Hylocereus undatus
| Light | Bright light with some direct sun; tolerates part shade, but flowers and fruits best in strong light |
|---|---|
| Water | Regular through the warm growing season, letting the top of the mix dry between waterings; much drier and cooler in winter |
| Soil | Rich but free-draining mix; more organic matter than most desert cacti tolerate (see Soil and potting mix) |
| Temperature | Frost-tender; happiest in USDA zones 10–11, protect below about 5 °C |
| Propagation | Cuttings (fast and reliable); also seed |
| Toxicity | Non-toxic to cats and dogs; the fruit is edible |
Hylocereus undatus is the widely grown white-fleshed dragon fruit, a vigorous climbing and scrambling cactus grown across the tropics for its large white night-blooming flowers and its striking pink-skinned, green-scaled fruit. A member of the genus Hylocereus, it is an epiphytic and lithophytic species that clings to trees and rocks with aerial roots, and it is by far the most commonly cultivated of the pitaya-producing cacti.
Description
Hylocereus undatus is a sprawling, three-angled climbing cactus with fleshy green stems that can grow many metres long. The stems are triangular in cross-section, with wavy, horny margins bearing small areoles and short, insignificant spines. Along the length of each stem the plant produces abundant aerial roots, which anchor it to bark, walls and rock and also draw up moisture, letting it climb and scramble over its supports rather than stand on its own.
The flowers are spectacular: very large, funnel-shaped and pure white, often 25–30 cm long, opening for a single night and usually fading by morning. Like many night-blooming cacti they are heavily fragrant and rely on nocturnal pollinators. Successful pollination gives the familiar dragon fruit — an oblong berry with bright pink to red skin adorned with green-tipped fleshy scales (the "wings"), enclosing sweet, mild white flesh flecked with tiny edible black seeds.
Distribution and habitat
The exact wild origin of H. undatus is uncertain, as it has been cultivated and spread by people for so long, but it is generally regarded as native to Central America and southern Mexico. It now grows throughout the tropics and subtropics, both in commercial orchards and as a naturalised escape, thriving in warm, frost-free climates.
In the wild and in cultivation it behaves as an epiphyte and lithophyte, rooting in leaf litter, on tree trunks and among rocks rather than in deep soil. It favours warmth, humidity and bright but often dappled light, using surrounding trees both for support and for a little shade from the fiercest midday sun.
Cultivation
Compared with most desert cacti, Hylocereus undatus is thirsty and hungry, reflecting its tropical, semi-epiphytic roots. Grow it in a rich but still free-draining mix with plenty of organic matter, and water regularly through the warm months, letting only the surface dry between waterings; ease right back in winter and keep it on the dry, cool side to avoid rot. It is decidedly frost-tender, so in cooler climates it is grown under glass or brought in for winter.
Because the stems are long and floppy, the plant needs support — a sturdy post, trellis or wall it can climb, gripping with its aerial roots. Strong light encourages flowering, but young plants and those in very hot regions appreciate a little afternoon shade. Feed during active growth, and be patient: given warmth, light and a support to scramble up, established plants can flower and set fruit freely. See Watering, Repotting and Pests and diseases for general technique.
Propagation
Cuttings are the easy and popular method, and the usual way to reproduce named fruiting selections. A length of mature stem is cut, allowed to callus for a few days, then set in a free-draining mix to root; cuttings establish quickly and reach flowering size far sooner than seedlings. Seed is also viable — the fruit is full of tiny seeds that germinate readily on a warm, humid surface — but seedlings are slower and will not come true to a particular fruiting clone. See Propagation — cuttings and Propagation — seed for full walkthroughs.
Note that many dragon fruit varieties are partly or wholly self-incompatible, so growers aiming for fruit often keep more than one clone and may hand-pollinate the night-opening flowers to ensure a good set.
Common problems
- Rot — the most frequent cause of loss, usually from cold, wet, poorly drained conditions; stems soften, discolour and collapse.
- No flowers or fruit — commonly from too little light, plants that are still juvenile, or lack of a compatible pollen partner for self-incompatible varieties.
- Cold damage — even a light frost scars or kills the tender stems; protect from cold well before freezing.
- Pests — mealybugs, scale and, under dry indoor conditions, spider mites can all trouble the stems; ants and slugs may be drawn to flowers and ripening fruit.
See also
- Hylocereus — the genus overview
- Propagation — cuttings · Propagation — seed · Soil and potting mix · Watering · Repotting · Pests and diseases