How Many Times Will My Oleander Bloom This Summer?

Known for its flowers' appearance and aroma, oleander (Nerium oleander) is a very popular low-maintenance shrub that blooms continuously as long as the conditions are correct. Hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10, oleander can add a dramatic splash of color to a yard, and, by giving the shrub a little attention, you can make the most of its growth patterns to enhance its blooming season.

Oleanders originated in the Mediterranean region, and the Nerium oleander species has been grown in Florida since the mid-1500s. Its various cultivars bloom in a wide spectrum of colors -- pink, yellow and white to purple, and the shrub typically grows 6 to 12 feet tall and wide but can grow up to 20 feet tall. Its 2- to 4-inch-wide flowers bloom from summer through fall. The flowering stops in autumn when temperatures turn cool, though the plant can bloom year-round in very warm climates. Its foliage is dark green, thick and leathery.

Oleander needs sunlight. If it is planted in a partially shaded area, it will bloom but may become leggy. Its soil should be well-drained, though oleander can withstand some excessive soil moisture as well as dry conditions. If the soil is dry, water it weekly to at least a 1-inch depth. The shrub can grow in most soil types and conditions -- even tolerating salt spray -- and thrives with a high soil pH, from 5.0 to above 8.3. Because of oleander's rapid growth potential, the plant's best use is as a screen or hedge.

Proper pruning can result in more flowering and a longer blooming season. Oleander flowers appear on new wood. So early spring is the best time for shaping the shrub by removing overgrown stems and growth that was damaged by winter's cold weather. During the summer and fall blooming season, prune the tips of stems below flower clusters after the flowers start fading to encourage new growth and buds. If you want to start over with your oleander, it should respond well to three-year regeneration pruning; cut off one-third of the old growth at the plant's base each year for three years, and maintain the new growth.

Because all parts of oleander are poisonous, use gloves when working with the shrub. Most of the toxicity is in the sap. So wash your skin thoroughly after contact with the plant. Do not burn oleander in a fire because the resulting fumes are toxic.

The shrub's most common pest is the oleander caterpillar. The caterpillar grows to about 2 inches long and is orange with black tufts of hair. Both the larva and mature caterpillar can decimate oleander foliage. Bacillus thuringiensis, known as Bt for short, is a natural pesticide that can be used to help keep the caterpillar under control.