A spectacular sight in the tropics and hot coastal areas of the Americas is the ever-blooming bougainvillea, a shrubby vine covered with bright and gaudy blossoms.
Named in honor of L.A. de Bougainville, a French navigator who lived from 1729 to 1811, the plant is native to South America. First described and classified in 1789, bougainvillea was discovered in Brazil twenty years earlier. Since their petals resemble paper, bougainvillea is popularly known as Paper Flowers.
Botanically, bougainvillea is classified as Bougainvillea Glabra, Bougainvillea Peruviana, or Bougainvillea x Buttiana (a hybrid of the previous two). Most commercial varieties are selections and hybrids of these three main species.
New hybrids appear regularly. The flowers we associate with bougainvillea are red, purple, pink, lavender, orange, white, and bi-color bracts. True bougainvillea flowers are small, white, and tubular, appearing inside these colorful papery bracts.
Bougainvillea cascading over a wall.
Usually, bougainvillea grows as thorny vines, but recent efforts have produced mostly thornless hybrids. Another trend is toward developing shrubby plants with more compact habits for container growing.
Light & Bougainvillea
Sunlight is probably the most critical factor in bougainvillea cultivation. Bougainvillea needs 3/4 to full sunlight — no less — or it won’t bloom. A common misconception is that bougainvillea bloom only during the fall, winter, and spring. Bougainvillea can bloom all year if grown correctly in good light. Cool weather may retard growth in the winter. A hot greenhouse will encourage new growth, which leads to repeat flowering.
Watering
NEVER let potted plants wilt during the blooming period or stand in too much water. Bougainvillea needs a “happy medium.” After planting in the ground, hold back on watering slightly until the bougainvillea begins to expand its roots — then water as necessary.
Fertilizing
A top-dressing with “ColorStar” bougainvillea fertilizer will get the growth off to a good start. Incorporating a well-balanced slow-release coated fertilizer into the soil at planting time will encourage growth and blooming for a long time. Too much nitrogen in the fertilizer will cause excessive leaf growth, leading to delayed or aborted blooming.
Iron is vital for good green color, but tends to be unavailable to bougainvillea plants during cold winter weather. Soluble, granular iron works well and, unlike sprays, won’t stain leaves and blooms.
Pruning Bougainvillea
Bougainvillea bloom on new growth. With proper pruning, sunlight, and water, plants will repeat a blooming cycle in about 4 weeks.
A rule of thumb is to prune, once the blooming is over, one-half of the growth ending in a bloom. For example, if the growth where blooming occurs has grown out 6 inches, prune off the old bloom cluster, plus 3 inches of the stem after blooming. Also, “pinching” the tips of your bougainvillea encourages new growth and flowers and maintains a compact, manageable plant.
Planting Bougainvillea
For winter protection of in-ground plants, mound or “bank” soil 6 inches over the roots and lower plant stems. Leave this all winter and allow the outer stems to freeze. Once the chances of freezing have passed in the spring, cut the plants back to this soil mound and wash the mound away, leaving the lower stems exposed.
A beautiful ocean view framed by Bougainvillea.
With steady light, warm temperatures, and watering, bougainvillea should begin budding in about 4 weeks. Keep potted bougainvillea plants out of 32 degrees and colder weather by moving them inside for the duration of freezing temperatures.
If the leaves burn from wind or frost, give your plant good warmth and light. It should begin growing back within 10 to 20 days and bloom in the expected 4-week time frame.
Pest Control
Aphids are the most common bougainvillea pest we encounter. Other common pests include:
- Leaf Miner
- Scale Insects
- Thrips
- Spider Mites
- Slugs and Snails
Natural control methods include:
- Introducing beneficial insects like ladybugs or lacewings to prey on aphids and other small pests
- Regularly spraying the plant with a solution of neem oil and water to deter pests like aphids, thrips, and mites
- Pruning affected areas and removing infested leaves to reduce pest populations
Disease Control
Common plant diseases affecting bougainvillea include:
- Bacterial and Fungal Leaf Spot: Prune affected areas and remove infected leaves immediately to prevent spread
- Mildew: Apply a fungicide when transplanting the plants to reduce chances of infection and prevent root rot
Natural control methods for these diseases involve:
- Using a mixture of neem oil and water (2 tablespoons of neem oil in 1 gallon of water) to spray the leaves thoroughly
- Regularly inspecting plants for early signs of disease and maintaining a clean growing environment to discourage pathogens
FAQs: Growing Bougainvillea
Q: How often should I water my Bougainvillea in Southern California?
A: Bougainvillea plants thrive with deep watering once every 3-4 weeks. They prefer dry soil between watering. During the hotter months, you may need to water more frequently, but ensure the soil has dried out before watering again. Over-watering can lead to root rot.
Q: Can Bougainvillea tolerate full sun in Southern California?
A: Bougainvillea are sun-loving plants and can handle the strong Southern California sun. They require at least 5-6 hours of direct sunlight daily to produce the best blooms. More sunlight often leads to a more spectacular display of flowers.
Q: What is the proper way to fertilize Bougainvillea in this region?
A: Fertilizing should be done during their blooming period with a high-phosphorus, water-soluble fertilizer to encourage flowering. Apply it every four to six weeks from early spring through mid-fall, following the manufacturer’s instructions.
Q: What type of soil is best for planting Bougainvillea?
A: Bougainvillea prefers well-draining soil, as it does not like ‘wet feet.’ In Southern California, use a mixture of peat, pine bark, and coarse sand for optimal growth. This combination ensures proper drainage and aeration.
Q: Is it necessary to prune Bougainvillea, and if so, when?
A: Yes, pruning is essential to maintain shape, encourage new growth, and maximize flowering. The best time for pruning is in early spring, after the last frost date but before the new growth starts. Always use clean, sharp tools to make smooth cuts.
Q: When is the best time to plant Bougainvillea in Southern California?
A: The ideal time to plant Bougainvillea is spring, following the last frost when temperatures rise. This season provides the plant with ample time to establish its roots before the onset of the hot summer months.
Q: Can Bougainvillea be grown in pots, and how should they be cared for?
A: Bougainvillea grows well in pots, which allows you to move the plant to optimal sunlight locations. Pots should have good drainage. Choose a pot that can accommodate the plant’s growth over time.
Q: How do I protect my Bougainvillea during a rare Southern California freeze?
A: On the occasional cold night, cover your Bougainvillea with frost cloth or burlap. Also, try to place potted plants in a sheltered area, like against a warm south-facing wall, or move them indoors if possible. Remove the coverings during the day to allow sunlight and prevent overheating.