Stenocereus dumortieri
| Light | Full sun to bright light; acclimatise gradually to avoid scorch |
|---|---|
| Water | Moderate in the growing season; keep dry and rested in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11 |
| Propagation | Cuttings (easy) and seed |
| Toxicity | Non-toxic to cats and dogs |
Stenocereus dumortieri is a tall, tree-like columnar cactus from central and southern Mexico that forms dense, candelabra-like stands of blue-green stems. In habitat it grows several metres — sometimes to about 15 m — high, developing a well-defined woody trunk from which numerous erect branches rise in a candelabra pattern to build its distinctive silhouette. It is sometimes separated into its own genus as Isolatocereus dumortieri, a name still widely seen in the trade and older literature. It belongs to the genus Stenocereus.
Description
Stenocereus dumortieri produces slender, erect columns that are typically blue-green to grey-green, glaucous with a greyish wax, and carried on several low, triangular ribs (usually about six). The stems arise from a stout, well-defined trunk and branch repeatedly above it, so that a mature plant carries many parallel erect columns in a candelabra — the source of its distinctive appearance. Areoles along the rib margins bear short radial spines with a few longer centrals, modest compared with those of many of its relatives, so the overall effect is more architectural than fiercely armed.
Flowers are borne toward the stem tips and are comparatively small for a columnar cactus, white to pale green and tubular to funnel-shaped; they open at night and last into the following morning. As with many columnar species, flowering is favoured by good light and a settled, mature plant. The fruits are small and fleshy, reddish within and not spiny.
Distribution and habitat
The species is native to central and southern Mexico, where it grows in arid and semi-arid scrub, on rocky slopes and in valleys, often as a conspicuous element of the vegetation. In these settings it forms large, colony-like stands that can dominate the skyline of a hillside. It is adapted to seasonal rainfall with a pronounced dry period, drawing on its water-storing columns to ride out drought.
Cultivation
Stenocereus dumortieri is a robust, undemanding grower given warmth, sun and sharp drainage. Plant it in a very free-draining, mostly mineral mix and give it as much light as you can — full sun once acclimatised — to keep the columns compact and well-coloured; plants grown too dark tend to etiolate and lean. Water moderately through the warm growing season, always letting the mix dry out between soakings, and keep the plant dry and cool over winter to prevent rot and harden it against cold.
It is fast and vigorous for a columnar cactus and can put on considerable height in a pot before eventually wanting more room; see Repotting for technique and timing. In cold climates it is best kept as a container plant that can be moved under cover before frost. General guidance on frequency and seasonality is in Watering.
Propagation
Because the plant branches so freely, stem cuttings are the quickest and most reliable route: remove a branch, let the cut surface callus for a week or more in a dry, shaded spot, then set it in a gritty, barely-moist mix until roots form. The species can also be raised from seed, which germinates readily with warmth and humidity but takes considerably longer to reach any size.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a slow-draining mix or cold, damp winter conditions; stems soften and discolour, often from the base.
- Etiolation — too little light produces thin, pale, stretched growth that never firms up into proper columns.
- Cold damage — frost scorches and scars the stems; protect from freezing temperatures.
- Pests — mealybugs (white fluff in the areoles) and, under glass, red spider mites are the most common nuisances. See Pests and diseases.
See also
- Stenocereus — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Propagation — seed · Repotting