Sub-Irrigation Options: Capillary Mats or Flood Tables
Sub-irrigation with drip tape has become popular because it conserves water and delivers water where plants need it most. However, there are some other methods of sub-irrigation that don't use drip tape.
Capillary mats are a newer type of sub-irrigation system that eliminates water waste by providing moisture from the bottom of the soil. These mats use perforated drip tubing embedded in fabric to send water up to the roots of potted plants. Automated dosers for fertilizer can be attached to the mat for fertilizer delivery. Algicides must often be used to prevent algal formation between mats and pots.
Flood Tables and Floors
Trough systems are sloped troughs on benches with tubing that circulates nutrient solutions to the water in the trough. Potted plants are set in the trough and take up water from below. Ebb and flow benches are similar systems that fill and then rapidly drain water through channels in the bench. The movement of water inhibits algal growth. In both, the flooding and emptying of benches are able to be controlled as needed, and water and nutrient solutions can be recycled. Some very large greenhouses install flood flooring with drainage and water capture gutters to apply flood style sub-irrigation on a larger scale.