Like most plants, orchids are able to reproduce themselves in two different ways; the one way sexually by seed, and the other asexually by vegetative propagation. For the beginner, vegetative propagation is commonly used to build up one's orchid collection. Vegetative propagation can be accomplished in three ways; that is, by division, back bulbs and offshoots. The technique of each differs primarily in the means of producing the new individual and in the early care.
Although large, overgrown orchids can be challenging to divide, spending a few minutes examining the plant before cutting can go a long way toward making the job easier and assuring strong divisions that will produce vigorous growth quickly.
DIVISION
After a mature orchid plant has grown and flowered for several years the beginner finds the plant is too large for the size pot in which it is growing, and he faces two choices. He can either repot the plant into a larger container, or he can divide the plant into two or more separate individuals. If the plant has but one lead (that is, a new growth) it can be divided by cutting the plant into groups of three or four pseudobulbs. The front group with the lead pseudobulb would be known as a "division." The other group or groups of pseudobulbs without any active lead would be termed back bulbs. If a plant has several leads it can be divided in such a way that there will be one or more divisions and one or more back bulbs. In other words, a division is a group of pseudobulbs which contains an active lead or new growth after the plant is broken up; whereas, the back bulbs are a group of old pseudobulbs that have no active lead, but on which there are one or more dormant "eyes" which may be forced into active growth.The illustration in Figure A shows the arrangement of the rhizomes and pseudo-bulbs of a Cattleya plant with but a single lead. Such a plant may be divided by cutting through the rhizomes or root stock at the point indicated by the letter x. This will produce one division and two back bulbs as indicated. In Figure B a Cattleya plant with several leads is cut as indicated, producing three divisions and several back bulbs. The actual cutting of the rhizome is commonly done after the plant has flowered, but previous to repotting. Usually a V-shaped notch is cut more than half way through the rhizome. The plant then is not disturbed until the dormant "eyes" on the back bulbs begin to break. As soon as the new growths are started the plant can be taken from its pot, broken up and repotted. After the division has been repotted, the plant should be carefully sprayed but not watered until root growth has become quite evident. Plants may then be given more water and treated as established plants.
Backbulbs can be placed in a clay pot with a pad of sphagnum moss in the bottom. Spray with water daily to keep plant and moss hydrated.
BACKBULBS
Backbulbs, if obtained in the way outlined above, may have an active growth beginning, in which case they can be repotted and treated similarly to a division; however, if they do not possess an active "eye" they may be potted in a small pot, two and one-half to three inches in size, making sure that the "eyes" are above the potting media. The potted back bulbs can then be placed in the poorest growing corner of the greenhouse. The bulbs and leaves should be sprayed frequently, but the pot should not be soaked. In some cases, "eyes" will begin to break within a few weeks. In other cases, they may remain dormant for two years, suddenly bursting into activity. As long as the leaf and bulb are green there is hope for their eventual development. Another way of handling back bulbs is to fill six-inch pots with sphagnum moss and place the back bulbs on the live moss. Keep the plants in a fairly humid atmos-sphere and the "eyes" will soon develop. Still another way to save the back bulbs is to take a wooden flat or tray and line it with a layer of sphagnummoss, stack the back bulbs in the flat and keep them in a warm, moist section of the greenhouse. Spray the bulbs and leaves every day or so and watch the back bulbs carefully. As soon as one gets under way it should be potted. Any bulbs found developing wet rot should be removed at once and destroyed.
OFFSHOOTS
Some types of orchids, such as Dendrobiums, will develop offshoots along the stem. They appear to be, and are, small but individual plants. These may be allowed to grow to maturity and then carefully cut from the parent plant. The young offshoot, or "keiki" as it is often called, can be potted up similarly to a back bulb. See our Video Library for demonstrations on removing a keiki and potting a keiki as well as an explanation of keikis and air roots.
