The Split Rock succulent, Pleiospilos nelii, is a unique plant known for its distinctive pebble-like appearance. Native to the arid regions of South Africa, this succulent mimics its stony habitat. Its compact, low-growing habit and thick, fleshy leaves form a central cleft, giving it the common name “Split Rock”.
Mastering the Splitting Cycle and Watering
The Split Rock succulent’s care centers on its unique growth and splitting cycle. New leaves emerge from the center of the existing pair, gradually replacing the old ones. During this period, the plant absorbs water and nutrients from the older leaves, which shrivel and dry out.
Watering must be strictly controlled to support this natural absorption. Do not water when the plant has more than two pairs of leaves, or when new leaves are emerging and old ones are actively being absorbed. Overwatering during this phase is the primary cause of rot, as it prevents old leaves from being properly reabsorbed. A healthy Split Rock typically maintains one to two pairs of leaves.
Water sparingly, only when old leaves have completely shriveled and absorbed, and the plant shows signs of thirst, such as soft or wrinkled innermost leaves. This might mean watering only a few times a year, allowing the soil to dry out completely between waterings.
Ideal Growing Conditions
Split Rock succulents thrive in specific environmental conditions that mimic their native South African desert habitat. Providing the right balance of light, soil, temperature, and humidity is important for their long-term health.
Light
These succulents require bright, direct sunlight for healthy growth, ideally receiving at least four to six hours daily. Placing them in a south-facing window indoors or a sunny outdoor location is suitable. While they benefit from ample light, protect them from intense, direct afternoon sun to prevent sunburn. If a new plant is brought home, gradually acclimatize it to brighter conditions over several days or weeks.
Soil
Extremely well-draining, gritty soil is essential for Split Rock succulents to prevent root rot. Amend a commercial cactus or succulent mix with a large amount of inorganic materials. Components like perlite, pumice, or coarse sand are good additions, making up a large portion (e.g., 75-90%) of the mix. Always use pots with drainage holes to allow excess water to escape.
Temperature and Humidity
Split Rock succulents prefer warm, dry conditions. They thrive in room temperatures between 60°F to 80°F (16°C to 27°C) during the day. While they tolerate heat, they are not frost-tolerant and should be protected from temperatures below 50°F (10°C). High humidity is detrimental and can lead to fungal issues and root rot.
Repotting and Feeding
Split Rock succulents do not require frequent repotting due to their slow growth rate and preference for being somewhat root-bound. Repotting is necessary only every few years (e.g., three to five years), or when the plant has outgrown its container. When repotting, do so gently to minimize root disturbance. Ensure the new pot has drainage and is filled with a well-draining soil mix.
These plants have low nutrient requirements and rarely need fertilizer. If fertilizer is used, apply a highly diluted (e.g., quarter strength) low-nitrogen succulent fertilizer sparingly. This should only be done during the active growing season in spring, and never during dormancy or when the plant is actively splitting. Over-fertilization can lead to weak growth and interfere with the plant’s natural splitting cycle.
Addressing Common Issues
Several common problems can arise with Split Rock succulents. Recognizing these issues early can help address them effectively. Most problems relate to environmental factors and watering practices.
Overwatering
If leaves become soft, mushy, or discolored, it indicates overwatering. This is the most common cause of decline and can quickly lead to root rot. If detected, cease watering immediately. The plant may need to be unpotted to allow roots and soil to dry thoroughly.
Insufficient Light
Stretching or etiolation, where the plant appears elongated with widely spaced leaves, signals insufficient light. Moving the plant to a brighter location is the solution, though existing etiolated growth will not revert to its original compact shape.
Not Splitting
If the plant is not splitting, or develops multiple pairs of leaves without the older ones being absorbed, it indicates improper watering or over-fertilization. The plant needs to be “stressed” by lack of water to encourage the reabsorption of older leaves and the emergence of new ones.
Underwatering
While shriveling or wrinkling of outer leaves is a normal part of the splitting cycle, if the entire plant appears shriveled or wrinkled when not actively splitting, it suggests underwatering or extreme heat. Check soil moisture and carefully water, ensuring the soil is completely dry first, to rehydrate it.