UF-Designed Plant container Slashes Water Consumption

October 23, 1998

GAINESVILLE — A University of Florida-designed plant container that traps and recycles water could help commercial nurseries solve a vexing problem: how to give plants enough water without exceeding limits on water consumption.

The “multiple pot box” not only greatly reduces water use, it also spurs faster plant growth than possible with traditional containers, said Dorota Haman, a professor of agricultural and biological engineering and the designer of the container.

“The plants grow much faster because they are never water-stressed,” Haman said.

Nurseries typically use two methods to water plants: micro-irrigation and overhead sprinklers. Micro-irrigation, or delivery of water in small pipes to individual plants, is efficient for large plants and trees, but systems are too elaborate and expensive to use for smaller plants. As a result, nurseries typically use sprinklers for plants in 1- to 5-gallon sized pots, usually containing landscape ornamentals that are some of nurseries’ biggest sellers.

The problem with the sprinklers is, much of the water falls in gaps between the pots, intentionally kept separated to encourage foliage growth, Haman said. In Florida, water management districts require nurseries to obtain permits to use a limited amount of water, forcing them to struggle to balance the amount of water they consume with sufficient plant growth. Many other states also regulate nurseries’ water consumption.

In Florida, “at the current levels of efficiency of overhead irrigation, the amount permitted is at or just below that sufficient to grow many of the most popular species in containers with normal rainfall patterns,” said R.C. Beeson Jr., an associate professor in UF’s Central Florida Research and Education Center in Sanford and a co-developer of the container.

Before water management districts began regulating nurseries’ water consumption in the 1990s, it was estimated the average nursery used from 3.26 million to a little over 4 million gallons each year, making nurseries a high water user in the state, Beeson said.

To attack the problem, Haman designed a water-trapping container that holds nine 1-gallon pots. Water that misses the pots hits the surface of the container, then flows into a chamber beneath the pots. There, an absorbent polyester material allows the plants to soak up the water as they need it. In the event of heavy rainfall, a hole permits excess water to escape. The container also is designed so forklifts can easily move it around.

Experiments with sweet viburnum, a common ornamental shrub, revealed the plants required 84 percent less irrigation than the industry standard with a traditional system, Haman said. Not only that, the plants grew to marketable size in three months, half the time required for traditional systems, according to a paper the researchers published on their research in the March issue of the Journal of Environmental Horticulture.

“The experiment was conducted during months of relatively low rainfall in North Florida,” the paper notes. ” … It is likely that during the rainy season, only the first irrigation may be necessary and the rest of needed water can be provided by the rain.”

Tom Yeager, a professor in UF’s department of environmental horticulture, G.W. Knox, an associate professor in UF’s North Florida Research and Education Center, and Alan Smajstrla, a professor in the agricultural and biological engineering department, also were involved in the container’s development and related research. The research was funded by the Southwest Florida Water Management District, several nursery groups and with grants totaling $35,000 from the Horticultural Research Institute, the research division of the American Nursery & Landscape Association, a national trade association for the nursery industry.