Plants can be multiplied mainly by two methods. One is the sexual method and the other is the vegetative method. In the former method, generally two different parents plants are involved, leading to seed formation; eventually seed germination takes place. The second is the vegetative method in which different parts of the single parent are used to produce new plants. Seed germination in orchids occurs only in association with a special type of fungus. Further, seed grown orchids take very long to mature and bloom, sometimes as long as seven to eight years.
Contrary to this, orchids can be quite easily propagated vegetatively. The success rate of vegetative propagation is much higher and the new orchid starts to bloom early. The maturity of a vegetatively grown orchid is decided by the maturity stage of the parent plant.
There are different ways of vegetative propagation. In case of orchids like the Bulbophyllums or the Dendrobes, each stem possess roots. You can separate these from the parent plant and plant them as a new plant. But take care that the stem bears sufficient leaves for food preparation.
Orchids can be grown through cuttings taken from mature plants. Sometimes orchids produce aerial roots along the exposed stem at the nodal region. These stem portions (bearing roots) when separated (hygienically!), can easily grow as a separate individual.
Using backbulbs is another way to divide orchids having bulbs. What do you understand by backbulbs? These are actually the previous growing seasonís bulbs. When the flowering season passes, the stem shrinks and eventually falls off leaving behind the bulb. These bulbs bear very tiny shoot buds hidden under the nodal scales, from which new offshoots grow out in the next season. After the stem falls off the bulbs enter resting phase, so these can be stored in sand with occasional watering, taking care that rotting does not set in. Once the next growing season starts, plant the bulbs in the appropriate growing medium. New growth will soon be seen sprouting out. I once multiplied Eria by placing the backbulbs on coconut fibres, inside polythene bags. After blowing air into them, I closed the top of the bags with thread. Exchange of gases was facilitated through tiny punched holes.
Sometimes tiny plantlets can be seen sprouting out at the base of orchids, these are referred to as kiekies. These kiekies can be carefully separated from the parent orchid and planted in a new pot/basket; taking care that the kiekies are sufficiently grown.
The above mentioned methods of multiplication require very little extra cost, if any. There are methods of propagation, however, which are costlier. These include various tissue culture techniques by which we can produce new plants, using different vegetative parts like stem, leaves etc. Mericlones are also produced through tissue culture. Another technique of propagation through tissue culture is generation of artificial seed capsules.
Disadvantage of the vegetatively multiplied orchids is that these are more susceptible to disease attacks as a group. So if any one of the cloned orchid gets infected, it can very quickly pass the infection to others of its kind. Remove it immediately.
Both methods of propagation have advantages as well as disadvantages; depending upon your resources, you have to decide which method to follow.