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 85 degrees, and humidity of 50 percent 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.