The biggest problem with growing orchid cacti is figuring out just what they are.
They are cacti, but are not spiny. Their spectacular blossoms are neither orchids nor orchid-like.
Sometimes orchid cacti are called epiphyllums, which is also the botanical name of some (but not all) orchid cacti. The word epiphyllum means "on the leaf" and refers to the way the flowers pop out from the edges of the ... well, they look like leaves but they're really just flattened stems.
Enough with the semantics. The important thing is that fat flower buds on my orchid cacti's stems are about to burst open into spectacular white, pink or scarlet blossoms. And coaxing forth these blossoms required very little effort on my part.
This cactus likes moisture
Although orchid cacti, or epies (short for epiphyllums) as they are sometimes called, are true cacti, they are not native to deserts but to lush, tropical jungles. There, they nestle into forks in tree branches or into rock crevices where enough humus has accumulated to retain moisture. The plants enjoy soils that are both well-drained and retain moisture. I use my standard potting mix with a little extra perlite for drainage; you could also make up a mix using peat moss, compost, and perlite or sand.
Here, out of the jungle, the plants look right at home in hanging baskets, from which their arching, flattened stems, scalloped along the edges, can swoop up and out as fountains of greenery.
In contrast to the night-blooming cereus cactus, an epiphyllum species that is spectacular and fragrant the few nights that it blossoms, the flattened, green stems of orchid cactus are nice to look at year round.
On some of my plants, the stems are so thin they droop languidly over the edge of the pots from their own weight. My white-flowered epi, in contrast, has sturdy stems that reach out a couple of feet in all directions before succumbing to gravity.
Give them a rest
In return for flowers, which last for weeks but usually appear only once a year, my epies ask for regular watering, occasional fertilizer and, once a year, a rest. The one period when epies should not be watered is, conveniently, beginning in fall when they begin their annual rest. It's always iffy watering a hanging basket indoors, when a little too much water means scurrying for a bowl to catch the dripping.
To set flower buds, the plants also allegedly need to experience the naturally long nights of autumn and winter, so they mustn't be interrupted by artificial light after dark. I used to put my plants in a bright window in a cool corner of my basement and forget about them until ready to bring them upstairs and let water and warmth bring on the flowers. I've since found that merely not watering them at all from the time they are brought indoors in autumn is sufficient to induce flower buds. Swelling flower buds indicate that it's time to start watering again.
In summer, the plants like being outdoors in filtered shade such as they might enjoy in their native haunts.
What's in a name?
So what are my plants, really? I still don't know. Epiphyllums and related species were first hybridized in England about 1830. At first, the only colors available were whites, pinks and reds, not much of a limitation given the drama of the blossoms. Humans will be humans though, and in 1950, breeding efforts brought forth the first yellow orchid cactus, called Reward. The original cuttings sold for $400. Perhaps blue epies are on the horizon.
The point is that epies have been so hybridized that many now have few or no epiphyllum genes in them. No matter: All the epies are easy to care for, attractive year round and stunningly beautiful in bloom.