Stenocereus griseus
| Light | Full sun to bright light; tolerates intense heat |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, mostly dry in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; happiest in warm, frost-free conditions (USDA zones 9b–11) |
| Propagation | Cuttings (readily) and seed |
| Toxicity | Non-toxic to cats and dogs |
Stenocereus griseus is a tall, tree-like columnar cactus native to the seasonally dry tropics of Mexico, northern South America and the southern Caribbean, where it has long been grown for its sweet edible fruit and planted in rows to form living fences. Its bluish-grey to greyish-green stems branch from a short trunk into a candelabra of ribbed columns, and it is widely valued as a source of pitaya — the juicy fruit that gives the plant its common names dagger cactus and pitayo de mayo. It is one of the more economically important members of the genus Stenocereus.
Description
Stenocereus griseus is a large, branching cactus that in habitat becomes tree-like, often reaching several metres tall with a distinct short trunk from which numerous erect stems arise in a candelabra habit. The stems are stout and cylindrical, typically grey-green to bluish-grey — the colour that gives the species its name (griseus meaning "grey") — and divided into a modest number of prominent ribs.
Along the ribs sit felted areoles bearing stiff spines: a few longer central spines surrounded by shorter radials, variable in length and colour from grey to brownish. Funnel-shaped white flowers, opening at night, appear along the upper stems. They are followed by rounded, spiny fruits — the pitayas — with sweet red to purplish pulp studded with small seeds.
Distribution and habitat
The species occurs in the dry tropics of Mexico (notably Oaxaca and Veracruz), northern South America — particularly Colombia and Venezuela — and nearby islands of the southern Caribbean such as Aruba, Bonaire and Curaçao. It grows in hot, arid and semi-arid lowlands — thornscrub, dry forest and coastal scrub — on rocky or sandy ground, often as a conspicuous element of the landscape.
Across this range it has a long history of human use, and stands of the cactus near settlements are frequently the descendants of plants set out as hedges or for their fruit, blurring the line between wild and cultivated populations.
Cultivation
Stenocereus griseus is a vigorous, heat-loving plant that is straightforward to grow given warmth and sun. Provide a very free-draining, mostly mineral mix and a position in full sun; the species relishes strong light and high temperatures. Water thoroughly during the warm growing season once the soil has dried, then reduce sharply and keep the plant mostly dry through the cooler months. See Watering for general technique.
Like most columnar cacti it resents cold, wet conditions and has little frost tolerance, so in temperate climates it is best grown under cover or moved somewhere bright and frost-free for winter. Given room it can grow quite large, so account for its eventual size and repot into a stable, heavy pot as needed (see Repotting). In frost-free regions it is planted directly in the ground as a hedge or fruit crop.
Propagation
The species propagates very readily from stem cuttings, which is the traditional method for establishing living fences: sections of stem are cut, allowed to callus, and set to root directly. This ease of vegetative propagation makes it simple to bulk up plants and to preserve particular fruiting forms. It can also be raised from seed sown on a warm, gritty surface. See Propagation — cuttings and Propagation — seed for full walkthroughs.
Common problems
- Rot — the usual result of cold, wet conditions or a slow-draining mix; stems soften and discolour, often from the base.
- Etiolation — too little light produces thin, pale, weakly-ribbed growth instead of the stout grey columns.
- Pests — mealybugs (white fluff in the areoles) and scale are the most common; watch also for spider mites in hot, dry indoor conditions. See Pests and diseases.
See also
- Stenocereus — the genus overview
- Propagation — cuttings · Propagation — seed · Soil and potting mix · Watering · Repotting · Pests and diseases