This Is the Best Tool You Can Have for Watering Your Garden

Watering can: old but still effective.
Watering can: old but still effective. (Courtesy Of Haws Heritage)
Adrian Higgins
Thursday, August 23, 2007

I have found myself watching the weather maps in the hope that a great, swirling cotton candy monster called a hurricane will come my way.

Not as a devastating storm, but something weakened and wet that will sit over the mid-Atlantic and quench the thirst of prized garden plants parched from a summer of dry heat.

Two, three or four inches of rain should do it. That may prevent further needle drop from the dawn redwoods, perk up the flagging viburnums, top up the lily pond and get the stunted ornamental grasses to burst forth, finally.

Storms are hit-or-miss, so I keep a screwdriver handy. This simple household tool is perfect for measuring how wet the soil is after the gardener or Mother Nature irrigates it. In spite of a slight break in the weather pattern this week, that chore has fallen to the gardener this summer. A screwdriver will descend cleanly through wet soil but will not penetrate the dry level beneath. If you can get the shaft to sink four inches, you have done a good job of watering, and you can then leave an area alone for a few days or more.

Achieving good soil saturation takes a variety of watering techniques, some better than others.

Automatic irrigation systems have their place, especially for people who travel a lot or have gardens at second homes. I fear them for reasons beyond their cost, which can be formidable. I have seen them kill plants by overwatering. Moreover, they tend to take the human out of the equation, enticing us not to check on our plants and enjoy them, which seems to defeat the purpose.

If you want irrigation on the cheap, hook up a soaker hose to your garden hose. The hose has thousands of pinholes, and the water oozes out slowly over several hours. In theory, this seepage delivers moisture to plant root zones in an efficient way.

In my experience, soaker hoses are fine over short distances and on flat ground. They work well on certain vegetable crops that are in the ground for much of the season, such as tomatoes, peppers and squash. But string two or more 50-foot lengths together and employ them over hilly ground, and you will be disappointed. Water will seep from the first few feet but offer a mere teardrop or two farther from the spigot.

Here's a fact to impress your friends: For every 2.3 feet a hose rises, the internal water pressure drops by one pound per square inch. "If you start on low ground with 10 psi and go up around five feet, you're going to have 8 psi," said David S. Ross of the University of Maryland's Department of Environmental Science and Technology. "That's a 20 percent variation in pressure there."

A more refined version of the trickling hose is found in a drip-irrigation system. Water, pressure-regulated and filtered, is sent to a pipe that feeds emitters -- small lengths of mini-hoses positioned to deliver water to individual plants.

Produce growers use these beneath plastic mulch as an effective way of defeating summer droughts like this one. The plastic traps the moisture and prevents weed competition. The same system would work as well for homeowners but would need to be put in place at the start of the season, in May, and would not be suited for a lot of root vegetables such as carrots and onions. Also, this setup requires a raised bed to prevent rainwater puddling on top of the plastic mulch, said Jerry Brust, another agricultural expert at the University of Maryland.

If you didn't want to fuss with the plastic, which needs pinning in place, you could use a straw mulch. But Brust recommends a thick four-inch layer because weeds love drip-irrigation systems and would quickly smother your desired plants. Drip irrigation also works in ornamental beds, but the difficulty there is that if you are constantly planting and replanting them, as I am, you would live in fear of slicing through the lines.

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