We take our campus trees seriously. They are valuable both environmentally and aesthetically, but they’re at risk because we’re dialing down the irrigation on the lawn around them. To avoid this conundrum teams from the UC Davis Arboretum and Public Garden’s grounds and landscape services team have started irrigating our younger trees with slow-release watering bags — a fancy description for those big green zippered sacks starting to appear at the base of young trees throughout campus.

Cary Avery, associate director of UC Davis grounds and landscape services, ordered about 240 of these bags and plans to reuse and rotate them throughout campus in an effort to get our trees through the summer while trying to save more water.

“We can’t rely on our sprinkler systems anymore to water our trees, especially since we’re cutting back watering our lawns even more dramatically than last year,” says Avery. “Instead, on young trees — those with trunks about 5 inches or less in diameter — we’re using SaplingSoakers and filling them up manually using our water truck.

Holes in the bottom of the bag allow the water to release slowly, giving the soil around the tree a chance to receive a deep water saturation with every irrigation, explains Avery. That’s what trees need plus, with this method, we see little if any run-off, and don’t lose water due to evaporation.”

Matt Forrest, irrigation supervisor for UC Davis grounds and landscape services estimates that these bags will save an average of at least 1000 gallons of water a year per tree.

“The water savings comes from the fact that we don’t have to water the lawn just to get young trees established,” explains Forrest.

Avery and Forrest know a thing or two about saving water in landscapes. Their teams have already cut back the campus’s utility (landscape) water use by over 30% — well ahead of Governor Brown’s 25% reduction mandate.

Have an older tree? TRIC it out using the Tree Ring Irrigation Contraption.