Astrophytum Myriostigma cv. Onzuka

Astrophytum Myriostigma cv. Onzuka

You will receive this exact large specimen with pups!
Measures 4" wide x 4" tall above the soil line.
Showcased here in one-of-a-kind handmade pottery (sold separately).   
Roots as shown.
Please note that the pups may disconnect during shipping as their connection to the main body is tenuous but if this should happen, just plant the pup(s) and grow new onzukas!
Will be shipped bare root.

Astrophytum myriostigma cv. 'Onzuka', also known as Bishop's Cap or Bishop's Hat cactus 'Onzuka', is a highly prized cultivated variety of the Astrophytum myriostigma species.  It is a popular choice for collectors due to its rarity, unique features and relatively easy care. 
 

Here's a breakdown of its key characteristics:

·        Origin and History: While the wild species originates from Mexico, the 'Onzuka' cultivar was developed in Hiroshima, Japan, between 1974 and 1977 by Mr. Tsutomu Onzuka, for whom it is named.

·        Appearance:

o   Stem: This slow-growing cactus has a green, solitary stem that is typically globular to short cylindrical.

o   Ribs: It usually possesses five wide ribs, giving it a star-like shape, but forms with four ribs ("quadricostatum") also exist.

o   Markings: The most striking feature of the 'Onzuka' is its heavily speckled, snowy-white epidermis, which is much thicker and more pronounced than the typical species. These markings can vary greatly between individual plants and develop over time. Some cultivars even display V-shaped markings along the rib edges.

o   Spines: Generally, 'Onzuka' is a spineless cactus.

·        Flowers: It produces shiny yellow, funnel-shaped flowers, approximately 3 inches long, from the areoles at the top of the stem during spring and summer.

·        Care:

o   Light: Requires bright sunlight, preferably with direct exposure. In very hot climates, afternoon shade may be beneficial to prevent sunburn.

o   Watering: Needs very well-draining soil and infrequent watering to prevent root rot, as it is highly sensitive to wet conditions. Water deeply when the soil is completely dry. Reduce watering significantly in winter, keeping the soil dry.

o   Soil: A well-draining cactus and succulent mix with at least 70-80% mineral grit (e.g., coarse sand, pumice, perlite) is essential.

o   Fertilization: 'Onzuka' grows slowly and does not require frequent fertilization. Replacing the potting soil annually should be sufficient. If desired, use a low-nitrogen fertilizer during the summer growing season to encourage faster growth.

o   Temperature: This cactus is not tolerant of hard frost. It can be brought indoors in freezing temperatures. It is hardy to about 20°F (-7°C) for short periods. During the winter dormancy, temperatures between 40 and 60°F (5 to 15°C) are ideal.

o   Repotting: Repot at the beginning of the growing season (spring) every 2-3 years to allow for root development and growth.

·        Propagation: Primarily by seeds, although crested forms are often grafted onto columnar cacti. 

Important Notes:

·        Overwatering: This is the most common cause of problems with Astrophytum myriostigma 'Onzuka'. Its harder epidermis is prone to cracking if overwatered.

·        Variations: Numerous cultivars of 'Onzuka' exist, exhibiting variations in the intensity and patterns of white flecking, and even different forms such as the columnar form.

·        Rarity: Crested forms are particularly rare and sought after.