Shrub · Nyctaginaceae
Bougainvillea
Bougainvillea spectabilis
Run it hot, lean, and a touch dry, and bougainvillea repays you with sheets of color.
Full sun
Every 7–14 days
USDA 9–11
15–40 ft · 4.6–12.2 m
Overview
Bougainvillea is the source of those color-soaked walls that spill over fences and arches across warm regions. A woody, thorn-armed shrub native to South America, it will climb or scramble to 15 to 40 feet (4.6 to 12.2 m) where conditions favor it, yet stays tidy and small confined to a pot. The display you read as bloom is in fact a mass of papery bracts, the trait that earned it the name paper flower.
The defining quirk of this plant is that mild stress, not pampering, drives flowering. Treat it to rich ground, constant moisture, and generous feeding and you get a leafy green specimen with almost no color. Withhold instead, give it fierce sun and lean, dry footing, and the bracts come on strong from spring into fall.
Outdoor hardiness is limited to USDA zones 9 to 11, where killing frost seldom arrives. In colder regions growers keep it potted and shift it under cover for the cold months, an easy ask given its fast growth and tolerance of hard pruning. What never changes is the thornier truth, so count heavy gloves as standard equipment.
Care
The short version: give it unbroken sun, a fast-draining mix, and water only after the surface has dried. Feed sparingly, hold the nitrogen down, cut it back after bloom, and shield it from frost.
Light
Bougainvillea demands full sun, a minimum of 6 hours daily, and responds to even more. Shade is the fastest route to an all-green plant, because bract formation simply will not proceed without intense light driving it.
Water
Soak the root zone, then let the top of the soil dry before watering again, generally every 7 to 14 days once established. It is drought tolerant and flowers more freely on the dry side, whereas constant moisture pushes foliage over bracts and invites root rot.
Soil
Set it in well-drained sandy or loamy soil. It prefers a slightly acidic to neutral reaction, roughly 6.0 to 7.0, where micronutrients stay available, and it will not put up with ground that holds water.
Temperature
Heat is its element, and it copes with the full span from about 30°F to 100°F (-1°C to 38°C). Frost marks the hard limit, since freezing ruptures tissue, so anything below that point calls for cover or a move indoors.
Humidity
Average humidity is entirely adequate, and there is no figure to chase. Its needs center on strong sun and a dry root zone far more than on moisture in the air.
Feeding
Feed monthly from spring through midsummer with a balanced fertilizer at half the usual rate. Keep nitrogen modest, since a rich feed channels energy into leafy shoots rather than the bracts you are growing it for.
Pruning
Prune in late winter or early spring after flowering, and reserve any hard cutting back for after the bloom period closes so you do not sacrifice the coming display. Wear heavy gloves without fail, because the thorns draw blood.
Repotting
Pot on every 2 to 3 years or once it crowds its container. A tight, slightly pot-bound root ball is itself a mild stress that prompts flowering, so there is no advantage in rushing to a larger pot.
Size & spacing
With space to run, it climbs 15 to 40 feet (4.6 to 12.2 m) tall and spreads to match, so back a climbing specimen with a solid wall or trellis. Container culture holds it much smaller, and the dwarf cultivars are built for confined spots.
When to plant
This is a heat-driven plant with no frost tolerance, so wait until spring cold has fully cleared before setting it out. Once warm, it carries color from spring through fall, and in mild winters it may keep blooming past the season.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: after all danger of frost has passed in spring
- Harvest: spring through fall, sometimes into winter
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Nearly every bougainvillea complaint reduces to one of two patterns, missing color or shedding foliage, and culture rather than pathogens is usually the cause. Compare what your plant shows against the cases below and correct the conditions early, before a minor lapse leaves you with a bare, sulking shrub.
Leaves and bracts shed all together
An abrupt drop almost always trails a shock, most often a cold snap, a draft, or a relocation. Frozen leaves and shoots first look water-soaked, then turn black as the tissue dies. Hold it in one steady, warm, sunny spot, water it evenly, and pull containers indoors before readings near 30°F (-1°C).
Fix:
- Protect from frost and bring containers indoors before temperatures fall below about 30 degrees F
- Keep the plant in a stable location and avoid moving it
- Maintain consistent watering, avoiding both drought and waterlogging
Yellow leaves with the veins still green
When young leaves yellow while the veins stay green, the plant cannot draw up enough micronutrients, typically because the soil is too alkaline or stays wet too long, both of which lock those nutrients away. Keep it in slightly acidic, well-drained ground and let the soil dry between waterings. A foliar micronutrient spray formulated for citrus or palms restores green color.
Fix:
- Maintain slightly acidic, well-drained soil
- Apply a foliar micronutrient spray suitable for citrus or palms
- Improve drainage and avoid keeping soil constantly wet
Plenty of green growth but almost no color
A leafy plant refusing to color up has nearly always been treated too well. Bougainvillea flowers under stress, so dial back the water, give it at least 6 hours of full sun, and cut the nitrogen. Mild drought, plus a root ball that is a little pot-bound, tips it toward bloom.
Fix:
- Move to or provide full sun (6 or more hours direct)
- Allow soil to dry out between deep waterings and reduce watering
- Stop high-nitrogen feeding; use a balanced fertilizer at a reduced rate
- Allow the plant to become slightly pot-bound or stressed to encourage blooming
Notched, chewed leaf margins with dark pellets
The culprit is the bougainvillea looper, an inchworm-type caterpillar that feeds after dark and scallops the leaf edges. Inspect by night to catch it working, then remove the larvae by hand. Where numbers run high, treat young larvae with Bt or use spinosad, which takes out both young and mature caterpillars.
Fix:
- Handpick caterpillars, checking at night when they feed
- Apply Bacillus thuringiensis (Bt) to control young larvae
- Apply spinosad, which controls both young and mature larvae
Toxicity
Reassuring for anyone with pets or stock: this species has no documented toxic principle, so a bitten leaf will not poison a cat, dog, or grazing animal. The danger is mechanical. Rigid, sharp thorns arm the stems and can deliver puncture wounds, scratches, and occasional dermatitis, while the sap can irritate sensitive skin, so glove up before handling.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
With no toxic compound present, a curious cat that nibbles will not be poisoned. The genuine risk is the stiff thorns, which can rake a paw or face, so keep a potted specimen clear of a jumping cat's route.
Dogs None
Bougainvillea is safe for dogs to live alongside, and a chewed leaf carries no poison. A dog pushing through the canopy can snag a thorn, though, so watch for the occasional scratch or puncture rather than illness.
Horses Safe
Grazing does a horse no harm, as the plant holds no toxin. The sharp spines are the sole concern, since a horse leaning into the branches can take a puncture wound.
Rabbits Safe
A rabbit may eat the leaves with no risk of poisoning. Keep the thorny stems away from a small animal, where a spine could seriously injure soft skin or an eye.
Livestock Safe
Cattle, goats, and sheep face no toxic threat from this plant. The woody thorns are the thing to mind, since they can scratch hide or muzzle as animals browse through the growth.
Birds Safe
Birds perch and nest in bougainvillea unharmed, and no toxin is involved. The dense, spiny branches in fact offer small birds dependable cover.
People Safe
The plant poisons no one, but the thorns will wound. Their punctures and scratches can lead to dermatitis or, on rare occasions, a skin infection, and the milky sap may sting sensitive skin, so wear heavy gloves any time you prune or handle it.
Not chemically poisonous, but the plant has sharp woody thorns/spines that cause puncture wounds and scratches (rarely skin infection or dermatitis), and the sap may cause mild skin irritation in sensitive people. The physical thorns are the real hazard, not chemical poisoning. Wear heavy gloves when pruning or handling.
Varieties
The genus spans a broad range of bract colors and plant sizes, from tall climbers down to dwarf, container-scaled forms. The selections below are the ones you are most likely to meet.
Barbara Karst
A strong grower that produces vivid red to magenta bracts in heavy flushes.
San Diego Red
A widely planted large red selection valued for the sheer volume of its bloom.
Raspberry Ice
A compact choice carrying variegated foliage against rose-red bracts.
California Gold
Notable for warm yellow to gold bracts rather than the customary pinks and reds.
Pixie
A dwarf, naturally tidy form well suited to container culture.
Helen Johnson
A dwarf, compact selection that performs well in pots and hanging baskets.
How to propagate
Increasing your stock is not difficult, but it rewards patience, and cloning a plant you already have gives far more reliable results than starting from seed.
Stem cuttingsModerate
Summer · Several weeks to a few months
The standard route to new plants is summer cuttings. Take a length of current-season wood, set it into a sand and peat mix, and allow time, since rooting runs anywhere from a few weeks to a few months.
LayeringModerate
Growing season · Several weeks to months
Layering works well during the growing season: pin a low stem to the ground to root while it remains joined to the parent. Expect several weeks to months before the new section holds enough roots to sever.
SeedDemanding
Warm season · Slow and variable
Seed is workable in the warm season but slow and erratic, and the seedlings seldom resemble the parent. For that reason named cultivars are nearly always raised from cuttings or layers instead.
Myths
A bougainvillea's bright parts are its flowers.
Those vivid, papery petals are really modified leaves called bracts, not flowers in the true sense. The actual flowers are the tiny white or cream tubes seated at the center of each cluster, simple to overlook amid so much color.