Bougainvillea is a fast growing, woody, evergreen, thorny, multi-stemmed, ever-blooming climbing shrub, writes N. Chandramohan Reddy

They are here, there, everywhere. Tempering the grumpy black tar from the avenue margins, flowing over the unyielding high walls, these effusive whites, pinks, yellows, magentas, purples, violets and reds often splash the earth beneath in ultrathin hues. If anything stops them from being admired by a common man, it is solely their abundance. Bougainvillea is truly the Cinderella of our backyard! Yet, one would be surprised to know that the plant is not the native of India. Bougainvillea, though originating from South America, is a popular ornamental plant grown in warm climates throughout the world.

The Genus Bougainvillea, from the taxonomic family Nyctaginaceae, has about 14 species, among which three are important in terms of horticulture - Bougainvillea spectabilis, Bougainvillea glabra, and Bougainvillea peruviana. Crosses among the various species have produced new hybrids making available numerous cultivars with a striking array of colours. Single and double flower forms too are available.

Characteristics

Bougainvillea is a fast growing, woody, evergreen, thorny, multi-stemmed, ever-blooming climbing shrub. It climbs by sending out slender arching shoots armed with stiff thorns. Bougainvillea is deciduous when grown in areas with a long dry season.

Leaves are simple and alternate. They are mid green to deep green, though some cultivars have variegated foliage.

Actual flower of the plant is small, tubular, commonly white or yellow, but each cluster of three flowers is surrounded by three or six papery bracts (hence the name paper flower!) in bright colours. The bracts of many cultivars change their colour from emergence to maturity. They retain their colour for several months after the flowers have finished, fading away gradually.

Bougainvillea grows best in full sun. Low light and shady areas are not suitable, and make the plants drop their bracts. The plant does best at elevations from sea level to 2,500 feet, and grows well in rich, well-drained soils. This drought tolerant plant does not thrive in soil that is constantly wet.

Gardening

Bougainvillea’s growth habit and beautiful showy bracts make it a popular plant for gardens. It is used in mass plantings, as shrubs or bushes. For large, difficult-to-maintain areas, bougainvillea is an excellent ground cover. It can cover a whole hillside and will control weed growth. It can be trained into various shapes and makes good Bonsai.

Bougainvillea can be trained as a “standard,” a small tree with a single trunk, or over arbours, onto walls, or to cascade down a slope. It is also used as hedge or barrier plant, as a specimen plant, in hanging baskets and in containers. Generally Bougainvillea is planted a little away from the walkways to prevent anyone being scratched by the thorns.

Maintenance

For profuse flowering in Bougainvillea, one must avoid overwatering, total shade, heavy fertilising with nitrogen and frequent pruning.

Bougainvillea tolerates drying, and irrigation should be adjusted accordingly. Yet, they should not be allowed to dry completely. Avoid planting in the lawns. Don't put a bougainvillea next to a pool since it would necessitate frequent cleaning. Organic fertilizer amendments or controlled-release fertilizers should be used to moderate nitrogen release. At planting, amend the soil with a fertilizer high in Phosphate. Excessive fertilizer will promote vegetative growth and inhibit blooming.

Trimming & Pruning

Unless planted to cover larger areas, Bougainvillea will need periodic trimming. Caution should be exercised while pruning as they have stiff thorns, hence difficult to handle!

Bougainvillea responds well to pruning. If not pruned regularly, bougainvillea grows into a tangled mass. Flowers are borne on new growth, so pinching and pruning is necessary to induce new growth.

Too frequent a pruning could also inhibit flowering. Hence, it should be done once the flowering is finished, as this encourages new growth on which the next flush of flowers will occur. Suckers from the plant’s base should be pruned to encourage top growth. Dead wood should be removed as it appears.

Timing of flowering

Bougainvillea will flower profusely in high light intensities, moderate temperatures, and longer nights. Shorter day enhance flowering. Heavy shade inhibits flowering. Drought stress can stimulate flowering even under long day lengths. Allow plants to dry just to the point of wilting to induce flowering.

Pot culture

Container plants should be placed in bright light or near a window. In low-light indoors, their need for good sunlight leads to leaf drop. The medium needs to be well drained.

Plants should be watered when the medium surface becomes dry. Profuse, but not-so-frequent watering is better than frequent, sparse watering.

Prune young plants to encourage a framework of strong shoots emerging from the base. Prune and shape plants after they flower, maintaining a height of about three feet.

Propagation

Bougainvillea can be easily propagated through stem cuttings. The cuttings should be thick and have at least three to five nodes. Use a well drained rooting medium. Insert cuttings 1–2 inches into the medium and water thoroughly. Cuttings may be rooted directly in pots. Till rooting occurs, the pots may be kept in semi-shade so as not to let the plant wilt.

Rooting time is about one to two months, depending on the variety. Fungicide application at the time of planting and again after transplanting helps prevent root rot. Bougainvillea can also be propagated through leaf-bud cuttings and grafting. Also one can have blooms of many more colours in a single plant by grafting lef-buds of different cultivars to the same plant!

Pests and diseases

With appropriate cultural practices, Bougainvillea plants are pest free and disease resistant. But very rarely they may suffer from the insect pests like aphids, caterpillars, scale insects, thrips and white flies. The common diseases are leaf-spots and root-rot. These problems can be overcome by application of insecticides or fungicides, in minor doses.

(The author is a forest officer and can be contacted at ‘nchandramohanreddy@gmail.com’)