It is a beautiful cool morning. Now that the heat has stopped for a few days, it is time to deep water your natives and especially your trees, native or not. Because natives mostly don’t like hot wet feet, it is best to water now before the next heat wave arrives. This helps heat-proof them.
How to deep water natives? If you have irrigation, turn it on before 9 a.m. or after 6 p.m. – it’s the law. Watering between 5 a.m. to 9 a.m is the best time. I prefer morning watering as most plants take up water and transpire it during the day. Some desert plants such as Cactus, Sedums and Dudleyas transpire at night through the CAM mechanism, but most – 93% – use water during the day.
Water for at least 20 minutes, and then check the soil moisture.
I know some of you prefer to water at the end of the day after work, and this is ok for the quick watering that rinses dust of the leaves of natives, or to rescue a plant, but it isn’t best for deep watering. Note that some plants will wilt in the hot afternoon and bounce back. Do not water to “rescue” these plants as it can kill them with kindness.
Checking soil moisture: Use an old screwdriver to dig a small hole to a depth of 2”. You can also use a core tool or an inexpensive moisture meter. Check for moisture at the bottom of the hole. If no moisture has reached the bottom of the hole, keep watering. Make a new hole to recheck (I know you know this, but…).
If you don’t have irrigation, an overhead sprinkler that attaches to the hose is fine for natives. Soak everything for at least 20 minutes, then check. Add water if necessary as above. If you have newly planted natives with planting wells or bowls around each plant, fill each bowl at least three times with a hose, then check.
To deep water trees, put a hose closer to the drip line than to the trunk. The drip line is on the ground where the canopy of leaves ends. Set the hose to drip once every second or two. Leave the dripping hose for 1 to 3 hours, depending on the size of the tree. Again, check the moisture 2” down.
“But, but…we’re not supposed to water!” Many water agencies are now trying to get the word out to keep watering the trees, especially if the lawn is allowed to go dry.
I heard noted climate and weather expert Bill Patzert of JPL speak about the drought last year. He pointed out that the current drought is not 3 (now 4) years old, it is 13 (now 14) years old. Because of this, trees are running out of reserve water. This year I’ve gone to many sites where trees are stressed or dying that just need a drink of water. Time to give it to them!