Disocactus flagelliformis
| Light | Bright, indirect light; some direct morning sun. Tolerates more light than most epiphytes |
|---|---|
| Water | Regular through the growing season; keep barely moist, never waterlogged. Reduce in winter |
| Soil | Open, humus-rich yet free-draining mix (see Soil and potting mix) |
| Temperature | Keep above about 7–10 °C; a cool, dryish winter rest aids flowering. USDA zones 10–11 |
| Propagation | Cuttings (easy); also seed |
| Toxicity | Non-toxic to cats and dogs |
Disocactus flagelliformis, the rat-tail cactus, is a trailing epiphytic cactus with long, slender, ribbed pendant stems and vivid pink to magenta flowers. Its cascading habit and free-flowering nature have made it a classic hanging-basket cactus, grown as a houseplant for well over a century. It belongs to the epiphytic genus Disocactus and was long known under its older name Aporocactus flagelliformis.
Description
Disocactus flagelliformis produces many thin, rope-like stems that arch out and then hang, often reaching a metre or more in length in an established plant. Each stem is only around 1–2 cm thick, cylindrical and softly ribbed, clothed in short, fine, bristle-like spines that are more decorative than fierce. Young stems grow upright before their weight pulls them into the characteristic trailing "rat tail" shape that gives the plant its common name.
In spring the stems flower generously along their length. The blooms are showy and slightly irregular (zygomorphic), tubular at the base and up to about 8 cm long in bright shades of pink, cerise or magenta. Each flower lasts several days, and a mature basket in full bloom is a striking sight.
Distribution and habitat
The species is native to central Mexico, where it grows as an epiphyte in oak and pine woodland, rooting among moss and leaf litter on tree branches and occasionally on rocks. In these habitats it enjoys dappled light, good air movement and rain during the growing season followed by a drier, cooler period. Long cultivation and naturalisation have blurred the exact wild range, and truly wild populations are now uncommon.
Like all cacti, Disocactus flagelliformis is listed under CITES Appendix II, but nursery-propagated plants are inexpensive and freely traded.
Cultivation
This is one of the easiest and most rewarding trailing cacti, ideal for a hanging basket or a pot on a shelf where the stems can spill freely. Grow it in an open, humus-rich but free-draining mix — a cactus mix enriched with a little extra organic matter suits it well, reflecting its epiphytic origins. Give it bright light with some gentle direct sun; it tolerates more light than most jungle cacti and flowers best when not too shaded.
Unlike desert cacti, the rat-tail appreciates more regular water through spring and summer, staying lightly moist but never soggy. Through winter, cut back watering and keep the plant cooler and drier — this rest period is key to a strong flush of spring flowers. Feed with a dilute balanced fertiliser during active growth. The stems are brittle where they join, so handle and repot with care. Because of its cascading habit it is often grown grafted onto an upright columnar rootstock as a "standard", though it thrives equally well on its own roots.
Propagation
Propagation is very easy from stem cuttings. Remove a length of stem, let the cut end callus for a day or two, then lay or insert it in a gritty, barely moist mix; roots form readily in warm conditions. Whole trailing stems will often root along their length where they touch soil. The species can also be raised from seed, and is a common rootstock and parent in grafted and hybrid work.
Cultivars
D. flagelliformis has been crossed with related epiphytes to produce a range of hybrids with larger or differently coloured flowers, historically grouped under names such as ×Aporophyllum (crosses with Epiphyllum-type plants). These retain the easy trailing habit while offering blooms in reds, oranges, purples and bicolours. See the Disocactus genus page for more on the epiphytic cacti and their hybrids.
Common problems
- Rot — the commonest cause of loss, from a mix that stays wet or from overwatering in cold weather; stems soften, discolour and shrivel from the base.
- Shy flowering — usually too little light or the lack of a cool, dry winter rest; both are needed to trigger the spring display.
- Broken stems — the slender stems snap easily at the joints; site the plant where the trails will not be knocked, and support new growth until it hangs naturally.
- Pests — mealybugs (white fluff in the crevices) and red spider mites (fine webbing, dull bronzed stems) are the usual offenders; see Pests and diseases.
See also
- Disocactus — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Repotting