Gymnocalycium horstii | Mother-of-pearl sphere
€7,95
Gymnocalycium horstii Buining · Mother-of-pearl Sphere · Spider Cactus
🌱 Morphology
A large, globose Gymnocalycium, initially solitary and capable of forming small clusters with age. The body, bright green with a smooth epidermis, can reach about 20–25 cm in diameter. It features 5–6 wide, rounded, and deeply transversely furrowed ribs. The areoles usually produce 5 radial spines, white or pale yellow, slightly curved and extended like a spider's legs; one often points downward. The spines reach about 3 cm. The flowers are extraordinarily large for the genus, reaching up to 11 cm in length and diameter.
🌍 Distribution, habitat, and family
Endemic to Rio Grande do Sul, Brazil, where it grows on rocky sandstone outcrops within the Brazilian Pampa grasslands, generally protected among rocks, shrubs, and light shade. It is found up to approximately 300–400 m in altitude. It belongs to Cactaceae, Cactoideae. Joël Lodé maintains Gymnocalycium horstii and separates G. buenekeri as a species, while other classifications treat it as a subspecies of G. horstii.
❄️ Temperature · USDA Zone 8b
It tolerates minimum temperatures of up to −8 ºC when kept dry and with well-acclimated specimens. In cultivation, it is advisable to avoid low temperatures coinciding with moist substrate.
☀️ Lighting
It prefers very intense but filtered light, avoiding direct sun during the hottest central hours, which can cause burns or tanning of the epidermis. Approximate PAR DLI of 15–25 mol·m⁻²·day⁻¹.
💧 Growth cycle and watering
Winter rest. It is kept practically dry during the cold period. From spring to the end of summer, it tolerates and appreciates regular watering, but always spaced out, allowing the substrate to dry. Its habitat receives more seasonal humidity than many arid zones where other cacti live.
🌸 Flowering
It blooms approximately from 5–8 years of age under good cultivation conditions. Flowering is concentrated between May and July in the Northern Hemisphere. The flowers, white, cream, or soft pink, can reach 11 cm, and a mature plant can produce successive flowers during the season. The reproductive biology is particular: functionally male and female flowers have been described, so it should not be considered a universally self-fertile species.
🌿 Nutrition
During the active growth period, a fertilizer with high content of assimilable calcium and low nitrogen levels is recommended, such as Desert CHOICE® Cactaceae, applied once a month when watering. Before flowering, it can be supplemented with Desert CHOICE® Flowering.
This is an inimitable xerophyte grown in Madrid in a technological square pot and with the substrate activated with mycorrhizal fungi and biofungicides.
📏 The sizes of our basic collection xerophytes are as follows:
S -> 9cm x 9cm
M-> 14cm x 14 cm
L->16cm x 16 cm
* As this is an online purchase, the appearance of the sent specimen may vary slightly from the product image. The plant measurements are specified in the photo description, but this may also vary slightly because it is a living being! Each of the plants at Desert CITY has unique characteristics.
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