Bougainvillea, a shrubby-climber is one of the most popular ornamental plants in tropical and sub-tropical gardens. This is grown all over the world mainly for its colorful bracts. Due to high popularity and intense use in tropical countries, Bougainvillea is called ‘Glory of the Tropics’.
In comparision to other flowering farden plants, Bougainvilleas are used extensively because of their colorful bracts available in a wide range of colors like white yellow, pink, red, mauve, bi-colored and multi-colored. Moreover, leaves of some of the varieties have unique variegation in vatious colors and combinations. The colorful and attractive foliage is also an added attraction particularly when the plant is out of bloom.
An easy adaptability of Bougainvilleas to different agr0-climatic conditions and free flowering habit has made them the obivious choice for every garden. A large numner of carieties are available in the horticultural nursery trade with varied growth habit and ideal for growing in the gardens for various purposes. No other plant can influence the landscapes and gardens in such an incredible way.
The plant is a native of Rio De Janerio, Brazil. Migration and introduction of Bougainvillea to India dates back to 1800. Initially it was confine to Calcutta and Bangalore. Subsequently, popularization and use of Bougainvillea increased gradually. Considering its horicultural importance in nursery trade, extensive R & D work was undertaken by the institutes under CSIR, ICAR and also at the State Agricultural Universities, since 1960 onwards.
Species and Varieties
Bougainvillea is a shrub or sometimes dwarf tree, often scan-dent, usually armed with simple or branched spines.
Species: There are 18 species but only four have horticultural importance due to their showy and colorful bracts. These species are B.spectabilis, B.glabra, B.x buttia-naand, B.peruviana.
Varieties: A large number of varieties are avialable all over the world. However, in horticultural nuresery trade the number of varieties available are limited.
Morphological characters are most imporatant for identification purpose which help in establishing identity of the variety. Both vegetative and floral characters are studied, recorded and interpreted in a scientific and standard manner. Each and every variety has got vertain diagnosis characters which differ from the others.
Culture, Planting and Management
Climatic Requirement: Bougainvilleas perform best under sunny and hot climate. Though they can withstand wide range of climatic conditions, growth and developemnt of bracts are affected under adverse conditions.
Soil: Bougainvillea can be grown in all types of soil. However, the soil should be well-drained and rich in plant nutrients. Slightly acidic soil having pH 6.0 to 6.5 is good for growth and flowering as it helps in the availability of micro-nutrients.
Site: A sunny location away from the shade of buildings and trees is best for Bougainvilleas. The development of color of the bracts is affected when planted in shade.
Planting Season: In eastern and northern India, planting can be done during February to April and subsequently in July to september. In southern India, planting can be done almost roung the year particularly when the temeprature is not very high and level of humidity is adequate.
Ground Planting: Method of planting – pits measuring 60x60x60 cm are prepared at the marked points and mixes with FYM in a 3:1 ratio along with neem cake @250 g/pit. Insecticides(Thimate 10G/Furadon 3G)@ 10 g/pit is also mixed with the soil before planting for controlling soil-borne insects. Planting distances depend on the purpose and usually are kept 2 to 3 m in between plants.
Manures and Fertilizers: Established plants should be manured twice in a year once in July and in February for encouraging growth and flowering. For best results, annual application of mixture of FYM) 5 to 7 kg), bonemeal(250 g), neem cake (250 g), superphosphate (250 g) and potash (50 g) per plant is recommended.
Irrigation: Young plants require watering at the initial stage for better establishment. Established plants in ground, however require less watering. Irrigation during pre-floweing and flowering stage is to be restricted which encourages profuse flowering.
Pruning and Training: The requiremnt of pruning and training depends on the use of the plant like hedge, cascafe, espalier, pot plant etc. If it is grown as climber on porch, arch, on stump, pruning and training becomes essential. Over grown, dead and de-shaped branches are required to be pruned preferably before monsoon or after the flowering. However, intensity and frequently of the pruning is dependent on the varietal behavior.
Planting in Pots
Pots/Containers: The minimum size of the earthen pots/cement pots should be 25 to 30 cm in diameter. Larger sized containers like cemet pots, metal drums, wooden tubs, barrels having diameter 50 to 90 cm are also used for growing specimen plants for display in large gardens..
Potting Mixture: The mixture should be prepared properly by mixing garden soil and FYM in 3:1 ratio together with Neem cake and bone meal @ 100 g/pot respectively.
Planting in pots/containers is done in moderate season of the year either in February to March or July to September.
Pruning and Pinching: Pinching of apical growth of the pit grown plants is also recommeded for encouraging lateral branches and mass flowering.
Manures and Fertilizers: In pot/container grown plants, application and forking of the manure mixture is recommended especially after pruning and during growth period. Therefore, blalanced application is recommended for overall best performance.
Irrigation: Young plants, in pots require regular watering till they are established. Frequency of irrigation is decided according to season. Overwatering should be avoided during flowering season as it may result into poor or lack of flowering.
Pruning: Pruning refers to the removal of vegetative part(main branch, sub-branch and shoots) of the mother plant. The main purposes of pruning are as follows.
- Removal of unwanted branches/twigs/shoots.
- To give the plant a proper shape depending upon the purpose.
- To encourage vegetative growth and flowering.
- Removal of broken and diseased branches.
Pest and Diseases
Bougainvilleas are very hardy and have strong defence mechanism. As a result, they are not attacked bu diseases and pests in large scale. However, there are some reports of minor diseases and pests which have been found affecting the plant occasionally. These can be controlled by spraying of systemic insecticides as and when required.
Bougainvilleas are generally propagated by vegetative means for large scale production of plants for garden use as well as nursery trade during various seasons depending upton the climatic conditions.
Stem Cuttings: A large member of varieties respond to stem cuttings and are easily propagated by this method.
- Hardwood Cuttings – In this method, stem cuttings with hardwood having diameter of 0.75 to 1.5 cm are selected for propagation purpose.
- Softwood with Leaf cuttings – Tip of the branches having softwood and a few leaves are selected as propagating material. The best performance of softwood leaf cuttings can be achieved in mist-condition.
Layering: Stems having pencil-thickness are selected for air-layering. The varieties which do not form roots in stem cutting are generally propagated by layering.
Budding: This is an alternative method of propagation but not done in large scale. Varieties which do not respond well by stem cutting are usually propagate by budding.
Grafting: This is relatively a new technique and is not a conventional propagation method for multiplication. The main purpose of grafting is to create novelty so that one plant may have bracts in multiple colors.