The ebb-and-flow system is very common and is quite familiar to most growers. The system consists of a shallow, molded plastic bench top which is flooded to water and fertilize the plants. When irrigation is complete the remaining solution drains from the bench and is pumped back to a storage tank.
Ebb-and-flow is very versatile because the bench tops can accommodate all sizes of pots and bedding plant flats (although not on the same bench or irrigation zone at the same time because of the differences in water absorption rates between container sizes). The bench tops can be installed on existing frames and, with the rolling feature, ebb-and-flow benching can be 80-90% space efficient.
Ebb-and-flow benches are easy to retrofit in clear span greenhouses.
Flooded floor systems
In this system the entire floor of the greenhouse is covered with a concrete carefully designed and installed to pitch toward openings in the floor. Through these openings the irrigation solution enters to flood the floor and, following flooding, the excess drains back to the storage tank.
The floors can be installed with bottom heating and divided into zones for separate flooding and bottom heating. Flooded floors can be used to grow plants in all container types and sizes as long as separate irrigation zones are provided for each type. Space efficiency is about 85-95%.
Most greenhouses with flooded floors were built with them. The bottom heating option an efficient way of providing the proper growing temperature for the plants because the air close to the plants is heated and the larger volume of the greenhouse does not have to be heated so much.