Light
Bright Indirect Light
Bright indirect light or partial shade. Protect from scorching afternoon sun.
Reference image 
Reference image Acanthocereus tepalcatepecanus
Tepalcatepec Night-blooming Cereus
Overview
Acanthocereus tepalcatepecanus is a scrambling, semi-shrubby succulent cactus native to seasonally dry tropical ecosystems. Known for its slender, arching stems and large nocturnal blooms, this species is highly sought after by succulent collectors for its unique wild form and beautiful adaptation to dry forest understories 1.
Taxonomy and Naming
The species is classified within the genus Acanthocereus of the Cactaceae family. Its specific epithet "tepalcatepecanus" refers to its type locality in the Tepalcatepec Basin of Mexico. It was previously classified under the genus Peniocereus as Peniocereus tepalcatepecanus before modern molecular studies reinstated it in Acanthocereus 2.
Distribution and Habitat
This species is endemic to southwestern Mexico, spanning states such as Michoacán, Jalisco, Guerrero, and Oaxaca. It thrives in deciduous tropical dry forests at elevations between 200 and 800 meters, typically growing under the light shade of larger shrubs and trees on rocky or gravelly soils 1.
Appearance
It features cylindrical to slightly ribbed, grayish-green stems that can sprawl or climb up to 1-2 meters. The areoles bear small, slender spines that are more prominent on new growth and may become deciduous with age. The funnelform, nocturnal white flowers open for a single night, emitting a subtle fragrance 2.
Cultivation
In cultivation, it requires a very porous gritty mix to ensure rapid drainage. Unlike desert cacti, it prefers bright, filtered light over scorching, direct midday sun. Water thoroughly during the active summer growth period only when the soil is dry, and keep almost dry in winter 1.
Common Cultivation Errors
Excessive watering and heavy, clay-rich soils are the main causes of root rot. Cold drafts combined with wet soil in winter will quickly damage the root system and cause unsightly fungal lesions on the stems.
Bibliography
References
- Plants of the World Online (POWO), Royal Botanic Gardens, Kew. (http://www.plantsoftheworldonline.org) ↩
- GBIF Secretariat (2023). GBIF Backbone Taxonomy. (https://www.gbif.org) ↩
Watering
10-30 Days
Allow the substrate to dry out entirely between waterings. Reduce significantly in winter.
Soil
Well-draining cactus mix rich in pumice and coarse sand
Mineral-rich soil containing pumice, perlite, and coarse sand for rapid drainage.
Safety
Contact/Ingestion Risk
Possesses small, fine spines on younger stems. Keep away from curious pets.
Difficulty
Moderate
Moderate. Requires careful monitoring of soil moisture, especially in winter.
Native Habitat
Mexico (Guerrero, Jalisco, Michoacán, Oaxaca)
Found in the seasonally dry deciduous tropical forests of southwestern Mexico, typically growing semi-shaded on rocky hillsides and rocky substrates.
Frequently Asked Questions
How often should I water Acanthocereus tepalcatepecanus?
Water thoroughly during summer only after the soil has completely dried out (approx. every 10 days). In winter, reduce watering to once every 30-40 days.
What type of soil is best for this cactus?
A highly porous cactus mix containing 50% pumice, lava rock, or coarse sand is ideal. Avoid heavy garden soils that retain moisture.
Does it need direct sunlight?
Since it naturally grows in semi-shade, it prefers bright, filtered indirect light over intense, direct midday sun.
Is it toxic to pets?
While not inherently toxic, its small, fine spines can cause physical irritation to pets' mouths and paws, so caution is advised.
When and how does this cactus bloom?
Once mature, it produces large, funnelform white flowers that open at night during summer and close by early morning.
How fast does it grow?
Due to its scrambling nature, it can grow relatively quickly during the active spring and summer season compared to globose cacti.
What is its cold tolerance in winter?
It tolerates temperatures down to 8°C (46°F). It is frost-sensitive and should be kept indoors during cold winter months.
When should I repot this cactus?
Repot in early spring when the roots begin to crowd the container, moving it to a slightly larger pot with excellent drainage.
What causes the stems to soften?
Softening stems are usually a sign of root rot caused by overwatering. Stop watering immediately and take healthy cuttings if necessary.
Is it easy to propagate from cuttings?
Yes, stem cuttings taken in spring or summer root easily after being allowed to callus for a few days before planting in gritty soil.