That’s the message of an article, Rx for landscape woes: Water trees and shrubs, not lawn, I posted today on the Cornell Horticulture blog.
Almost goes without saying, but here in areas of the Northeast that are suffering through record heat and in some cases less than half of normal precipitation (and much of that in big storms that mostly runoff), you can let the lawn go dormant and it will usually bounce back.
But for trees and shrubs — especially those that are just getting established — this can be a life-threatening situation. Even if woody plants have shed their leaves, you can water them now and they may refoliate. After two weeks, they’ve made up for the extra effort of putting out another set of leaves and are storing up energy for winter or future growth.