Light
Full Sun
Enjoys direct and bright full sun; low light causes the stems to stretch and thin.
Reference image Harrisia adscendens
Climbing Harrisia
Overview
Harrisia adscendens is a scrambling or semi-erect, succulent subshrub in the family Cactaceae 1. Native to the arid Caatinga region of Brazil, it is characterized by its slender, spiny branches and large, night-blooming flowers.
Taxonomy and naming
Originally described as Cereus adscendens, it was later moved to the genus Harrisia by Britton & Rose 2. In its native Brazil, it is commonly known as "cofre" or "mandacaru-de-veado".
Distribution and habitat
This species is endemic to northeastern Brazil, including states such as Bahia, Ceará, Pernambuco, and Piauí 1. It thrives in seasonally dry tropical forests and the thorny Caatinga scrubland, growing among rocks and shrubs.
Appearance
The cylindrical, green stems can reach up to several meters, often scrambling over surrounding vegetation. Stems have 7 to 10 low ribs with sharp, yellowish-brown spines. The large, tubular, white flowers open at night to attract bat and moth pollinators 2. Its globose fruits are bright red and covered with small spines.
Cultivation
In cultivation, Harrisia adscendens requires a position in full sun to partial shade and a very well-drained, mineral-rich gritty soil. Water deeply but allow the medium to dry out completely between waterings. During winter, reduce watering significantly.
Common cultivation mistakes
The most common mistake is overwatering, which quickly leads to root rot. Insufficient sunlight causes etiolation, where the plant becomes weak, pale, and stretched out.
References
Watering
7-25 Days
Allow the potting mix to dry out completely before watering; reduce water to a minimum in winter.
Soil
Fast-draining, gritty and sandy cactus mix
Coarse, well-drained potting mix with high mineral content like pumice and sand.
Safety
Contact/Ingestion Risk
Equipped with numerous sharp spines; keep out of reach of children and domestic pets.
Difficulty
Moderate
Easy to moderate, provided it receives sufficient light and is not overwatered.
Native Habitat
Brazil
Distributed across the semi-arid Caatinga ecosystems of northeastern Brazil, where it climbs over other scrub vegetation or grows openly on rocky soils.
Frequently Asked Questions
Can Harrisia adscendens be grown indoors?
Yes, but due to its high light requirements, it must be placed directly in front of a sunny south- or west-facing window.
How often should I water it?
Water it when the soil is completely dry in summer (about once a week), and reduce watering drastically in winter (lightly once every 3-4 weeks).
What type of soil should I use?
Use a highly mineral-based cactus mix containing plenty of pumice, perlite, and coarse sand for excellent drainage.
When does it bloom?
It blooms during the summer, producing large, showy white-to-pinkish flowers that typically open at night.
How fast does it grow?
Compared to slow-growing cacti, it has a moderate growth rate, producing scrambling stems when provided with sufficient sun and warmth.
Is it toxic to pets?
While not chemically toxic, its sharp and stiff spines pose a severe mechanical injury hazard to curious pets.
When should it be repotted?
Generally every 2-3 years in spring. Always use thick protective gloves when moving it to a slightly larger pot.
Why are the stems getting thin and stretched?
This is a sign of insufficient light (etiolation). You should move the plant to a brighter spot with direct sunlight.
Is it cold hardy in winter?
No, it is sensitive to frost. It should be kept indoors or in a greenhouse where temperatures do not drop below 8°C (46°F).
How do you propagate Harrisia adscendens?
It can be propagated by stem cuttings. Allow the cut end to callus for a few days before planting it in well-draining soil.