GARDENING : Drowning in Good Intentions

The No. 1 cause of plant death is:

A) Lack of fertilization.

B) Disease and pest problems.

C) Over-watering.

The answer may surprise you.

The most common cause of plant ailment is not forgotten fertilizings or disease. It’s frequent shallow watering, says Steve Hollister, a California-certified nurseryman and manager of the Armstrong Garden Center in Irvine.

“Over-watering plants results in a number of stressful, potentially deadly problems, including shallow roots, root rot and salt damage,” he says.

Many of us have done it. A plant looks bad, and even though we just watered it, we figure a little more water might help.

“A lot of people tend to take too much care of their plants and do a lot of over-watering,” agrees Walter Lockhart, marketing manager for Decor America Inc., a Compton-based manufacturer of indoor and outdoor self-watering pots. “Then other people forget about their plants, which end up suffering from dehydration.”

Learn to water plants properly and you’re likely to be rewarded with a lush, healthy landscape. Proper watering generally also means using much less water.

The secret to proper watering is to water according to plant needs, not your own timetable, says Hollister. “Some people get into a watering routine according to the day of the week, but the only thing that should determine whether you water is the moisture level of the soil.”

You can’t base when to water on when you last watered. How damp or dry the soil is will vary from day to day and season to season.

When you water will also vary according to weather. When it rains as it has this week, nothing needs watering. But when the drying Santa Ana winds begin to blow again, some plants will need extra water.

“Go out and do some inspecting,” says Hollister. “Stick your finger into the soil about two inches, or open up the earth with a hand trowel and feel. If the soil is moist, the plant doesn’t need water.”

An inexpensive, easy-to-use tool to have on hand is a moisture meter.

“This is a metal rod which you stick into the soil, and it tells you if the soil is dry, damp or wet,” explains Paul Pirtle of Huntington Beach, who is a member of the California Organic Gardening Club. “It makes it quick and easy to check individual plants for moisture levels.”

The moisture meter, however, shouldn’t be be used for large trees, because their root systems run deep.

As a general rule, the larger the plant, the less frequent the watering. “Big, well-established trees may only need watering once every month or two during the dry season, and the same may apply to established shrubs,” says Hollister.

“Shallow-rooted plants like seasonal flowers will need watering much more often, sometimes two or even three times a week.”

To learn how to properly water, it’s also important that you understand Orange County soil. “The heavy clay soil we have here resists water penetration, so you must water slowly, deeply and infrequently,” says Hollister.

The worst thing you can do is what many sprinkler systems are set up to do and that is water rapidly on a frequent basis.

“Because clay soil is slow at accepting water, when you water quickly, the water doesn’t have enough time to penetrate the ground and it just runs off and is wasted,” says Gary Matsuoka, CCN, vice president of Laguna Hills Nursery Inc. in Lake Forest.

Another side effect of quick watering is shallow root formation.

“Watering frequently in small amounts forces the roots up near the surface of the soil where the water is,” says Hollister. Having shallow roots can stress and even kill a plant when conditions such as drying Santa Ana winds arise.

Inadequate, frequent watering also causes harmful salt accumulation.

“Our water is naturally very high in salt, which isn’t a problem if you irrigate plants slowly and deeply, because the salt is pushed past the root zone,” says Hollister.

When the watering is shallow, however, there is no escape for the salt and it stays and burns up the plant root system, which will also lead to above ground leaf burn and can mean eventual death.

When it comes to improper watering, lawns are often the most abused, says Hollister. “Although many people water their lawns every day, rarely does a lawn need watering more than three times a week and some more hardy grasses such as hybrid Bermuda and turf-type fescues can go a week,” he says.

If you have a sprinkler system that is watering your lawn daily or every other day for a short duration, switching to a longer soaking will take some adjustment.

To get your lawn to drink a large amount of water, set your sprinkler to run for five minutes three times, waiting an hour in between each application, suggests Matsuoka. “This will water the grass more deeply, prevent runoff and give you the same results with half the water,” he says.

Watering your grass in this manner only needs to be done a couple of times a week now and about three times a week during hotter weather. If you’ve been watering every day, you may want to gradually switch over. Go to every other day with increased duration and then go to every three days or so.

Keep in mind that these are watering approximations. The best way to know how much water your grass needs is to check its moisture level.

You can also prevent runoff by applying a wetting agent. This product causes water to better penetrate soil areas. Wetting agents only need to be applied a few times a year and make a dramatic difference in absorption, says Hollister.

Or aerate your lawn and other landscape areas with a sod coring tool. This cuts holes of earth, which you extract. Then you fill the holes with lawn top-dressing. “This gives the lawn air pockets so the roots can breath and enables the water to easily penetrate the ground,” says Hollister.

You can also make sure that your lawn gets all the water it has coming to it by watering in the early morning. When you water in the middle of the day, a lot of evaporation occurs and watering at night is not a good idea because long periods of wetness can lead to disease, says Hollister.

While sprinkler systems can be adjusted to water lawns and flowers, it’s more difficult to use them to properly irrigate trees, shrubs and gardens, which need less frequent, deeper watering. Because of variations in watering requirements, if you’re going to be automated, drip irrigation is the only way to go.

“Unlike conventional sprinklers, drip irrigation enables you to tailor how much water each individual plant needs,” says Hollister. Drip irrigation systems are composed of tubing with a variety of emitters that release water at varying rates and amounts, from one half gallon to four gallons an hour.

If container gardening is your thing, proper watering is also important.

To make sure that your potted plants get the water they need, try time-saving self-watering containers. These pots enable plants to drink from the bottom up as they get thirsty, a method extolled by European gardeners for many years.

“Watering from the bottom up is good for plants because you more or less give them control of watering,” says Lockhart, whose company’s self-watering containers are available in local home and garden stores.

Decor’s pots are designed with pillars at the bottom of the pot that are filled with soil during potting. These lead into a lower water well. As the plant needs water, capillary action draws water up through the soil directly to the plant roots. To water plants, you simply fill the water well every two or three weeks.

In the past, self-watering pots were hard to assemble, but new containers on the market such as Decor’s come fully assembled and are easy to use.