Though it is mostly true that any small cactus can be grown in hanging baskets, some are better suited to these containers than others. The ones with arching, pendant, or trailing stems are the best of all for hanging baskets.
Bristle tufted twig cactus (Erythrorhipsalis pilocarpa)
Native to Brazil, this is one of the epiphytic cacti. When young, the stems are more upright. But, as the plant matures the stems become rather drooping. This has greenish-purple stems that are grooved and cylinder-shaped. These are produced in whorls. The stems are covered with whitish bristle-like spines, which explains the common name. Its blossoms are white. Later, these produce fruits that ripen to deep red.
Cleisto (Cleistocactus winteri)
While most of its relatives tend to be more upright, this particular species has stems that have a pendant or trailing habit. The individual stems can reach four or so feet in length. This plant is noted for the colorful yellow spines that literally cover the surface of the stems. It features vivid orange blossoms that can last for several days.
German empress (Nopalxochia phyllanthoides
Some sources may still list this as being a species of orchid cactus. A native of Mexico, this ephiphyte has become a favorite house plant. The trailing stems are toothed. While the young stems are rounded, they flatten with age and assume a trailing habit. The lovely pink to red flowers have pale tips. Most of the time, this blooms during the spring and summer.
Mistletoe cactus (Rhipsalis spp.)
This is also known as wickerwork cactus. Native to the tropics of both the New World and elsewhere, this is sometimes called willow cactus. These plants feature branches that tend to develop in whorls. The thin, pencil-shaped, pendant stems grow together to form joints. In the wild, they occur as epiphytes on trees. These stems are spineless. The small, whitish flowers eventually produce sticky, berry-like fruits that ripen to various colors, such as purple, red, and white.
There are a number of species that are commonly grown.
Orchid cactus (Epiphyllum spp.)
Numerous species and cultivars of the orchid cacti are available. Some of these are night blooming.
The orchid cacti are best known for their remarkable blossoms. Native to the tropical regions, these feature rather flat stems that are mostly smooth and spineless. Because the stems often assume a pendant habit, these are excellent for hanging baskets.
The large, vivid blossoms open on stems that are usually a year or so old. This usually occurs during the spring and summer months. These glistening blossoms range in color from purple and cerise to red with shades of delicate pink and pastel yellow. Opening in clusters, these can be three to nine inches across.
Rat-tail cactus (Aporocactus flagelliformis)
This is an excellent choice for novice gardens. Native to Mexico, this species is often grown as a house plant. It has cylindrical, slender stems, less than two inches thick. These are either trailing or creeping. They can reach up to three feet or so in length. Decorated with ribs, these stems are covered with brown or yellow spines. Blooming mostly during the spring, this species features lovely red blossoms, which eventually produce small red fruits.