Orchid cactuses are unusual cactuses that have a spectacular bloom. They are often grafted onto other cactus stock to produce flowers. The family name is Epiphyllum and numerous species are collected by cactus lovers. The plant's name is derived from the Greek "epi," meaning on or upon, and "phyllum," meaning leaf. Early botanists thought the flower sprang from a leaf. Actually the plant has no leaves--what appear to be leaves are actually stems. They are easy to care for indoor plants that are not susceptible to many diseases or insects.
Orchid cactuses are actually not related to orchids. They are native to tropical forests and are found wild in Mexico and Central America. Some species can be found in North and South America and even the Caribbean. In native habitat, the plants hang from trees, just like orchids do. This habit is called epiphytic and occurs when a plant roots in the moss and leaf litter of a tree crotch or branch angle. The organic root medium in the tree and bird and animal waste provide all the fertilizer an Epiphyllum needs in the wild.
Epiphyllum are characterized by a flat leaflike stem that is spineless. The plants have a hanging or sprawling habit with fragrant flowers at the ends of the stems. The flowers open at night, which has also given them the name queen of the night. These are white with yellow or pink sepals and last a very short time. In their place a fruit grows that is edible and juicy, but filled with black seeds.
Orchid cactus are propagated by cuttings. When the flower dies, the stem should be cut off to redirect energy to producing more stems and flowers. The cut stem can now be used as a cutting. Regular potting mix with a little sand is appropriate for the cuttings and they can be dusted with a rooting hormone or allowed to root themselves. All they need is time and consistent moisture. Fertilizing is not needed until the plants achieve true stems, not the rounded stems they begin with.
Commercial liquid fertilizers work well. A fertilizer in the range of a 5-1-4 is a good choice. They need quite a bit of nitrogen (the first number) since the wild plant would be exposed to a lot of rotting organic matter. If you want to promote blooms, move to a low-nitrogen fertilizer. This will signal the plant that it needs to reproduce itself and it will send out flowers. If your cactus has attained the size you want and you just want a maintenance fertilizer, a balanced one that is diluted by half with water will complement its care.
How to Fertilize
Fertilizing does not need to take place when the plant is not actively growing. Winter is the orchid cactus's dormant period, so no fertilizer is needed. The rest of the time, fertilizing should take place when you water. Dissolving a diluted amount of liquid fertilizer and watering in until the plant leeches moisture will support the growth and development of flowers. The leeched water should be dumped from the saucer so the roots do no stay over-wet.