Deep water culture (DWC) is our primary hydroponics method for lettuce. We operate multiple DWC beds across all three greenhouses, totaling nearly 1,500 square feet of growing area. We have more than 5,000 plants growing in these beds at any given time.

How Does DWC Work?

In a DWC system, plants are suspended above a nutrient rich solution. Most other hydroponic systems alternate between exposing roots to air and drenching them in water. However, in DWC systems, the roots are continuously submerged in the nutrient-rich water. In our systems, we use foam rafts to float the lettuce on top of nutrient ponds.

Because the roots are constantly submerged in water, a key piece of DWC operations is to ensure the water stays well oxygenated. This is typically accomplished with air pumps (similar to oxygenating a fish tank) or venturi attachments on circulation pumps – which draw air directly into the water flow.

Maximizing Space Efficiency

In our greenhouses, we use an approach to maximize the use of our available growing spaces. We start our plants in grow trays, allowing them to grow 10-14 days until they are ready for the hydroponics. When ready, we place them into 2′ x 4′ rafts that holds 72 plants. The plants will typically spend 2-3 weeks (depending on the time of year) in these 72-count rafts while they grow. Once they become too big for this spacing, we transplant them into other rafts that hold either 36 or 18 plants per raft. Although this involves extra labor, we are able to maximize efficiency of space by packing plants in according to how big they are.