There are two groups of propagating orchids; asexual (vegetative propagation) and sexual (seed and embryo culture).
Asexual or Vegetative Propagation
Vegetative propagation can be done in any of the following methods:
- Division – Cattleya, Dendrobium, Paphiopedilum and Cymbidium can be multiplied through division. Separate three to four canes or bulbs from mother plant to form new plants by cutting through rhizome and pot them individually.
- Formulation of Keikis and offshots – occasionally, a bud will give rise to a young plant at the top, side of pseudobulbs, canes or at the nodes of flowering stem. The Hawaiians call these young plantlets from vegetative or flowering stem ‘keikis’. Filipinos call them ‘anak’. Once the young new roots develop, remove plantlets and pot separately.
- Top cutting – monopodial orchids, such as Vandas, Ascocendas, Arachnis, Renanthera, Trichoglottis, and even Phalaenopsis and Doritis, are best propagated by top cutting. When plant becomes leggy, cut off top part, retain few roots and pot it separately. New roots develop readily by top cutting.
- Tissue Culture – Tissue culture is one of the most rapid methods of multiplying vegetative plant. It develops new plants in an artificial medium under aseptic conditions from very small parts of plants, such as shoots tip, root tip, pollen grain. Thousands or even millions of identical plants can be produced from a small tissue in a relatively short time.
Sexual Propagation or Seed Embryo Culture
Orchid sexual propagation is done through seed embryo culture. Orchid seed is so minute, devoid of stored food for seed germination. However, during germination, fungi infect orchid seeds and help convert complex starch to simple sugars, which serve as energy source. That fungi and orchids have symbiotic relationship during germination.
Under artificial or laboratory conditions, a sterile artificial medium with sugar and other nutrients is required. Through research, an excellent medium for growing seeds without fungi was developed. Inside the bottle where orchid seedling is grown is a miniature glasshouse which protect seedlings from unfavorable environmental conditions. Using artificial media has insured the growing of nearly all orchid seeds into mature plants.
- 1. Flasking and reflasking or protocorms – when orchid seed or embryo is planted in a culture bottle, numerous seedlings germinate in a very limited space with little available food. The first sign of successful germination is when orchid seed starts to swell and turns green. As growth continues, the embryo becomes bigger and assumes a flattened top shape called protocorm. A small amount of seed sown produce hundreds of tiny photocorms growing in limited space. At this stage, transplant them into fresh medium and table for further development and rapid growth.
- 2. Composting and Repotting Seedlings – Orchid seedlings are ready to be transplanted from culture bottles when roots and leaves are fully developed. Dendrobiums may be potted after 4 to 6 months. Vandas, Phalaenopsis and Cattleyas in 6 to 8 months after reflasking before seedlings are ready for community pots. Seedlings should be potted only in sterile potting medium and pots to avoid damping-off.
Potting medium may consists of sterilized fine Osmunda fibers, charcoal, chopped tree fern (paslak).
After removing seedlings from bottles, wash out all agar from seedlings and wash them in fungicide suspension. Drain excess moisture and sort out seedlings according to size. Small seedlings are planted in community pots, while the bigger ones are potted individually in small pots.
Like most plants, orchids must attain a certain degree of vegetative growth before they are capable of flowering. This is referred to as the stage of ripeness to flower.
For Phalaenopsis, the minimum number of leaves is 3 before they will flower, 8 in Vandas, and 14 in Aranda. Vegetative growth of seedlings can be accelerated to attain the stage of ripeness to flower. Optimum growing conditions such as high temperature, humidity, adequate and continuous light, frequent application of dilute fertlizer have shown hastening of flowering in Vanda and Phalaenopsis.
Factor affecting flower bud initiation
Photoperiodism – is the development of plants as conditioned by the length or duration of light. There are 3 orchid categories based on their response to photoperiod: 1) short-day; 2) day-neutral; and 3) long-day groups.
Temperature – for some orchids, low temperature is required to induce flowering. Temperature interacts with photoperiod as regards to flower induction. Some orchids required low temperature to induce flowering, as follows: Cymbidium, Cattleya Mossiae; Dendrobium, Phaphiopedium, Phalaenopsis, Schilleriana.
Orchids flowers do not mature until 3 to 4 days after they open. It is important to know how old the blooms are before harvesting. Flowers cut before they mature will not hold up nor last as longer as the matured flowers. Spray-type orchid present no problem. Each floret opens 1 ½ to 2 days apart. If 3 or more flowers are open on the spike, the lower flower is mature and can be separated.