Plants aren’t really refreshed by squirting water on their leaves on a hot day…you’re better off putting that water on their roots, not their leaves. In fact, unless they are new seedlings with small roots, you’re better off not hand-watering those plants at all. You get bored long before the soil is deeply moistened, and usually hand watering ignores the dry ground just beyond the drip line, where the roots are. 

Sometimes people are told “never water from above…put the water on the ground with a drip system instead.” First of all, your drip system has to be more than a single ring around each shrub or tree. And secondly, let me remind you that nature waters from above all the time. For some gardens, a sprinkler is the best, most thorough, way to water. Try and water in the morning, and let it run for as long as it takes to soak the ground down at least 10″ That might be three or more hours, but it’s impossible to say how long you’ll need to run your system; every sprinkler and home water pressure are different. 

And of course, you have to abide by local watering rules and restrictions. 

When planting areas of your garden, group plants according to their watering needs. Place drought-tolerant varieties together, and those that need more regular watering in a different area. Use organic mulches to help hold water in the soil and remember that rocks as mulch make soil hotter.

Watering cans are great for containers and small seedlings, but trying to water large plants with them isn’t very efficient. These make better ornaments than watering tools.