- Author: Michelle Davis
NOAA, the National Oceanic and Atmospheric Administration is predicting a 70% chance of a La Niña weather pattern for the upcoming 2021-2022 winter. Rain comes from clouds that form over warm ocean water, and La Niña will be blowing that warm water that we want to the Western Pacific. That means rain for destinations like Australia, but for us in the Eastern Pacific, cold ocean water means less rain. Get ready for the potential of another drought year. We have survived a lot of droughts, but the last one taught many home gardeners that trees suffer greatly and don't show it right away. Trees dwindle over years and finally die. Look at the devastating effects of past drought and now fire on California's forests.
How important are your home's trees to you? The trees in my front yard partially shade my house during the summer shading the front and helping me to save on my PG&E bill. Trees help to cut down on pollution. Their roots prevent erosion. And they are beautiful.
Here are some tree irrigation recommendations from the Sacramento Tree Foundation and Sacramento's Regional Water Authority.
Lawn irrigation is not usually enough to keep nearby trees alive and thriving. Trees younger than 5 years of age require a good amount of water to develop deep root systems. That water needs to be delivered slowly and deeply. Check the soil first with a moisture meter. If it is not moist to 8 inches deep, the most water-efficient delivery system is a 5-gallon bucket. Drill a 1/8” hole on the side of the bottom of the bucket about 1 inch from the bottom. Put a piece of duct tape over the hole and put the bucket close to the tree about 1 foot from the trunk. (Don't get the tree trunk wet.) Fill the bucket with water and take off the tape. Let the water gradually seep from the bucket. Repeat on the opposite side of the tree. As the tree matures, move the buckets to the edge of the tree's canopy, the drip line in other words. These younger (to age 5) trees will usually need 2-3 extra buckets per week equaling 10-15 gallons of water. A circle of mulch around the tree aids in retaining that moisture. Just make sure the mulch isn't touching the tree.
For more mature trees, try checking the moisture by shoving a screwdriver into the soil around the tree. If you can't push the screwdriver deeper than 3 inches into the ground, it's time to get busy. Older trees need deep thorough irrigation extending from the tree to just beyond the drip line. The recommendation is to use soaker tubing around the tree in concentric circles and run it at low pressure for one hour checking for runoff and keep repeating until the soil is moist 6 inches below the surface. Once this has been achieved, check again in 3-4 weeks to see if soaking needs to be repeated. Timing is important – soak early in the morning or soak in the evening for less evaporation. And mulch, mulch, mulch! The Sacramento recommends 6 inches of mulch, 6 inches from the tree trunk.
Keep in mind that any tree planted in or close to a “hell strip”, paved surface or building foundation will need more water. If planting a tree this fall, try to pick a drought-resistant or a native tree. They will still require the watering schedule as listed but just for the first couple of years.
If you are choosing between irrigating the lawn or a tree, pick the tree. The grass will come back, but the tree won't. A 1000 square foot lawn in the Sacramento Valley needs 25,000 gallons of water per year. How many of your trees could use that water?