Growing Hydroponic Ice Lettuce: Crystalline Ice Plant Leaves in Rafts

Hydroponic ice lettuce is the common iceplant, Mesembryanthemum crystallinum, grown for its thick leaves in water instead of soil. The USDA PLANTS Database lists it as an annual or perennial forb that was introduced to the lower 48 states. Indoors it fits the same raft or bucket you use for lettuce.

The short answer

Start seed in plugs, move rooted seedlings into net pots on a floating raft and run an aerated nutrient solution. Check pH and EC two to three times a week, give the plants about 14 hours of light and pick young leaves often while they are tender.

What is ice lettuce?

USDA PLANTS describes it as a forb, which means a soft stemmed plant rather than a woody one, and lists it as introduced in the lower 48. It is not a true lettuce, but it is harvested like other leafy greens.

How do you grow ice plant on a raft?

Virginia Cooperative Extension says deep water culture is also called a floating or raft system. Seedlings sit in rafts floating on the nutrient solution. Commercial rafts are made of polystyrene and are often 2 feet by 4 feet, though a home raft can be cut to fit any tub. Virginia Extension suggests checking EC and pH two to three times a week. It gives a pH of 5.5 to 6.2 for most crops and an EC of 1.2 to 2.0 mS/cm for many leafy greens.

The University of Minnesota Extension describes a smaller version for home growers. Net pots sit in a foam lid on a bucket or bin and should be only partly submerged. You can rely on the Kratky method, where the water level drops and leaves air for the roots, or add an air pump and airstone. Minnesota advises running lights about 14 hours a day with the grow area above 65°F. See caring for your hydroponic system for routine checks.

When do you pick the leaves?

Pick young leaves and shoot tips once the plant has several sets of leaves, and let the center grow on. UF/IFAS notes that baby leaf crops of greens such as spinach can be ready three to four weeks after planting. Plan your first cuts in that window and watch the plants rather than the calendar. A steady sowing plan from growing schedule for your hydroponics gives you a new raft as the old one slows.

Ice lettuce growing basics

Sources: USDA PLANTS Database, Virginia Cooperative Extension, University of Minnesota Extension, UF/IFAS Extension.

How to: step by step

1. Sow iceplant seed in starter cubes or plugs and set them under lights.
2. Cut a foam raft or lid to fit your tub and make holes for net pots.
3. Mix a leafy green nutrient solution and bring pH to 5.5 to 6.2.
4. Move rooted seedlings into net pots so only the lower part sits in the solution.
5. Add an airstone or use the Kratky method and let the level drop as roots grow.
6. Check pH and EC two to three times a week and top up as needed.
7. Pick young leaves and tips once plants are established.

Troubleshooting

Roots look brown and slimy: the roots sit too deep in still water. Lower the level or add an airstone.

Plants stall: check pH and EC first, then room temperature.

Algae on the raft: light is reaching the solution. Fill gaps around the net pots.

Grow a raft of iceplant greens

Iceplant fits any small raft or bucket system that grows lettuce. Compare substrates in hydroponic in different mediums and set up the room with hydro setup environment for more greens from Kind Seed Co.

Sources

• Mesembryanthemum crystallinum L. (common iceplant) plant profile, USDA NRCS PLANTS Database
• Hydroponic production of edible crops: deep water culture (DWC) systems (SPES-464), Virginia Cooperative Extension
• Small-scale hydroponics, University of Minnesota Extension
• Leafy greens in hydroponics and protected culture for Florida (HS1279), UF/IFAS Extension