Capillary Mats Labor-saving, Economical Alternative To Hand Watering

Made with absorbent fabric lined with polyethylene film on the bottom and covered on top with perforated polyethylene or similar material, the mats help minimize evaporation while allowing water to move from the bottom of the mat up into the containers on top.

One advantage of capillary mats is that plants of different size and water requirement can be placed on the same mat without under- or over- watering individual containers. Other reasons mats are preferred to overhead sprinklers are that mats leave less water on the floor of the retail area, and staff don't have to spend as much time watering plants. The downside: capillary mats can be an expensive system to set up and maintain.

In a study published in the American Society of Horticultural Science journal HortTechnology, a research team from the University of Arizona used capillary mats and overhead sprinkler irrigation in a simulated retail environment to maintain annual and perennial plants in containers for various time periods during both summer and winter.

The researchers combined the results from both seasons and concluded that four species with dense canopies had larger canopy sizes when maintained on the capillary mats. Three species requiring more drainage had larger canopies with overhead irrigation, and five species were unaffected by irrigation systems. Additionally, substrate electrical conductivity was higher for some species in winter for plants on capillary mats, thus conserving fertilizer compared with overhead irrigation. Plants maintained on capillary mats required 71% less water in summer and 62% less in winter compared to the plants watered using overhead irrigation systems.

The study also included an economic analysis component comparing the investment required for setup and maintenance of plants in a retail situation using hand-watering, overhead sprinkler, or capillary mat irrigation. "The economic analysis indicates that capillary mats are a labor-saving alternative to hand-watering in a retail nursery and will compensate for the higher initial investment within less than one year", noted lead author Ursula K. Schuch.

Summarizing the research results, Schuch found that "overhead sprinklers were the most cost-effective system of the three because of less costly initial set-up and maintenance than the capillary mats", but added that sprinklers are not a true alternative to hand-watering in a retail situation because they interfere with customer traffic and retail workers.