Light
Bright Indirect Light
Requires bright filtered sun or several hours of direct morning sunlight daily.
Reference image Cereus lasianthus
Woolly-Flowered Cereus
Overview
Cereus lasianthus is a distinctive yet lesser-known columnar cactus species belonging to the family Cactaceae. Known for its vertical, ribbed growth habit, it is particularly admired by collectors for the woolly or hairy characteristics found on its flower tubes and areoles.
Taxonomy and Naming
Originally classified within the genus Cereus, the specific epithet "lasianthus" is derived from the Greek words "lasios" (woolly or shaggy) and "anthos" (flower) 1. Taxonomically, while many related species have shifted between genera, it remains historically linked to the core Cereus lineage due to its floral morphology 2.
Distribution and Habitat
While global locality data is scarce, like most members of the Cereus genus, it is native to the semi-arid valleys, rocky hillsides, and dry deciduous scrublands of South America. It has adapted to withstand prolonged dry spells and intense daily temperature fluctuations.
Appearance
The stems are green to bluish-green, featuring prominent ribs adorned with spiny areoles. The spines are typically greyish-brown and rigid. Its nocturnal flowers are particularly striking, covered in dense, woolly hairs along the floral tube, which protects them prior to blooming.
Cultivation
In cultivation, it requires a highly porous, mineral-rich substrate. Watering should follow the soak-and-dry method during spring and summer, while winter watering should be minimal to non-existent. It thrives under bright, filtered sunlight and benefits from good air circulation.
Common Cultivation Mistakes
Overwatering in poorly draining soil is the most common cause of failure, quickly leading to root rot. Keeping the cactus in damp, cold conditions during winter dormancy can also induce fatal fungal infections.
References
Watering
10-25 Days
Allow soil to dry out 100% between waterings. Water sparingly in winter.
Soil
Well-draining cactus mix with pumice and coarse sand
Use a specialized fast-draining gritty mix with plenty of pumice or perlite.
Safety
Pet Friendly
Spines are sharp and can cause injury. Handle with care using gloves.
Difficulty
Easy
Very easy to maintain as long as overwatering is strictly avoided.
Native Habitat
South America
Native to the semi-arid, rocky slopes and dry open plains of South America.
Frequently Asked Questions
Is Cereus lasianthus toxic?
No, it is non-toxic, but the sharp spines pose a physical injury hazard to pets and children.
How often should I water it?
Approximately every 10 days in summer and almost not at all in winter. Never water before the soil is bone-dry.
Which soil is best for pot cultivation?
A highly draining cactus mix containing pumice, coarse sand, and a minimal amount of peat moss is ideal.
Where should it be placed indoors?
An south- or west-facing window that receives plenty of bright light and has good air circulation is best.
Does it produce flowers?
Yes, mature plants produce large, nocturnal whitish flowers with a woolly outer tube during summer nights.
What is its growth rate?
Like most columnar cacti, it is slow to moderate growing, putting on a few centimeters of height per year under optimal conditions.
What winter temperatures can it tolerate?
It can tolerate temperatures down to 5°C (41°F) for short periods, provided the soil is kept completely dry.
When should I repot this cactus?
Typically in spring, every 2-3 years, or when the roots begin to crowd and escape through the drainage holes.
What should I do if the stem gets soft?
A soft stem is a sign of rot from overwatering. Stop watering immediately; if advanced, take healthy cuttings to root them.
Should I fertilize during summer?
Yes, you can apply a half-strength balanced liquid cactus fertilizer once a month during spring and summer.