How to Trim Oleanders in the Southwest

Trim oleander in spring or wait until immediately after the flower display ends.

Wherever winter temperatures do not drop below 10 degrees Fahrenheit, summers are warm, soil well-drained and sunshine plentiful, you can grow oleanders (Nerium oleander). Tolerant of heat, drought and limited subfreezing temperatures, oleanders begin to bloom in March across the Southwest, depending on the onset of spring's heat. Trimming these woody evergreen shrubs, which mature 5 to 20 feet tall depending on cultivar, may be done in spring or summer.

Things You'll Need

• Gloves
• Bypass or hand pruners
• Loppers

Instructions

1. Wear gloves to protect your hands or if you have sensitive skin, because the sap of oleanders contains toxins that may cause a rash or irritation. Wash your hands to remove sap before touching others, eating food or touching your face, especially near your eyes. Oleander sap, even if diluted in sweat rolling down your brow, will severely burn your eyes.

2. Remove dead or broken branches of oleander any time of the year in the American Southwest. Use bypass pruners to remove branches less than 3/4 inch thick and use loppers for branches with a diameter between 3/4 and 1 1/2 inches.

3. Trim back oleander branch tips across the shrub in mid to late spring, immediately after the main flush of flower clusters subsides. Make the pruning cuts 1/4 to 1/2 inch above a lower branch junction, alive leaf or bud, on the lower naked branches. New growth and more flowers result four to eight weeks later, across summer and into the autumn.

4. Hand prune branch tips on the oleander; do not use shears, which will leave blunt, cut wounds on the evergreen foliage. Focus hand pruning on errant branches, branches that grow inward across the center of the plant, and upward or outward branching structures that spoil the shrub's symmetry

Tips & Warnings

• Trimming maintenance on oleanders may extend into the heat and drought of midsummer in the Southwest. Aim to finish up any trimming by the end of August. That gives ample regrowth time before the onset of potentially damaging first frosts by midautumn.

• If winter cold damage occurs on oleanders in the Southwest, postpone trimming or harsh rejuvenation pruning until a time in late winter or early spring, when frosts are no longer expected.

• Do not compost or burn trimmings from oleander. Discard of the trimmings in the landfill or in a separate pile where the decomposing toxins will not be absorbed by nearby edible plants. Smoke from burning oleander leaves and twigs carry the toxins in a noxious gas that can choke nearby people and animals.

References

• Arizona Cooperative Extension; Pruning Shrubs in the Low and Mid-Elevation Deserts in Arizona; Ursula K. Schuch; 2009
• "A-Z Encyclopedia of Garden Plants"; Christopher Brickell, et al., eds.; 2004
• Houston Chronicle: How and When Do I Prune Oleanders? Kathy Huber