Normally needing little if any irrigation, trees are easy to overlook as gardeners adapt to lack of water. Yet trees are inarguably gardens’ most important living elements, and a drought imperils their very existence. Job #1 should be to save trees, not water.
Consider trees’ riches. Beyond their natural beauty, they reduce energy use by 10-35%, increase property values by 10-20%, improve ecosystems, and enhance quality of life. USDA Forest Service’s cutting-edge I-Tree Design assesses current and future value of specific trees at specific Google Maps locations. All these unsurpassed benefits, the decades it takes to recoup compared to other losses, and high removal and replacement costs catapult trees to top priority.
A drought stealthily and slowly wreaks havoc on these stalwart soldiers. Already stressed from little rain and high heat, conservation improvements such as lawn removal and less irrigation cut their water sources further. They suffer quietly, health declines, insects invade, and damage is often irreversible as they become both an eyesore and fire hazard.
Four years into the current drought, Governor Brown declared a state of emergency for California’s dead and dying trees. Estimates reveal the devastation: 22 million killed (USDA Forest Services, Oct. 2015) and 58 million suffering severe water loss (Carnegie Institute for Science study, Dec. 2015), with X-ray technology suggesting the toll will double to 20% of all trees. Three have succumbed on our 1.7 acres, and skeletons of dozens more dot nature trails that border our property.
Gardeners can protect their trees by first recognizing the need to do so, and then:
- Deep water mature ones monthly or so, and young ones weekly, according to species, size, and season. Use a soil probe to check moisture first, and water at the drip line, not at the trunk.
- Mulch with bark mulch or evergreen needles to maintain moisture and decrease temperature. Keep mulch a few inches from the trunk to prevent rot.
- Forgo fertilizer to avoid hurting roots with nitrogen salts or activating growth in parched conditions.
- Prune only dead or diseased branches. Avoid over-pruning that can shock and stimulate water needs.
Although residential sustainable gardening guides inexplicably ignore trees, a few lifestyle resources such as Sunset and Save Our Water and urban forest non-profits like California ReLeaf, Sacramento Tree Foundation, and California Urban Forest Council are on the case. A few public land government agencies are too, an example being Santa Monica Public Works’ guidelines for tree watering in a drought.