GARDENING : Take a Healthy Interest and Get to the Root of What Ails Plants

Do you have plants that look like they are about to croak? As summer heat intensifies, plants are frequently stressed by scorching temperatures, lack of water and attacks by sucking or chewing insects.

If you pay attention to the symptoms, you can often act in time to restore plants to good health. But it’s important to properly diagnose the ailment before reaching for a remedy.

For instance, yellow leaves in plants can be one of the first signs of trouble. They can indicate stress from dry soil, insect attack or even overwatering in conditions where heavy clay soil is saturated with water, preventing oxygen from reaching the leaves. But some plants are merely going through a natural cycle of dropping older leaves while replacing them with new, green ones.

To determine what if any problem there is, it’s important to dig for facts.

Wade Roberts regularly uses an eight-powered lens to search for signs of trouble. At Sherman Gardens in Corona del Mar, where Roberts is director, magnifying lenses are a routine gardening tool.

“All the staff and volunteers here are equipped with lenses,” he explained. “It’s amazing what you can see by studying the underside of plant leaves.”

A lens, whether the sophisticated type used by botanists or a common magnifying lens, reveals if insects are feeding on leaves and, if so, what type they are. This simple method of detecting is one of the first steps in nursing ailing plants.

Some insects can simply be washed off plants with the spray from a garden hose; some require a more concerted effort. If you discover damaging insects but are unable to identify them on your own or determine what to do, take a contained sample with you to a nursery or botanical garden for assistance.

“There really are only a handful of problems,” Roberts said. “Learn to identify what’s wrong with the plant before taking any action.”

He points out that often, in their zeal to correct the problem, people make it worse by jumping to the wrong conclusion and the wrong solution.

One of the most common problems plants and lawns endure in summer is overwatering or under-watering.

First test the soil to determine if it’s dry.

There are inexpensive soil probes available commercially, but many expert gardeners use an even simpler method: pushing a finger several inches into the soil to check for moisture. Use a trowel or shovel if you need to check more than several inches deep.

Watering daily as a summer routine is a waste of water and money and can cause even more problems. Most landscapes and container plants need to dry between waterings. Otherwise, soil fungi can attack plant roots.

Rico Montenegro, assistant director of the Fullerton Arboretum, advises paying attention to plants and landscape when they’re healthy so you can prevent problems.

“Know the overall appearance of your plants,” he urges. “Plants give signals before they start wilting, and the first is loss of color. A deep green plant looks duller. A lawn changes color and isn’t as resilient.”

Other summer ailments include improper fertilization and battering by Santa Ana winds.

“When plants are under stress, it’s important not to fertilize them, since that stresses them even more,” Montenegro counseled.

“The people who love their plants to death do that literally by overwatering and overfeeding them so they produce succulent, tender green growth in the height of summer.

“Then the temperatures rise or the winds start to blow, and these are the first plants to get stressed.”

Give your plant first aid. N2