“inermis” meaning "unarmed,
weaponless, defenceless; toothless; stingless, spineless”
(The specific name implies: “not
It is a small
globose cactus, in age it forms nice
Spherical, of a fresh green colour.
Spineless with a short white
wool, they are arranged geometrically
and contrast with the stem .
Usually absent, a few small
bristly spines are occasionally produced
in the flowering areoles.
anther of a bright contrasting red.
This is a very distinctive plant even without flowers. It’s very
different from the common long and dense
is easy to grow. It
prefers a neutral to slightly acidic
mineral-based potting mix with a good
It likes a warm bright location, does great in partial shade but doesn't like
full, hot blazing sun in the central summer month.
Can support quite some water during the growing season
but pot plants in winter are
needs to be kept
dry (rots easily if soil is wet and cold) tends to lose
its roots in winter.
Usually it is recommended to
this plant in a bright and warm greenhouse with at least 8-10° C ,
but it has proved to tolerate temperatures as low as -5° C for short
This plant can be propagated only vegetatively by