Water rights ... and wrongs - How to know what your plants and trees really need

Water rights ... and wrongs - How to know what your plants and trees really need
By Beth Botts
Copyright © 2007, Chicago Tribune
July 29, 2007


The gardening season means watering. But it shouldn't mean wasting water.

In fact, watering the wrong way can actually hurt plants. It also can waste money and exacerbate pollution.

But many people don't know how to water right or have never thought about it. Here are some tips for putting water only where it will do good. The Basics

Rule 1 for plants in the ground -- including lawns -- is this: Slow, deep watering at long intervals is better than watering often but lightly. A daily ritual of sprinkling flower beds with the hose in your hand makes plants grow short, weak, vulnerable roots right at the surface. A deep soak once a week encourages them to send those roots long and strong down into the soil. That makes plants more drought -- tolerant and more able to take up nutrients and support more leaves and flowers.

Overwatering can fill up the air space in soil and actually drown plants or cause roots to rot.

A rule of thumb is that most plants need the equivalent of 1 inch of rain a week (about .6 gallon per square foot). But many factors can affect this: Desert plants such as cacti obviously need much less. Established prairie plants, with deep root systems, need less watering than shallow-rooted, thirsty annuals such as impatiens. Get to know your plants and their needs.

Soil type makes a difference too. Water soaks right into sandy loam but easily runs off dense, clay soil. So observe how water behaves on your soil.

To measure rain or the output of sprinklers, buy a rain gauge (starting at about $3 at the hardware store). In fact, get two: One for the lawn and one to place under trees, where much less rain reaches the ground.

But the real criterion should be how much water is in the soil. Stick your finger in and feel for moisture (or dig down with a trowel). If it's dry 2 to 3 inches down, water.

Containers

Soil dries out quickly in pots. Check them every morning; for much of the summer you may have to water them once or even twice a day. Plastic or glazed containers lose water more slowly than unglazed terra cotta or moss baskets; small containers dry out fast. Self-watering containers, with hidden reservoirs, can help. Pots in sunny locations will need more watering.

Nozzles

* Buy heavy-duty metal nozzles with adjustable spray.

* Get a hose wand extension to water containers and hanging baskets.

Sprinklers

Sprinklers have drawbacks. They water foliage, not soil; much of the water they fling through the air or dribble on leaves evaporates uselessly; and they can rain water on sidewalks, patios and driveways, where it is wasted. However, sprinklers are the best way to distribute water over a large area.

Here are some tips:

* Water in the morning, so leaves dry in the sun. Wet foliage at night encourages fungus diseases.

* Have more than one sprinkler, so you can fit the watering pattern to different areas of your yard. A good assortment is an oscillating sprinkler, which waves back and forth over a rectangular area, such as a lawn; an impulse sprinkler, which flings water in a wide circle or part of one; and a pattern sprinkler, which can deliver a steady stream in several arrangements in tight spots.

* If a sprinkler does not have one, add a shut-off valve between it and the hose so you easily can reduce the water pressure to the area you need to water.

* In-ground sprinkler systems: Get a moisture sensor that only turns on the sprinklers when the ground is dry. Otherwise, learn to adjust the timer and turn it on and off as needed. Don't just leave it at the installed settings regardless of conditions; that's a huge water-waster.

Lawns

In summer, you can save water by letting the lawn go dormant. (Many leaves will dry and turn brown but each plant's crown and roots remain alive, waiting for cooler weather.) But decide to either let it go dormant or not. Don't try to revive it with heavy watering when it goes brown. A long soak every two weeks, or a good rain, will keep the roots alive.

* To keep grass green, water deeply once a week, no more often. Too much watering, or watering at night, can lead to lawn diseases and grubs.

* Mow the lawn high -- a good 3 inches -- to conserve water and encourage long roots.

* Don't fertilize in summer. Overfertilizing makes lawns weak and thirsty.

* Aerate the lawn every spring to help it absorb water.

Trees and shrubs

* New trees and shrubs, with struggling root systems, need watering for a year after they are planted. Turn the sprinkler on to just a dribble and set it on the root zone for several hours once a week. The following week, move it to a different spot.

* Established trees and shrubs rarely need supplemental watering except in drought, when they are sick or stressed or if they have a restricted root zone -- for example, hemmed in by house, path and driveway.

Water just the soil

* It's the roots that need the water, so the most efficient watering goes right to the soil.

* Soaker hoses are easy to set up; just lay them around in beds. But they must be taken indoors in winter.

* Drip irrigation is more finicky to set up, but can be left out in the winter. Start with a kit to get used to the parts and procedures.

Gadgets

Several devices make watering much easier.

* A two-way valve: Screw onto the faucet to give you two taps.

* Quick connectors: These allow you to quickly and easily swap sprinklers, nozzles and timers.

* Timers make it possible to water when you are not home.

Shut-off timers run the water for a certain time and then turn it off. (A flow meter is similar but measures gallons, not time.)

Electronic timers need batteries, but can be set to turn water on and off any time.