Selenicereus costaricensis
| Light | Bright light with some direct sun; tolerates partial shade |
|---|---|
| Water | Regular in the growing season; let the top of the mix dry between waterings, drier in winter |
| Soil | Rich but free-draining mix with plenty of organic matter (see Soil and potting mix) |
| Temperature | Warm; protect below about 10 °C, no frost (roughly USDA zones 10–11) |
| Propagation | Cuttings (easy) and seed; grafting sometimes used |
| Toxicity | Non-toxic; the fruit is edible |
Selenicereus costaricensis is a vigorous climbing and sprawling cactus grown above all for its striking red-fleshed dragon fruit. A member of the Selenicereus genus (and long known under the name Hylocereus costaricensis), it produces large night-opening flowers followed by pink-skinned fruit whose deep magenta flesh makes it a favourite of fruit growers and cactus collectors alike.
Description
Selenicereus costaricensis is a scrambling, epiphytic-to-lithophytic cactus that climbs by aerial roots, throwing out long, fleshy, three-angled (triangular) green stems that branch freely and can cover a considerable area given support. The ribs are scalloped along their edges, each notch bearing a small areole with a few short spines. Like other dragon-fruit species, it clings to trees, rocks and walls, sending down anchoring roots wherever the stems touch a surface.
The flowers are large, showy and nocturnal, opening for a single night with white inner petals surrounded by greenish or yellowish outer segments. Successful pollination is followed by the familiar dragon fruit: a rounded berry with soft, leafy scales over pink-red skin, and — the species' signature trait — vividly red to purple flesh dotted with tiny black seeds. The intense pigment comes from betalains and readily stains hands and worktops.
Distribution and habitat
The species is native to Central America, associated in particular with Costa Rica and neighbouring countries, where it grows in warm, seasonally dry to humid tropical settings. It behaves as a climbing epiphyte or rock-dweller, scrambling over host trees and rocky outcrops rather than rooting in deep soil. It is now cultivated well beyond its native range across the tropics and subtropics as one of the red-fleshed dragon-fruit crops.
The taxonomy of the dragon-fruit cacti has been much revised; plants formerly placed in Hylocereus are now generally treated within Selenicereus, which is why this species is widely traded under both names.
Cultivation
Selenicereus costaricensis is easy-going and fast-growing where it is kept warm. Unlike most desert cacti it appreciates richer conditions: give it a free-draining but organic-rich mix, bright light with some direct sun, and steady warmth. Because the stems are heavy and love to climb, provide a stout post, trellis or frame for support; many growers train the plant up a sturdy stake with a bushy head on top.
Water regularly through the warm growing season, letting the surface of the mix dry between waterings, and ease off in cooler weather. Feeding during active growth encourages the strong stems needed to carry fruit. Protect the plant from cold — it resents temperatures near freezing and is best kept above about 10 °C — and from the harshest full-day sun in very hot climates, which can scorch the stems. See Watering and Repotting for general technique.
To set fruit, plants must first be mature and produce their night flowers. Many dragon-fruit clones are partially or fully self-incompatible, so hand-pollination — moving pollen between flowers with a small brush on the night they open — often greatly improves fruit set. Growing more than one clone nearby helps.
Propagation
Propagation is easiest from stem cuttings: a length of mature stem, allowed to callus for several days before potting into a gritty, barely moist mix, roots readily in warmth and reaches flowering size far sooner than a seedling. This is the standard way to reproduce a named fruiting clone true to type.
Seed from ripe fruit also germinates easily on a warm, humid surface, but seedlings are variable and slow to reach fruiting size, so seed is used mainly for breeding rather than for reproducing a particular selection. Grafting is occasionally practised as well, but it offers little advantage over cuttings, which already root and grow quickly. See Propagation — seed and Propagation — cuttings for full walkthroughs.
Common problems
- Rot — the commonest cause of loss, from a waterlogged mix, cold-and-wet conditions, or damaged tissue; stems go soft, yellow and mushy.
- No fruit despite flowers — usually a pollination issue with a self-incompatible clone; hand-pollinate and grow a second clone nearby.
- Etiolation and weak stems — too little light produces thin, pale growth that cannot support fruit.
- Pests — mealybugs (white fluff in the areoles) and scale are the usual culprits; see Pests and diseases.
See also
- Selenicereus — the genus overview
- Grafting · Soil and potting mix · Watering · Repotting
- Propagation — cuttings · Propagation — seed · Pests and diseases