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.
It is sturdy, hardy, beautiful, has a heavenly fragrance and a long vase life of about two weeks. Tuberose can be successfully grown in practically all types of soils, even in acidic or alkaline soils to some extent. It can be potted and grown indoors as well, especially in colder climates. The plant is quite sensitive to water-logging which may damage the root system. Loam and sandy loam soils with a pH range between 6.5 and 7.5 with proper aeration and drainage are best for tuberose cultivation. The soil should be rich in organic matter (excellent results with 10 to 12 tons of FYM per hectare) and retain sufficient moisture (mulching is advised in areas where soil tends to get dry) for proper growth.
The bulbs that are 2-3 cm wide (size 6/8) are suitable for propagation. Larger bulbs result in early flowering and higher yields. Bulb size is given as up to 6, 6/8, 8/10, 10/12, 12/14, 14/16 and 16+. The numbers indicate the circumference of the bulb in cm at its widest part. So, a bulb of 10/12 size would indicate a bulb with a circumference of between 10 and 12 cm. The rhizome can be planted as such or cut vertically in two or three sections such that each segment contains a bud for germination. The bulbs should be planted 4-5 cm deep in beds and soil moisture should be maintained after planting of bulbs.
Flower production varies with cultivar and depends upon bulb size at planting time as well as the spacing between bulbs. Tuberose is planted at a spacing of about 30 cm x 30 cm with a plant population of approximately 100,000 plants per hectare. Commercial growers dig out larger bulbs about three years after planting. The tuberose needs warmth, plenty of water while growing, and rich, well-drained soil.
Apart from farm yard manure (FYM), a fertilizer mixture containing 6 g of urea, 16 g each of superphosphate (single) and muriate of potash per square meter has been found to show good growth and flowering. The above mixture should be applied in two equal doses the first dose before planting and the second, four weeks after sprouting of the bulb. Weeding should also be done regularly, though once the tuberose takes root and leaves begin to spread out in clumps, the chance of growth of weeds or grass between the flower clusters is automatically checked to a large extent. With the kind of fertile soil we have in the Gangetic plains, tuberose has really proven to be a no-fuss plant that requires very little special care.
As a grower, if you think of growing the flowers it would be an excellent one-time investment, with an output that far exceeds the input. Due to its commercial viability, all year round flower yield, sturdiness and hardiness, tuberose is grown as the anchor crop at GoGreen Farms. If you are a grower, once you buy the bulbs, with a bit of good management, you can continue to prepare your own marketable bulbs from the seed stock.
GoGreen farms is a grower, supplier and exporter of cut flowers, bulbs and corms.