COLUMBIA, Mo. – Landscape plants are dying from heat and lack of rain.

Related radio news story by Debbie Johnson. For downloadable broadcast-quality audio, contact Johnson at 573-882-9183.

There’s so little moisture in the soil that without irrigation many homeowners will lose landscape plants. Even well-established trees are in crisis, according to Chris Starbuck, associate professor of plant sciences for University of Missouri Extension.

“At this point we’re starting to see trees that are 5 to 10 years old that are showing symptoms. That’s rare,” Starbuck said.

Conditions have become so severe that typical irrigation rules don’t apply.

“I think people should view this as a rescue mode,” Starbuck said. “I’d use a leaky soaker hose to get at least an inch of water over an area in a short amount of time.”

But a soaker hose doesn’t provide uniform irrigation. Most of the water leaks out before it reaches the end of the hose. There’s a quick fix for that.

Build an inexpensive drip irrigation system

Starbuck said it’s easy to build a soaker loop. Add a “gender bender,” an 8-inch piece of hose with two female ends, to one end of the soaker hose. Now both female ends will fit a Y- adapter.

The pressure coming out of most home water spigots is often too high for soaker hoses, which work best at less than 25 pounds per square inch. At higher pressures the water tends to shoot up into the air, where it’s wasted. Robert Schultheis, MU Extension natural resource engineering specialist, suggests adding an $8-10 in-line pressure regulator ahead of the Y-adapter. Now the soaker loop can be connected to a garden hose.

“Slowing the flow will make the soaker hose work more efficiently,” Schultheis said. “But it will increase the amount of time needed to get sufficient water into the soil.”

Time to do the math

It’s essential to add enough water to do some good, Starbuck said.

“Irrigating 1 inch of water requires about six-tenths of a gallon per square foot. So measure the irrigation area and multiply that by 0.62,” Starbuck said. “That will give you the number of gallons to apply to get an inch of water into the soil.”

Try this easy test to check the moisture in the soil.

“Push a screwdriver with an 8- to 10-inch blade into the soil,” Schultheis said. “The screwdriver should push in easily if you’ve added enough water.”

It’s important not to overdo it. Be careful not to drown small plants because you can kill your annuals, perennials and small shrubs with kindness by keeping their soil completely saturated when we have triple-digit air temperature, Starbuck said.

Act now or lose plants and trees

Concentrate on the most stressed trees and plants first.

“Wilting comes first, then leaf roll and scorch, then leaf loss and die-back. Start with those that are showing scorch,” Starbuck said. “If you can keep the roots from desiccating, the tree may survive to put out leaves next year.”

While this rescue irrigation will cost you extra on your water bill, Starbuck says the trees are worth it. They provide shade, keep energy costs down, remove pollution, absorb carbon dioxide and improve property values.

“If you have a large tree, that’s an investment. It’s a big asset in your landscape,” Starbuck said. “Trees are wonderful things and you want to keep them alive if you can.”

Waiting for rain is no longer an option.

“If we do that, people are going to lose a lot of trees, even trees that are 10 to 15 years old,” Starbuck said. “Bite the bullet, pay the water bill and rescue irrigate.”

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