Bougainvilleas – cascades of colour
This old favourite can easily justify its popularity.
By Gerald Schofield.
Bougainvilleas were introduced to gardens centuries ago from South America, and today remain popular shrubs and climbers in many parts of the world. Their small, tubular, white or cream flowers are surrounded by colourful leaf-like bracts with a papery texture. It’s these bracts that adorn the plants with cascades of colour for months on end, especially after extended dry periods.
The colour range is wide and varied, from white to purple as well as shades of yellow, gold, orange, red, pink and lavender. Growth habits vary from dwarf shrubs with few or no thorns to large climbers sporting sturdy thorns on stout stems that can reach the canopies of large forest trees. Selecting the correct bougainvillea for specific purposes in the garden is of the utmost importance. Planting the wrong type in the wrong place can be a costly and frustrating exercise.
Bougainvilleas grow best in full sun and well-drained soil conditions. They can withstand light to moderate winter cold and frost but grow best in warmer subtropical climates. In dry or colder climates they lose all their leaves in winter, while in the more humid, milder parts they remain evergreen. Regular pruning in spring helps to keep them in shape and prevent rampant growth from getting out of hand. Pinching back new growth tips also assists in keeping bougainvilleas shorter and more compact. They’re largely pest and disease-free and easy to grow once plants are established. Drought and heat tolerance are two of their major attributes.
Thanks to their versatility and durability, bougainvilleas are used for numerous different roles or purposes in the landscape. Here are some of the ways in which these South American plants can make a difference in your garden:
Hedges and screens: They have been grown as formal clipped hedges or left to grow as a vigorous boundary screen for decades. Their vicious thorns add a security element to these types of boundary plantings.
Climbers on fences and trellis: Plants are easy to train up and across support mechanisms. A main arterial network of stems and branches needs to be tied to the structure. Annual pruning of excess growth right back to the framework of the plant keeps them in check.
Borders and edging: Low-growing shrubby types make good low, clipped borders in hot, subtropical climates.
Standards: Certain types make eye-catching standards. The stems need to be supported by a stout stake to be able to hold up the weight of the top growth. Annual pruning in spring keeps the plants in shape and prevents them from becoming top-heavy.
Pots and containers: Many of the more compact, free-flowering varieties are grown as outdoor pot specimens. They’re invaluable for lending colour to hot patios, courtyards and pool surrounds. Pinch back new growth tips to keep plants more compact and bushy.
Hanging baskets: Yes, they grow in baskets too! Large baskets growing in full sun can be filled to perfection with some of the smaller cultivars like B. ‘Tropical Rainbow’ and B. ‘Temple Fire’.
Bonsai: Old plants produce thick, gnarled stems ideal for training into perfect flowering specimens in this age-old Japanese art form.
Questions and answers
Question: I read an article that recommended that bougainvilleas should be planted with their pot or nursery bag still attached to the root ball. Is this true?
Answer: All bougainvilleas have rather fragile root systems, especially young plants in nursery bags. Removing the pot or bag prior to transplanting can damage the taproot causing the plant to wilt or in some cases to die. Therefore it’s recommended that slits are made in the plastic bag to allow new roots to grow through. Then simply plant the bougainvillea ‘bag and all’ into the ground or larger ornamental pot.
Question: A friend of mine told me not to feed or apply fertiliser to bougainvilleas as this stops them from flowering. Is there any truth in this statement?
Answer: Like all plants, bougainvilleas need nourishment to grow. Apply a high-potassium fertiliser like 3:1:5 slow-release nitrogen as a soil dressing in spring, summer and autumn (three times a year). This promotes strong healthy growth and encourages flower bud set. When weather conditions are suitable (dry) bougainvilleas burst forth into bloom.
Question: I had a bougainvillea in a pot that was looking magnificent but all of a sudden the leaves wilted, turned brown and fell off the plant. What could cause that to happen?
Answer: Bougainvillea roots are escape artists that somehow find a way out of drainage holes in the bottom of pots they’re growing in. This promotes a sudden spurt of new growth due to the additional water and nutrients that they are exposed to. When the escaped roots are severed or damaged by wind or physical movement of the pot the plant loses condition instantly. In order to help save the plant prune back hard and keep the bougainvillea well watered until new growth has started.
Bougainvilleas are often said to be aggressive plants and some definitely are. But there are multitudes of magnificent hybrids and cultivars with a top-class garden performance that makes them splendid garden plants that can cope with the ever-changing climatic conditions. They survive wet and damp periods and thrive in dry times. What more can we ask of a garden plant?