After periodic deluges that leave the Midwest struggling to dry out, it may seem unnecessary to think about the importance of watering wisely and efficiently. But it's not unusual for one type of extreme weather to be followed by the opposite extreme, and an extended period of hot, dry July weather could affect home gardens at any time.
Remember the Golden Rule
Proper watering practices help to prevent drought-related stress,which can leave many plants vulnerable to disease and insect problems. Keeping an eye on a rain gauge in your own backyard “ecosystem” is an important step to keeping your carbon-absorbing, oxygen-producing plants both healthy and looking beautiful.
When natural rainfall is less than 1 inch a week, it's time to think about providing supplemental irrigation, especially for newly planted trees and shrubs, and other long-lived plants such as perennials. Even drought-tolerant plants need up to three years for their extensive root systems to become established. Investing time and resources on the needs of these plants now will provide future dividends on your landscape investments.
The golden rule for most plants is to water root zones deeply but infrequently. Too little water provided too often can result in shallow root systems that leave plants less able to tolerate drought. It can also cause excessive weed growth and the unwelcome appearance of fungal diseases. For a mature tree, the root zone can extend well beyond outside edge of the canopy known as the drip line.
Watering early in the morning provides more time for the sun to dry leaves of shorter plants, and reduces the amount of water lost to evaporation. Unless irrigation water comes from a water barrel, cistern, or well, it's too energy-expensive to waste. According to the EPA, letting a faucet run for just five minutes uses as much energy as a 60-watt light bulb left on for 14 hours. And since energy production generally results in carbon emissions, using water efficiently also helps to mitigate the leading cause of climate change.
Using drip irrigation instead of overhead sprinklers and weather-based systems are other ways to reduce evaporation. Existing systems can often be easily and inexpensively retrofitted with a device that monitors rainfall, ensuring plants are watered only when they need it.
No matter what kind of watering system you use, your important plants will benefit from a 2- to 3-inch layer of organic mulch.