plant.
| Factor | Target | Source |
|---|---|---|
| Water over the crown | 8 to 12 inches | Colorado State |
| Pot size | 12 inches across, 10 inches deep | Colorado State |
| Soil | Silt loam or clay, not potting mix | Utah State |
| Fertilizer at planting | Two to four pellets | Utah State |
| Water flow | Still or slow moving | NC State |
Source: Colorado State University Extension, Utah State University Extension plus NC State Extension.
How do you plant a lily rhizome?
Utah State advises filling the pot with silt loam or clay soil and leaving 2 to 3 inches of space at the top. Skip potting mix or a light soil. Set the rhizome at a 45 degree angle on top of the soil without covering it. Add two to four fertilizer pellets at planting.
Cover the soil with pea gravel or a few large rocks to hold it in the pot. Colorado State advises potting hardy lilies from mid April through May. Tropical lilies go in from mid June once the water holds 68 degrees F or more.
How do tub lilies get through winter?
NC State notes hardy lilies go dormant in winter and survive if the rhizomes sit below the freeze line. Cool regions grow tropical lilies as annuals.
How to: step by step
- Fill a half barrel with clean water in full sun.
- Pot the rhizome in silt loam or clay soil.
- Set it at a 45 degree angle with the top uncovered.
- Add two to four fertilizer pellets.
- Cap the soil with pea gravel.
- Raise the pot on bricks to about 8 to 12 inches below the surface.
Troubleshooting
Slow to bloom: a pot set deep. Utah State notes deep hardy lilies take longer to reach the surface. Raise the pot.
Soil clouding the water: no gravel cap. Add pea gravel over the soil.
Few flowers: shade or low feeding. NC State notes lilies are heavy feeders.
For more on root media see hydroponic in different mediums. Read caring for your hydroponic system for system care. See pond water for cannabis plus aquarium water for cannabis for related water notes. Kind Seed Co also stocks cannabis seeds.
Sources
- Tips for growing water lilies, Utah State University Extension
- Nymphaea (water lily), NC State Extension Gardener Plant Toolbox
- Planting the water garden container, University of Illinois Extension
- Water gardens: planting aquatic plants (PlantTalk 1026), Colorado State University Extension
FAQ
Do water lilies need moving water?
No. NC State Extension notes water lilies prefer non moving or slow moving water. A still half barrel suits them.
What is the difference between hardy and tropical lilies?
Utah State University Extension notes hardy lilies over winter in most ponds while tropical lilies grow as annuals or need shelter from cold. Tropical types like warmer, shallow water of 6 to 10 inches.
Can tub lilies freeze in winter?
NC State notes hardy water lilies go dormant in winter and survive if the rhizomes sit below the freeze line. Tropical lilies are grown as annuals in temperate areas.
How often should water lilies be fed?
NC State notes water lilies are heavy feeders and advises a fertilizer made for water lilies used by the container directions. Utah State adds two to four pellets in the soil at planting.
Do water lilies need full sun?
Utah State notes hardy water lilies prefer a sunny spot. NC State notes most lilies prefer full sun, though some tolerate some shade.
