Vining shrub a visual delight, but requires extra work

Angela O'Callaghan

Thursday, Sept. 18, 2008 | midnight

One of the loveliest vining shrubs for warm climates is bougainvillea. With its cascading habit and vivid blossoms that have colors ranging from fuchsia to bright red to purple, it makes a powerful visual impact. No wonder that so many people want it in their gardens!

It is commonly found in Arizona landscapes, but here in Southern Nevada it is less abundant. There are good reasons for this, since the intrepid gardener who wishes to succeed with this native of coastal Brazil needs to take extra care.

A few traits make bougainvillea a possible addition to our gardens. For one thing, it is generally tolerant of salt. Southern Nevada soils have the unfortunate tendency to contain high levels of salt, which is the residue of the ancient ocean that once covered this terrain. Many otherwise desirable plants suffer from salt burn when they are grown here. Not only is it salt tolerant, but being from the tropics it appreciates warm weather, another reason for its possible inclusion in local landscapes. While it requires deep, regular watering during its early development period (in particular, its first growing season), once it is firmly established in the soil, it is moderately drought tolerant. It is often grown as a bushy vine trained on some kind of trellis, which protects it from the gusty winds plants must endure.

While all of these characteristics might lead one to think that bougainvillea could be the ideal plant for this desert, it is not. The Mojave is not like the Sonora, nor like tropical Brazil. In this part of the world, heat and dry conditions are not the only determining factors. Among the challenges gardeners face here are salty, infertile soil, high summer temperatures, strong winds, a paltry amount of precipitation and the winter.

The southern Nevada winter might not be anything noteworthy in comparison to that of Maine or Minnesota, but it can definitely get cold enough to cause great damage to tropical plants. These vines, shrubs or herbaceous plants evolved in an area where frost does not occur. When temperatures drop well below freezing for a sustained length of time, the plants can be killed.

Fortunately, it is not a hopeless situation for gardeners who are intent on having bougainvillea's fabulous display. A certain level of commitment and work can improve the plant's chances of survival through most of our winters. About every ten years, the temperatures remain in the freezing range for an extended period. This can kill off many tropicals, but most of the time, that is not the case.

Make sure that the plant is protected from the fiercest (and coldest) winds. Plant it when soils have started to warm up in early spring. Make sure that the soil is covered with organic mulch. If it has the chance to become well established before the onset of cold weather, it may die down to the ground in winter, but emerge phoenix-like in the spring.

­Angela O’Callaghan is the area specialist in social horticulture for the University of Nevada Cooperative Extension. She can be reached c/o the Home News, 2360 Corporate Circle, Third Floor, Henderson, NV 89074, or [email protected].