Propagation refers to creating a new orchid plant from a mother plant. While many common orchids are multiplied by dividing the root ball, vegetative propagation involves taking a physical piece, or cutting, from the original plant to grow a clone. This method allows growers to increase their collection of specific, desirable varieties without the lengthy process of seed germination. Success relies heavily on selecting the correct plant material and providing the necessary environmental conditions for new growth to emerge.
Identifying Orchids Suitable for Cutting Propagation
The feasibility of using a cutting depends on the orchid’s growth habit, classified as either monopodial or sympodial.
Monopodial orchids, such as Phalaenopsis (Moth Orchids) and Vanda, grow vertically from a single, central stem. Propagation is achieved by excising a plantlet, known as a keiki, that develops on the flower spike or at the plant’s base. Keikis are genetic clones and are ready for removal once they have developed several leaves and three or more roots at least two to three inches long.
Sympodial orchids, like those in the Dendrobium genus, grow horizontally and produce pseudobulbs that store water and nutrients. While many sympodial types are propagated by division, Dendrobium species are often propagated through cane cuttings. This method utilizes mature, sometimes leafless, canes (pseudobulbs) that are no longer flowering. Selecting a healthy, plump cane ensures the cutting has sufficient energy reserves to initiate new growth before establishing a new root system.
Preparing and Taking the Cutting
Precision and hygiene are paramount when preparing orchid cuttings to prevent pathogens that cause rot. All cutting tools, such as a razor blade or pruning shears, must be sterilized with rubbing alcohol or a bleach solution before and after each use.
Dendrobium Cane Cuttings
For Dendrobium cane propagation, a healthy cane is cut into sections. Each piece should contain two to four nodes, which are the points where new growth will emerge. These sections are typically a few inches long, and the cuts must be made cleanly between the nodes.
Keiki Removal
When removing a keiki from a Phalaenopsis flower spike, the cut is made on the spike itself, leaving one to two inches of spike tissue attached above and below the keiki. Once separated, the open wounds on both the cutting and the mother plant must be treated immediately. Dusting the cut surface with a natural fungicide, such as cinnamon powder, seals the wound and prevents fungal entry. The cutting should then be allowed to dry and callus for several hours or overnight before being placed in the rooting medium.
Post-Cut Care and Rooting Methods
The environment provided to the cutting determines successful rooting and establishment. Orchid cuttings require a rooting medium that is loose, highly aerated, and retains consistent moisture without becoming waterlogged. Sphagnum moss is a frequently used choice due to its excellent water retention and sterile properties, often used alone or mixed with fine bark pieces. The cutting is laid horizontally on top of the moist moss, ensuring the nodes are in contact with the medium, or a keiki is potted so its base rests just above the mix surface.
High humidity and warmth stimulate root formation. Creating a humid microclimate by placing the pot inside a clear plastic bag or under a humidity dome is often necessary, but this enclosure must be vented periodically for air exchange. The ideal temperature range for rooting is between 65 and 80 degrees Fahrenheit, provided with bright, indirect light.
The medium should be kept lightly moist, not soggy. New growth may take several weeks or months to appear. Once the cutting has established substantial roots, it can be transitioned to a small, permanent pot and a less humid environment.