Vine
Bougainvillea
Bougainvillea spectabilis · Nyctaginaceae
Also called: Paper Flower, Bougainvillea
Bougainvillea (Bougainvillea spectabilis) is a low-water vine well suited to Tucson and the low desert. It thrives in full and reflected sun.
Bougainvillea at a glance
- Water use
- Low (established)
- Sun
- Full and reflected sun; accepts the hottest exposures (south/west walls). Needs heat and sun to bloom heavily; shade reduces flowering.
- Mature size
- Vine/sprawling shrub to about 15-20 ft (some forms 15-40 ft); compact and shrub cultivars stay 3-6 ft. Trainable on walls, fences, and trellises.
- Growth rate
- Moderate to fast (vigorous; can grow several feet per season once established)
- Bloom
- Magenta, purple, red, pink, orange, white, and bicolors (the color comes from showy bracts surrounding small white true flowers), Spring through fall; year-round in frost-free conditions. Heaviest bloom in warm months; flowering pauses in cold winter weather.
- Cold hardiness
- Frost-sensitive in Tucson; root-hardy to roughly 25-28 F but top growth is damaged by frost (foliage burns around 32 F, with damage beginning near the upper 20s-low 30s). Plant in a warm microclimate (south/west wall), and protect or accept dieback in hard freezes. 'Barbara Karst' is among the most cold-tolerant cultivars for our area.
- Soil
- Tolerates poor, rocky, alkaline desert soils as long as drainage is excellent; dislikes wet, heavy soil. Disturb the brittle, sensitive root ball as little as possible when planting.
- Native range
- Brazil / tropical South America. A widely grown ornamental in the low desert; not native to the Sonoran Desert.
- Best used as
- Walls, fences, and trellises (trained as a vine), Hot-exposure screening and slope cover, Patio and entry color, Large containers (allows winter protection), Espalier
- Wildlife
- Attracts bees, butterflies, and hummingbirds to its bright bracts; dense thorny growth offers cover and nesting sites for birds.
- Toxicity
- Considered low toxicity / essentially non-toxic if ingested, but the large thorns can cause puncture wounds and the sap can cause skin and eye irritation or dermatitis. Keep thorny growth away from walkways and pets/children.
How to grow Bougainvillea in Tucson & the low desert
Watering
Plant in late spring once frost danger has passed and soil is warm, so it establishes before winter. Once established, water deeply and infrequently and let soil dry well between irrigations: roughly weekly in the hottest months (e.g., a long drip soak) and only about monthly in winter. Slightly stressing the plant (drier soil) actually triggers heavier bloom; overwatering causes lush growth with few flowers.
Fertilizer & nutrients
Feed in spring and summer during active growth with a bloom-type fertilizer (higher phosphorus, e.g., a 'hibiscus' or bloom-booster formula) or an iron supplement if leaves yellow; avoid high-nitrogen feeding, which favors foliage over flowers. Stop feeding in fall.
Pruning & care
Prune hard after the last frost in spring to shape and remove cold-damaged growth; tip-prune through summer to encourage flushes of bloom (flowers form on new growth). Wear gloves and eye protection: large thorns and irritating sap. Avoid heavy pruning in late fall.
Notes
One of the signature heat-loving, low-water ornamentals for Tucson: plant in late spring on a warm wall, water deeply but sparingly, and keep it slightly dry to maximize bloom. Its main limitation is frost, so site it in a protected microclimate or be ready to cover it (or grow a hardier cultivar like 'Barbara Karst'). The brittle roots are sensitive, so plant carefully and minimize root disturbance. Drops considerable bract/leaf litter.
Sources: AMWUA (amwua.org/plants/bougainvillea); University of Arizona Cooperative Extension / Pima County Master Gardeners; Water - Use It Wisely (wateruseitwisely.com); Arizona Daily Star / tucson.com horticulture column