How to water your garden wisely in the summer heat

You've probably heard the expression, "Work smarter, not harder." The same idea can apply to watering your garden in the dead of summer - when standing in the blazing heat, hose in hand, or swatting away mosquitoes while positioning your sprinkler are about the last things you want to do.

Though watering obviously becomes more critical as temperatures rise, deploying the right tools and strategies can make your routine easier and less frequent. In fact, you may already be watering too often. "Intuitively, people think, 'Oh, it's hot so I'll water every day,'" says Cory Tanner, director of the horticulture program team at Clemson University. But just watering a little every day - rather than giving your garden a thorough, but less frequent soak - "actually encourages shallow rooting."

Herewith, advice from gardening experts to help you water more efficiently in the heat.

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Know your soil

Soil type plays a crucial role in the amount of water that can be absorbed and retained. "How much sand, silt and clay is in the soil informs all of our irrigation and nutrient management recommendations," says Melanie Stock, assistant professor and urban and small farms extension specialist at Utah State University.

Sandy soil, for example, does not hold water well. If yours is sandy, she recommends adding compost to increase its ability to absorb moisture so you won't have to water as frequently. She says loam or silt loam soil can retain one-and-a-half to two inches of water in the top foot of dirt, and clay soil holds up to two-and-a-half inches. If you have one of those soil types, you can probably get by watering less because the soil stays moist longer.

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Check soil moisture

To determine if your plants actually need to be watered, "a good rule of thumb would be to check your soil moisture twice a week by sticking your fingers into the soil near the root crown," says Todd Forrest, the New York Botanical Garden's vice president for horticulture and living collections. "Water only if the soil below the ground surface feels dry to the touch." (The root crown is where the stem meets the roots.)

Jeannine Bogard, horticulturist and president of the National Garden Bureau, suggests another quick way to know if your plants are thirsty: "If the soil color is light and it is dry to the touch, water."

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Water deeply and gently

Experts advise watering deeply for most established plants, shrubs and trees. "That is, watering less often but for longer periods of time, and the goal is to get that water deeper into the soil," says Stock. The deeper the water goes, the deeper roots can grow. The benefits are twofold: Deeper soil is cooler and deeply rooted plants are harder to stress out.

To better understand how the ground around your plants absorbs moisture, Bogard suggests thinking of your soil as a sponge. "A dry sponge will not easily absorb water and initially sheds the water. A damp sponge soaks up excess water," she says. "Ideally, you want to gently water the plants so the water has a chance to soak into the soil, rather than run off."

This is why water pressure is important. "The tendency is to turn the pressure up to get the job done faster, but using too-high pressure can damage the plants ... and the water just runs off, rather than soaks in," says Bogard.

There are some exceptions: "Small plants don't need deep watering, they need regular superficial water - for example, a lettuce plant," says Benjamin Eichorn, CEO and founder at Grow Your Lunch.

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Water around the bottom of plants

The roots of a plant need water, not the foliage - so you should water at the base.

Eichorn encourages gardeners to water around the outermost perimeter of a plant's base - beneath the widest part of the foliage - rather than directly where the stem emerges from the soil. "Healthy plant-root growth actually mirrors aboveground foliar growth," he says. Growing plants in pots? He suggests watering at the edge of the container.

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Water at the right time of day

Watering just before sunrise - typically the coolest, highest-humidity part of the day - minimizes evaporation, meaning it will take less water to do a thorough job. "Watering in the morning means that moisture is going to mostly soak into the ground," says Eichorn.

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Choose efficient watering tools

Using a drip irrigation system, setting up a sprinkler, or hand-watering with a hose all yield different results.

"Drip irrigation is our most efficient irrigation system," says Stock. "The water is getting delivered directly to the soil and maximizing where the water is going." You'll want to regularly monitor the system to make sure leaks or other problems haven't popped up.

While sprinklers are convenient and relatively inexpensive, they often require more water to get the job done. "In hot climates or dry climates where you're spraying water into the air, a significant portion of that water evaporates," says Tanner.

Sprinklers are even less efficient on windy days. Another of their disadvantages, says Tanner, is they get foliage wet, which can contribute to disease and other problems in plants.

Though hand-watering requires the most effort, it is often the least wasteful way to care for your garden, especially in the heat. "Hand-watering is ideal because you put water exactly where you want it, when you want it," says Eichorn.

When Bogard hand-waters her own yard, she says she spends five seconds watering the base of each plant, moving down the bed, then returning and repeating the process again. On hot days, she may repeat a third time.

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Use mulch

Mulching keeps moisture in the soil longer and helps plants stay cool - both of which allow you to water less frequently. "Think of mulch like a blanket," says Tanner. "In the summertime, it shields the soil from sunlight and prevents it from getting too hot." He recommends applying a two-to-three-inch-deep layer of mulch made of organic material, such as leaves or straw, around your plants.

Eichorn recommends placing the mulch slightly away from the stem and foliage of the plant. "If you want to discourage blight and mold, don't have [the mulch] touch your plants," he says.

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Don't count on rainfall alone

The general rule in warm weather is that a garden requires one to two inches of rain per week to be sufficiently watered without additional help, says Stock. But many other factors, such as your geographical location and soil type, can affect this.

To know exactly how much rainfall you get, consider adding a rain gauge to your yard. Also keep in mind that rainfall will not evenly cover your entire landscape, so pay particular attention to drier spots that may need an extra drink.

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