Denver’s first day of summer will arrive Saturday, June 20, at precisely 3:23 p.m.

Of course, summertime weather doesn’t appear with the flick of a switch. We’ve already experienced some hot, dry spells in May and so far in June, which is why Denver Water’s annual summer watering rules go into effect May 1.

But these are just dates, not predictors of the bipolar Colorado climate. Weather patterns are the true indicators for proper watering habits.

When it comes to knowing when and where to water, follow these rules of (green) thumb:

Trees and shrubs: During prolonged dry periods, water once or twice a month, using 10 gallons of water for each inch of the tree’s diameter.

Vegetable and flower gardens: No matter what time of year it is, Denver Water suggests always watering your garden by hand to ensure water goes only into the soil where the plant roots can use it. It’s also a good idea to check your soil moisture by using a small trowel prior to watering.

Lawn: Create your own watering guide for the summer that's specific to your lawn using the scheduler here. Adjust your watering times based on rainfall, type of grass or plants, sunny or shady locations and other characteristics.

Watering is not an exact science. Every yard is different, so there’s no one-size-fits-all guide to landscape care.

But as the days grow warmer, start the watering season off right by working with Mother Nature, no matter what she has in store.