Light
Filtered Sun
Prefers bright, filtered sunlight or light shade; avoid scorching midday sun.
Reference image Frailea alexandri
Alexander's Frailea
Overview
Frailea alexandri is a highly sought-after, miniature succulent subshrub in the family Cactaceae. Known for its extremely compact growth habit and its ability to produce cleistogamous flowers, this tiny cactus spends much of its life partially subterranean in its natural habitat to survive harsh periods 1.
Taxonomy and Naming
The genus Frailea was established to honor Manuel Fraile, who curated the cactus collection of the US Department of Agriculture. The specific epithet alexandri honors a historical botanical collector or taxonomist associated with its discovery in South America 2.
Distribution and Habitat
Native to southern South America, particularly southern Paraguay, Frailea alexandri thrives in subtropical biomes. It typically colonizes stony grasslands, rocky crevices, and thin soils over granite outcrops, where it is often sheltered from intense direct sun by surrounding vegetation.
Appearance
This globose to shortly cylindrical cactus features a flattened dark green to bronzy-purple stem. It remains small, often under 3-4 cm in diameter. The ribs are low and tubercled, bearing tiny, pectinate spines pressed closely against the stem. The flowers are pale yellow and frequently set seed without opening (cleistogamy) 1.
Cultivation
In cultivation, it requires a highly porous, mineral-rich substrate with superb drainage. Watering should be deep but infrequent during summer, with a dry winter rest. Filtered light helps the plant develop its signature dark or reddish-bronze epidermal coloration.
Common Cultivation Mistakes
Overwatering is the primary cause of failure, quickly leading to root and stem rot. Using standard potting soils with high organic matter, or exposing the plant to freezing temperatures while wet, will also result in plant loss.
References
Watering
6-25 Days
Water moderately in summer once soil dries out; keep completely dry in winter.
Soil
Well-draining, gritty, acidic cactus soil mix with pumice and sand
Requires extremely porous, mineral-based cactus mix with high grit and pumice.
Safety
Pet Friendly
Non-toxic to pets; the tiny, soft spines pose virtually no physical danger.
Difficulty
Moderate
Moderate care level due to strict watering requirements and rot sensitivity.
Native Habitat
Paraguay and Southern South America
Naturally occurs in subtropical grasslands and rocky crevices on granite formations within Paraguay and adjacent regions.
Frequently Asked Questions
Can Frailea alexandri be grown indoors?
Yes, its miniature size makes it an excellent indoor cactus for sunny windowsills and small containers.
How often should it be watered?
Water approximately every 6 days in summer only after the soil has dried out completely, and keep it dry in winter.
What type of soil does it require?
It requires a highly porous, acidic cactus mix with low organic matter and high amounts of pumice, grit, and coarse sand.
Why do the flowers set seed without opening?
Cleistogamy is common in Frailea; the flowers self-pollinate while closed and turn into seed pods. They only open fully on very hot, sunny days.
Is it toxic to pets?
No, *Frailea alexandri* is completely safe and non-toxic to cats, dogs, and other household pets.
What is the minimum winter temperature it can tolerate?
It can tolerate brief drops to 5°C if kept completely dry, but a winter temperature of 8-12°C is optimal.
How fast does it grow?
It is a very slow-growing cactus that can stay in the same small pot for years, rarely exceeding 4-5 cm in diameter.
When should it be repotted?
Its roots are delicate. Repot only every 2-3 years in early spring when the plant completely outgrows its pot.
Are the spines sharp or dangerous?
No, the spines are very small, soft, appressed to the body, and do not prick or damage the skin.
What is the most common cause of death?
The most common cause is root rot due to overwatering, stagnant air, or leaving the soil wet during cold winter months.