Think about how often it rains in the summer in California and
where. The only areas that regularly receive significant
precipitation in the summer are the edges of California. So apply this
your plants. Desert species like a little water in the summer.
Most other plants are shutting down during this time. Winter and
spring water is far better for the health of the plant than summer
water. It is usually ok to water the
first summer or two.
to water (other than
washing dust off the foliage) beyond
the third summer unless you're willing to lose plants. Gophers,
squirrels, chipmunks, deer
and rabbits will
sometimes eat plants watered with drip
irrigation or watered in summer, while leaving the unwatered ones
alone. If the year is dry, water in March, April and May to make
up the difference. As soon as the soil becomes warm, turn the
water off; as soon as the soil cools, (except in really cold
locations) it's ok to water again.
During extreme years like 2013 it's difficult to find the balance. You'll need to water your older native plantings. The trick is to not kill the older plantings while keeping them alive. You can water indirectly, either adding extra water once a week between plants or a overhead sprinkler like a summer shower. A great time to add a few extra plants to the planting as you'll probably need to water anyway.