Origin and Natural Habitat
This species of Sulcorebutia is indigenous to Bolivia and only occurs in one very small locality.
Plant Characteristics
Sulcorebutia arenacea is a globular cactus with spider-shaped spines. It produces bright yellow flowers in spring and summer.
Care Guide
Light
This particular Sulcorebutia is not fussy. It can tolerate full morning sun if carefully adjusted to it, but a plant grown in some shade or a newly replanted specimen should not be placed in full sun immediately. It is best to grow them under 40% shade cloth.
Soil
Sulcorebutia arenacea prefers a gritty, inorganic soil medium that drains well, such as Ibaraki Akadama or Hyuga pumice.
Water
You should thoroughly soak the soil when watering. Only water this species in the spring and summer growing season, and keep dry in winter. Watering this plant in winter will cause it to rot.
Pot size
Sulcorebutia arenacea are medium sized cacti when mature. This species tends to remain solitary and does not easily produce offshoots. Small plants can be grown in 10cm pots until they start to grow near the edges of the pot, at which point they can be moved to larger pots. They should only be planted in a pot that is 3-5cm wider than their stem diameter.
Temperature
This species’ ideal temperature ranges between 20 – 30*C. It can tolerate 5 – 35*C. It is sensitive to frost.
Humidity
Sulcorebutia arenacea are sensitive to high levels of humidity, particularly during winter. Make sure that your growing space has plenty of airflow.
Fertilizing
Use a half-strength diluted general liquid fertilizer only during the growing season. Do not fertilize during autumn or winter. Alternatively, a small amount of slow-release fertilizer will be sufficient.
Growing Season
Sulcorebutia arenacea grow actively in spring and summer, and are fully dormant in autumn and winter.
In South Africa, their growing season is from September until late March.
Propagation
Sulcorebutia arenacea are best propagated from seed.
Seed germination: Seeds should be sown in early spring. Plant them in a coco peat based mix in an airtight container. Once most of the seeds have germinated, remove the lid of the container to allow airflow. Gently mist the seedlings every few days so that the soil does not dry out.