Gymnocalycium horstii is a globular cactus resembling a loaf of bread from a bakery. Plants have a squat appearance and spines that are curved back towards the body. Plants usually offset over time, creating interesting specimens. The body of this species is glossy and the flower is always white. Its close relative Gymnocalycium buenekeri which occurs 200 km westward has a very similar but dull body with always pink flowers. Gymnocalycium horstii occurs only in the southern Brazilian province of Rio Grande do Sul and has been considered endangered since 2010 due to wild specimens being collected for the plant trade.
Spider cactus is fairly disease-resistant and usually tolerates normal care without becoming ill easily. That said, it can be vulnerable to mealybugs; these pests may inflict some harm but are typically not a major danger. Regarding care, Spider cactus is drought-tolerant and does not need frequent watering. It can handle extended intervals without water and requires little fertilizer. However, it is very prone to root rot if kept in poor light and given too much water. In general, Spider cactus is a good choice for people who prefer low-maintenance plants, though it remains important to know and satisfy its basic needs. It is especially appropriate for individuals who are away for long stretches and might forget to water regularly.
How to keep Gymnocalycium Horstii.
Light
The spider cactus flourishes in full, direct sun but can tolerate partial shade. Seasonal changes may require moving potted plants from outdoors to indoors. Inadequate light causes weak growth and dulling of color.
Water
The spider cactus thrives in arid conditions, showcasing excellent drought tolerance. Adapted to store water efficiently, it only needs to be watered once every three weeks. To prevent root rot, it prefers well-draining soil and is typically grown outdoors.
Humidity
This plant prefers dry conditions, so don't mist it. However, watering it less often can also thrive in higher humidity.
Temperature
Spider cactus is indigenous to areas where temperatures usually range from 68 to 100 °F (20 to 38 ℃). Because it prefers warm conditions, temperatures should be adjusted carefully with the seasons to maintain the plant's health.
Fertilizer
Spider cactus only needs light applications of fertilizer once or twice a year during the growing season. Do not fertilize in winter or in summer when it is dormant. Cut back on fertilizer for plants that have been repotted and wait a few months after repotting before you start fertilizing again. Fertilizing helps maintain healthy growth and promotes flowering.
Pruning
The spider cactus needs very little pruning. Simply remove any withered flowers and branches to help the plant direct nutrients towards healthy growth.
Pot & Repot
Repot the spider cactus in spring or summer, selecting a pot only slightly larger than the current one that has good drainage. Use a well-draining, sandy or gritty cactus mix. Handle the plant carefully to avoid the spikes. Let the cactus dry out before repotting to help prevent root rot. After repotting, wait a week before watering so the roots can heal.
Botanical profile.
- Plant Type
- Succulent
- Life Cycle
- Perennial
- Hardiness Zone
- 10-11
- Mature Height
- 20 cm
- Mature Spread
- 25 cm
- Leaf Color
- Dark Green, Green
- Leaf Type
- Evergreen
- Flower Color
- White, Pink, Purple
- Flower Size
- 5.08 cm to 6.35 cm
- Bloom Time
- Late spring, Summer, Early fall
- Planting Time
- Spring, Summer, Autumn
- Harvest Time
- Late summer, Fall
Other names.
