The “tennis ball plant” (Euphorbia obesa) is a distinctive succulent prized for its striking spherical form. Native to South Africa, its unique, symmetrical appearance often resembles a baseball or a stitched sphere, making it a captivating addition to any indoor plant collection.
Essential Care Guide
The tennis ball plant thrives in bright, indirect sunlight, ideally near a south or west-facing window filtered by a sheer curtain. Direct, intense afternoon sun can scorch its surface, causing discolored patches. Insufficient light can cause the plant to stretch and lose its compact, spherical form. Rotating the plant periodically helps ensure even light exposure and symmetrical growth.
Due to its succulent nature, careful watering is crucial to prevent rot. Allow the soil to dry out completely between waterings, which often takes several weeks. When watering, thoroughly drench the soil until water drains from the bottom of the pot. During its dormant period in winter, significantly reduce watering, perhaps to once every month or two, or suspend it entirely if temperatures are cool.
A well-draining, gritty soil mix, specifically formulated for cacti and succulents, is essential for proper drainage. This type of mix typically contains sand, perlite, or pumice, which prevents water from lingering around the roots. Standard potting soil retains too much moisture and can quickly lead to fungal diseases or rot.
The tennis ball plant prefers average room temperatures, generally ranging from 65 to 80 degrees Fahrenheit (18-27°C). It can tolerate slightly cooler temperatures during its winter dormancy but should be protected from freezing conditions. Average household humidity levels are suitable, as this plant does not require high moisture in the air.
Fertilize sparingly due to the plant’s slow growth rate. During the active growing season (spring and summer), apply a highly diluted succulent-specific fertilizer once every few months. Use a quarter or half strength of the recommended dosage. Avoid fertilizing during the fall and winter months when the plant is dormant.
Unique Growth Habits and Features
Spherical Shape
The tennis ball plant is known for its nearly perfect spherical shape, most pronounced in younger specimens. As the plant matures, it may slowly elongate, developing a slightly cylindrical form while retaining its distinctive ribbed structure. This gradual change in shape is a natural part of its aging process.
Slow Growth and Flowering
Growth for Euphorbia obesa is notably slow, often adding only a small amount of size each year. This deliberate pace contributes to its compact nature. Its unique flowering process involves small, inconspicuous flowers, known as cyathia, which emerge from the central groove at the plant’s apex.
Dormancy
The tennis ball plant undergoes a natural dormancy period, typically during the cooler, darker winter months. During this phase, its growth significantly slows or may even halt entirely. This is a normal physiological response, conserving energy until more favorable growing conditions return in spring.
Propagation and Repotting
Propagation
Propagating Euphorbia obesa is primarily achieved through seeds, produced after successful pollination. Seeds can be sown in a well-draining, gritty mix and kept warm and moist until germination, which can be a slow process. Mature plants may occasionally produce small offsets or “pups” around their base, which can be carefully removed and rooted independently. When handling the plant, exercise caution as it contains a milky white sap that can be irritating to skin and eyes.
Repotting
Repotting is an infrequent task for the tennis ball plant due to its slow growth and compact root system. It typically only needs repotting every two to three years, or when it becomes visibly root-bound. When repotting, select a container that is only slightly larger than the previous one, perhaps one inch wider in diameter. Ensure the new pot has ample drainage holes to prevent waterlogging.
Troubleshooting Common Issues
Rot
Rot is a prevalent issue, almost always a consequence of overwatering. Signs include a soft, mushy texture, discoloration ranging from dark brown to black, and a foul odor. If caught early, the affected parts can sometimes be removed, and the plant allowed to dry out extensively before any further watering.
Insufficient Light
Insufficient light often leads to stretching, also known as etiolation, where the plant elongates and loses its characteristic spherical shape. This results in a weaker, less attractive specimen as the plant attempts to reach for more light. Moving the plant to a brighter location, ideally with several hours of bright, indirect light daily, can prevent further etiolation, though existing stretched growth will not revert.
Pests
While generally robust, the tennis ball plant can occasionally be susceptible to common succulent pests such as mealybugs or spider mites. These pests typically appear as white, cottony masses or fine webbing on the plant’s surface. A gentle wipe with a cotton swab dipped in rubbing alcohol can often dislodge mealybugs, while a strong spray of water can help dislodge spider mites.
Slow Growth
A lack of noticeable growth is a common concern, but Euphorbia obesa is a naturally slow-growing species. During its natural dormancy period in winter, growth will naturally slow or cease entirely. This phase is a normal part of its life cycle and indicates the plant is conserving energy.