The Notocactus haselbergii, commonly known as the Scarlet Ball Cactus, is a captivating and popular species among cactus enthusiasts. This charming plant is recognized for its compact size and vibrant flowers, making it a delightful addition to any collection. Native to the grasslands and rocky outcrops of Brazil, particularly in the states of Rio Grande do Sul and Santa Catarina, it thrives in its natural environment at elevations between 500 to 1200 meters above sea level. Its former classification as Notocactus haselbergii and its current accepted name, Parodia haselbergii, both refer to this same attractive specimen. The Scarlet Ball Cactus is well-suited for beginners due to its relatively straightforward care requirements and offers significant ornamental value with its striking appearance.
Identifying Notocactus haselbergii
The Notocactus haselbergii typically presents as a solitary, globular to somewhat flattened spherical cactus, reaching up to 10-12 cm in height and 10-15 cm in diameter. Its stem is bright green, often almost entirely concealed by its dense spination. The plant features numerous low ribs, sometimes exceeding 30, and its areoles are covered with short, white wool.
The spines are soft and bristly, primarily silvery-white, sometimes with a yellowish tip, contributing to its distinctive fluffy appearance. What truly distinguishes this cactus are its spectacular flowers, emerging in clusters near the apex of the plant. These funnel-shaped blooms are typically bright orange to brick-red, often with golden-yellow stamens, and can measure up to 2.5 cm in diameter. They typically appear in late winter or early spring and can last for several weeks, with individual flowers remaining open for up to two weeks or more.
Notocactus haselbergii Care
Light
Providing appropriate light is important for the health and flowering of Notocactus haselbergii. This cactus thrives in bright, indirect light conditions. While it can tolerate some direct morning sun, particularly in cooler climates, intense afternoon sun can lead to scorching and damage the plant’s epidermis.
Insufficient light can cause the cactus to stretch and become etiolated, resulting in a pale, elongated appearance and poor flower development. Placing it near a south-facing window with some protection from harsh midday sun, or in a bright, east-facing location, generally provides ideal conditions. Rotating the plant periodically ensures even growth and light exposure on all sides.
Watering
Proper watering techniques are important for the survival of Notocactus haselbergii. The “soak and dry” method is recommended, where the soil is thoroughly watered until it drains from the bottom, then allowed to dry completely before the next watering. During its active growing season from spring through summer, watering should be more frequent, typically once every 7 to 10 days depending on environmental conditions.
As temperatures cool in autumn and winter, the plant enters a dormant phase, requiring significantly less water or none at all. Overwatering, especially during dormancy or when temperatures are low, is a primary cause of root rot, which can quickly lead to the plant’s death. Ensuring excellent drainage and allowing the soil to dry out prevents this common issue.
Soil Requirements
The right soil mix is important for the health of Notocactus haselbergii, as good drainage is essential to prevent root rot. A specialized cactus or succulent mix is highly recommended due to its gritty, fast-draining properties. Such mixes typically contain components like perlite, pumice, coarse sand, or small gravel, which enhance aeration and drainage.
These materials prevent water from sitting around the roots, mimicking the arid, well-drained conditions of the plant’s natural habitat. A slightly acidic to neutral pH is generally preferred for optimal nutrient uptake. Avoiding heavy, moisture-retentive garden soil is important, as it can suffocate roots and promote fungal diseases.
Temperature and Humidity
Notocactus haselbergii prefers warm temperatures during its active growth period in spring and summer, ideally between 20-30°C (68-86°F). To encourage flowering, a cooler, dry dormancy period in winter is beneficial, with temperatures ideally dropping to around 7-10°C (45-50°F). This species is not frost-tolerant and requires protection from freezing temperatures, though it can tolerate short periods as low as -5°C (23°F) if kept dry.
While it can tolerate average household humidity levels, high humidity can be problematic, especially when combined with cool temperatures, as it increases the risk of fungal issues. Adequate air circulation is important to mitigate humidity-related problems, particularly in enclosed spaces. Providing a consistent temperature gradient between seasons helps support its natural growth cycle.
Fertilizing
Fertilizing Notocactus haselbergii during its active growing season supports robust growth and prolific flowering. A low-nitrogen, high-potassium fertilizer formulated for cacti and succulents is suitable. It should be applied sparingly, typically once every two months during the growing season, diluted to half or quarter strength to avoid over-fertilization, which can burn the roots.
Over-fertilization can lead to excessive, weak growth and may hinder flowering. During the dormant winter months, fertilization should be completely withheld, as the plant is not actively growing and cannot properly utilize the nutrients. Resuming fertilization only when new growth appears in spring ensures the plant is ready to absorb nutrients.
Flowering and Repotting
Encouraging Notocactus haselbergii to flower involves providing a cool, dry winter dormancy, followed by bright light and increased watering in spring. The vibrant orange to brick-red blooms typically appear from late winter to early spring, often lasting for several weeks. Adequate light exposure during the growing season is crucial for bud formation.
Repotting is generally necessary every 2-4 years, or when the cactus becomes root-bound, indicated by roots growing out of the drainage holes. The best time to repot is early spring before the active growing season begins. When repotting, ensure the soil is dry and handle the plant carefully using gloves to protect against spines. Using a pot only slightly larger than the previous one and a fresh, well-draining cactus mix helps the plant settle quickly.
Propagating Notocactus haselbergii
Propagating Notocactus haselbergii is primarily achieved through seeds, as it rarely produces offsets or “pups.” Propagating from seeds is a slower but rewarding process. To propagate from seeds, sow them on the surface of a sterile, well-draining cactus mix, lightly covering them with fine grit. Maintain warmth, ideally between 21-27°C (70-80°F), and high humidity by covering the tray with plastic or glass to keep seeds moist until germination. Germination typically occurs within 7 to 14 days, though it can take longer. Young seedlings require protection from direct sunlight.
If offsets do appear, carefully detach them from the mother plant. Allow them to callus for several days in a dry, airy location before planting in a well-draining cactus mix to root. Rooting hormone can be applied to the callused end to encourage faster root development.
Common Problems and Solutions
Root rot is one of the most frequent issues encountered with Notocactus haselbergii, primarily caused by overwatering, especially in poorly draining soil or during its dormant period. The solution involves ensuring excellent drainage, allowing the soil to dry completely between waterings, and reducing water significantly in winter. If rot is detected early, the affected parts can be trimmed away, and the healthy portion allowed to callus before repotting in fresh, dry soil.
Etiolation, characterized by stretched, pale growth, indicates insufficient light. Moving the plant to a brighter location with more intense, indirect light will prevent further stretching, though the elongated growth will not revert. Common pests like mealybugs or spider mites can sometimes affect Notocactus haselbergii. Mealybugs appear as white, cottony masses, while spider mites cause stippling on the plant’s surface and fine webbing. Treating these pests with insecticidal soap or a diluted rubbing alcohol solution applied with a cotton swab can effectively eradicate them. Regular inspection helps catch infestations early.