Tropical Gardening: Warm summer days bring rampant growing shrubs and turf

East meets West at Lili‘uokalani Gardens in Hilo. The use of stone, water and spacious plantings of turf make for a pleasant ambiance. (Voltaire Moise/courtesy photo)
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Whether you have a home with a large yard or an apartment with a small lanai, plants create a more luxurious mood. Attractive trees, shrubs and lawns actually increase the value of a home.

In fact, if you cut down that big shade tree in the front yard, you may reduce the value of your property by thousands of dollars. Just think how much it would cost to have a landscape company replace it! When trees are destroyed, it affects the whole community.

The key to success is to put the right plants in the right place. Hot sunny areas of the islands require shady gardens to create a comfortable environment. Windbreaks are important to reduce excessive winds. Many tropical landscapes do not include grass. Examples may be found in books like “Tropical Asia Style,” “Thai Garden Style” and several books featuring the Hawaiian landscape.

Besides trees, shrubs and bedding plants, one of the main elements of many landscapes is ground covers including grass. It might be Bermuda, buffalo, centipede, zoysia, seashore paspalum, or a mix. Whatever type lawn it is, green and healthy is the key. It is important to remember that lawns generally require more maintenance, fertilizer and water than more deeply-rooted ground covers, shrubs and trees. Thus, many communities are minimizing turf except in parks and recreational areas like golf courses.

However, it is pleasing to see a healthy, well-maintained lawn. An expanse of green lawn can serve as the right setting for the homes they surround.

Artistically, lawns serve as the plain element in a garden picture, offering contrast of simple greenness to surrounding mixtures of color, texture and form in flower and foliage. This simplicity should be maintained by keeping the smooth sweep of lawn undisturbed by intrusions of shrubs and trees.

This does not mean that shrubs and trees may not be placed at strategic spots on the lawn. If carefully done, these may be used without disturbing the unity of the picture. But in general, it is best to keep the lawn uncluttered and unobstructed.

From a practical standpoint in the tropics, a lawn serves a number of ends. First, it reduces heat and glare as the sun beats down on the earth. Green is a soothing color. No doubt that is why there is so much of it in nature. Second, it controls mud and erosion. It definitely beats concrete, asphalt and gravel.

The chief value of a lawn over other kinds of ground covers is that it offers a pleasing place to walk and play, as well allows for artistic creativity. In a dry area, a grass like the many Bermuda varieties make a successful element, and can even be used for auto parking. Bermuda types do best in full sun.

A well-maintained grass cover also offers one of the easiest ways to control unwanted invaders. Just mow frequently and fertilize occasionally, making sure the grass cover has sufficient water to keep its green color.

Of course, if you want a perfect lawn that is a different proposition. Your idea may be just a green expanse to set off the surrounding landscape. Then it really does not matter of what the expanse consists. It may be a combination of grasses kept in check by frequent mowing.

Ordinarily, grass is not a good cover for steep sloping areas where it is difficult to handle the mower. In spots such as these, it is wiser to use ground covers and shrubs.

Large expansive lawns are a garden heritage from Europe. They are not typical in the Orient except through Western aesthetics. Much of Asian design uses moss, pebbles or sand for its plain element in landscaping. But in England, turf is key to the landscape and has become an essential part of the garden tradition.

Mainland Americans have inherited this tradition. They generally consider a lawn a necessary part of the landscape. However, in the wet tropics, turf is generally not a part of the native picture since meadows are infrequent. Here, it is a good idea to stop and consider whether or not a lawn is an essential part of your garden. In many parts of the mainland where water may be scarce and expensive, grass is fast disappearing as an aesthetic element.

Jungle effects with paths and patios tend to relate to the tropics more than do extensive lawns. And yet even here, there is much use of the lawn in open expanses around a dwelling.

A perfect lawn in the tropics is an expensive proposition. Golf course type lawns are not easy. To keep it perfect requires constant attention to weeding, rolling, fertilizing, mowing, watering and control of diseases. Just about the time you think you have everything under control, some new condition arises, and the lawn goes up in smoke.

Today there is a strong inclination to let the lawn be more informal along with the rest of the garden. Such a mixed green cover has its appeal, being more like a meadow than the monoculture lawn. A semi-natural lawn like this has its practical aspect also. It reduces maintenance by eliminating most of the weeding and also the struggle to make one kind of grass grow under the varying conditions of sun and shade which make up the average lawn area.

There is, no doubt, a legitimate reason for cultivating a green expanse around a dwelling even in the tropics. But let’s not make such a burden of it. When a weed pops up here and there, let it be. The secret is not in exterminating the weeds, but in keeping the area mowed so that the weeds cannot dominate and go to seed, keeping them from spreading too much.

Whatever type lawn you have, chances are it will require watering except in extremely rainy locations. Deep watering is preferred. Frequent shallow watering will encourage shallow rooting. It is best to water in the early morning. There is less waste of water through evaporation at that time.

Along with water, green growing things need fertilizer. This is especially true with the lawns. A fast growing grass like Bermuda may need fertilizer every month. On the other hand, zoysia may be fertilized two times each year or less. A slow release fertilizer high in nitrogen is usually the best.

For insect and disease control, your local garden supply dealer has several good products. Be sure to use the most environmentally friendly ones available and follow directions on the label.

The important thing is to think green. We humans have created too much desert in the past. The old saying, “Rain follows the forest, desert follows man” does not need to apply to wise Hawaiian gardeners!

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Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.