Phalaenopsis orchids produce all their leaves at the base of the plant. This makes taking cuttings of stems with leaf nodes on them for propagation impractical. However, as the orchid matures, the new leaves emerge higher and higher on the stem. The lower leaves turn yellow and drop. The area they used to occupy starts putting out roots, leaving a long area under the plant with essentially a fat stem with roots emerging from it -- a useful area for propagation.
Cut off the top of the phalaenopsis orchid just below highest roots using a sharp, disinfected knife. Take care not to bruise or mangle the plant as you cut. Dull knives damage plant tissues and make the task more difficult.
Plant the top portion in a separate pot, allowing the roots to touch the orchid growing media. Leave the stub in its container, in the same growing conditions used for the parent orchid: bright diffused light and ample humidity. The Texas Cooperative Extension recommends 1,000 to 1,500 foot candles of light, temperatures well above 60 but below 29.4 degrees C, and humidity of 50 per cent or higher.
Wait one to four weeks for small clones of the parent plant to begin forming on the stub. These are called keikis, or baby orchids.
Cut the keikis away from the stub once they have three roots. Use a sharp, disinfected knife once again, and ensure that the small roots are not harmed during the removal process. Handle the keikis gently to avoid tissue damage.
Re-pot each keiki separately in seeding media or orchid potting media. Keep them in bright, diffused light with abundant ambient humidity, and ensure that the roots are moist but never sitting in soggy soil or standing water.
Leave one or more keiki on the parent stub for quicker flowering. Keikis left on the stub tend to flower sooner than those that are transplanted.
If the keikis' roots begin to turn green on the outside, water less often. Allow them to dry to a white colour before watering again. Compost tea makes a nutritious fertiliser, rich in micronutrients and macronutrients, but gentle enough to use on keikis to help them establish, grow and sometimes even resist fungal diseases.