A small genus of two species, Neowerdermannia is a genus of spiny globose cacti which are very similar to the genus Gymnocalycium. Flowers are bourne near the apex and have naked floral tubes with scales – eiter white or pink. The fruits are globose and dehiscent.
The body features ribs which are not clearly defined and broken into rather pronounced tubercles. Areoles are small at the top of the tubercles (not the ends) and give rise to as many as 20 stout spines which may be curved or even hooked.
The plants in this genus are found in Argentina, Bolivia, Chile, and Peru, though apparently not in great numbers. It is even more scarce in cultivation and grown by enthusiasts, but not commercially.
Light: Suited for sunny-brightly exposure; can tolerate light shade.
Water: Watering in the summer months, while Neowerdermannias are growing well can be frequent (weekly for small plants in small pots), but always allowing the compost nearly to dry out before rewatering. Watering in the winter months at all is unwise, and certainly not necessary. The difficult times are spring and autumn.
Temperature: Neowerdermannias are very cold resistant as low as to 14° C (-10° C) or less for short periods of time.
Soil: The balance of the potting medium should be sufficient to allow good drainage, so that the plants do not sit in soggy soil for more than a day or two after watering.
Seeds, also can be grown from cutting or graft. Seeds can be sown in the spring or summer. The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots.
Pests and Problems
Neowerdermannias are especially prone to root rot, therefore, underpot in a smaller container filled with very porous compost.
Neowerdermannias come from mountainous areas, so like bright light, cool and dry conditions in the winter; this is important for the flowers as well as for their health. Without this cool winter period 32-50° F (0-10° C) they normally won't get many buds. They have a thick taproot and are of difficult cultivation and rot prone because of a great sensitivity to the excess of watering, not easy to get to any large size on their own roots really a challenge to grow into a large clump. Needs deep pot and good drainage to accommodate its tap root. They are commonly grafted to avoid root problems and to make easier to grow. On a graft Neowerdermannias are easier to grow, but the body splits if over-watered (especially in spring).