Trimming Bougainvillea After Frost Damage

Damage Seen

• Depending on the duration of the subfreezing temperatures, the bougainvillea reveals leaf and flower tissue damage within 24 to 48 hours. Leaf and flower bract edges might crinkle and brown if the frost was brief and light. Often, you should expect the plant to shed flowers and leaves as a result of the frost. Branches remain nude, and those with cold-killed tissues become dry and brittle. However, lower areas on the plant often remain alive with sap, and from these areas new buds arise and rejuvenate the bougainvillea with new leaves and stem shoots.

Time Frame

• Withhold all pruning and trimming maintenance on a frost-affected bougainvillea until the threat of all winter frost passes. This is usually referred to as the last spring frost date, and it varies across the United States, depending on latitude and elevation. Trim dry, brittle, dead branches on the bougainvillea only after the last spring frost date. You can wait longer, as the warming weather coaxes out new growth to reveal what parts of the plant are truly alive. Even if you trim in midwinter, the act of pruning itself does not stimulate regrowth. Only warm weather, sunlight and moist, fertile soil bring the bougainvillea back to life in spring.

Advantages of Waiting

• If your bougainvillea sustains frost damage in early winter, and there still is a possibility of more frost later in the season, it's better to withhold all pruning. While trimming the bougainvillea might make the plant look tidier, it makes the plant more susceptible to further cold damage. Keeping the plant intact the rest of winter ensures the outermost branches bear the brunt of cold. Pruning exposes lower living branch tissues to cold that normally would have been buffered. It's better to preserve lower branch and trunk tissue, because potential rejuvenating growth sprouts from these areas.

Procedure

• Wear gloves when pruning a bougainvillea, because thorns and prickly stem spurs grace the arching branches. Use a bypass or hand pruners to cut and remove dead branches that are less than three-quarters of an inch thick; loppers cut branches three-quarters to 1 1/2 inches in diameter. When green buds or leaves sprout in spring, cut back the upper dead branches to shape the bougainvillea, preserving all areas where growth is sprouting. Make the cuts one-quarter to one-half inch above the bud, leafy sprout or a lower living branch junction.