Yesterday I went home for lunch at noon and found plants that I had watered 18 hours before limp in the face of a blast furnace wind. With their dramatic drooping and leaf curling, potato vines and water-loving plants like hydrangeas and Joe Pye weed provide the visual equivalent of a scream to let you know they're thirsty.
But the urban plants I really worry about in this weather are our strong silent types: trees. Unless they are newly planted, they usually don't show that they're dry. We're so accustomed to treating trees as urban background noise that we just don't think about giving them a drink.
Please, please do.
The trees that seem as so tough draw most of their moisture and nutrients from roots that are in the top few inches of soil. Even oaks have most of their roots in the top three feet of soil. Water these guys regularly, and mulch under the canopy to help retain moisture in the ground, making sure the mulch is pushed away from the trunk. With new trees, putting a hose near the roots and letting it trickle for a couple hours does the trick. For established trees, letting a gentle sprinkler run over the root zone works.
Here's some more information from the U of M:

www.sustland.umn.edu/maint/trees.html#4b

When summer slipped into drought last year, I walked repeatedly by a newly planted boulevard tree that the city of Minneapolis had equipped with a "gator bag" — a bag that encircles the trunk and can be filled with water that slowly soaks into the ground around the tree. As far as I could tell, no one ever filled that bag to help that little maple along.
Here's what the gator bag looks like (this is not the tree I just mentioned):

While newly planted trees like that maple sometimes show their distress with signs like scorched leaves, mature trees may not show drought damage for years. Then branches begin to die high in the canopy and trees are struck by disease. Trees that are stressed by drought or other factors are the first to be attacked by pests like emerald ash borer and the oak pest two-lined chestnut borers.
Here's a University of Massachusetts site on the long-term effects of drought on trees:

extension.umass.edu/landscape/fact-sheets/long-term-drought-effects-trees-and-shrubs


Trees absorb pollution, put oxygen in the air, give us shade and provide beauty in our landscape. Let's treat them like the friends they are.