Astrophytum myriostigma 'Onzuka'
Astrophytum myriostigma 'Onzuka' is an attractive, slow-growing cactus with a green, solitary stem heavily marked with white spots. The stem is globular to short cylindrical and usually has five ribs. The markings vary from plant to plant.
The glossy yellow flowers are funnel-shaped and appear from the areoles at the tip of the stem from spring to fall.
USDA hardiness zones 10a to 11b: from 30 °F (−1.1 °C) to 50 °F (+10 °C).
How to Grow and Care
Astrophytums are not vigorous plants, requiring a lot of patience to reach their full potential. Keep regularly watering and feeding them during the growing season and repot annually to give them space to develop. They need a temperate, dry winter, and make sure not to overwater them to avoid rotting their roots. They will develop marvelous flowers if given sufficient care once they reach maturity. Watch out for common cactus pests like aphids and scale, as well. These can often be taken care of by a good eco-friendly pesticide or simply wiped away with a cloth.
Repot regularly to help them develop. Astrophytums should be repotted at the beginning of the growing season for best results, allowing them to grow into the impressive specimens for which the genus is known. Protect your hands before repotting due to their stiff spikes, lift the plant out all at once, and then replace them in a larger pot and backfill with soil. Don't overwater or overfeed newly repotted cacti, as disturbances can be hard on them.
Learn more at How to Grow and Care for Astrophytum.
Astrophytum myriostigma 'Onzuka' is one the most striking cultivars of Astrophytum asterias. It was selected in Hiroshima, Japan, around 1974-1977. It was named for Mr. Tsutomu Onzuka, who reportedly raised this cultivar.
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