Tuberose (Polianthes tuberosa) is an aromatic flower widely grown in the plains of India and blooms profusely during the summer and rains. The name reflects the fact that the plant is grown from tubers; hence, tuber-ose (and not tube-rose). Like gladioli these are tall flowers with stem length of 80 to 100 cm and spike length of 30 cm in medium size. The large size has stem length of 100 to 120 cm with spike length of about 40-45 cm. The stem contains waxy white flowers (Double Pearl) and pure white flowers (Single Mexican) borne in pairs along the spike. Apart from the flower and bulbs which have good commercial value, the essential oils extracted from tuberose are widely used in perfume industry. As its Indian name indicates “Rajanigandha” (rajani-night, gandha-fragrance) emits its enchanting fragrance all through the night.
The demand for tuberose bulbs and flowers is on the rise in the European Union which is the largest importer of tuberose bulbs. The countries that import the bulk of the tuberose bulbs are the Netherlands, UK, Italy, Spain and Germany, while Poland is a potentially upcoming market. Tuberose bulbs are in great demand in the USA also.
The two well-known tuberose varieties are Single Mexican and The Double Pearl. The former is preferred for its enticing fragrance, while the Double Pearl is preferred in flower arrangements due to the density of the flowers on its spikes. The Pearl also exudes fragrance characteristic of the tuberose, but to a lesser extent than the Single Mexican variety. Several Indian hybrid varieties are also widely grown. Notable among these are Rajat Rekha and Swarna Rekha in single flowered and double flowered tuberose respectively. In Rajat Rekha there are silvery white streaks along the middle of the blade, while golden-yellow streaks are there on the margins of the blade in Swarna Rekha (rajat meaning silver and swarna meaning gold in Hindi). There are other varieties also like Prajwal (Single) and Vaibhav (Double).
Tuberose is easy to propagate, requires minimum maintenance and yields flowers for about three years once bulbs are planted. The bulb size is graded in a similar way as in gladiolus. In India, with ordinary 6/8 and 8/10 size bulbs it is possible to harvest flowers regularly for three years with a single batch of bulbs. Large size bulbs are highly priced and in great demand. Since it is a rhizome, you can recover bulbs manifold and replant or sell them.
The bulbs remain dormant during the winter months in places where the temperature is low and if early planting is desired, the dormancy can be successfully broken by dipping the bulbs in 4% thiourea solution for one hour. Normally, tuberose begins to flower three months after planting of bulbs. It flowers mainly during the summer and rains (April-September) in India and from May to July on the hills; while in milder climate, it flowers well throughout the year. Harvesting is done from November through March in the Gangetic plains in the sub-Himalayan belt.