Lithops, often called “living stones,” are unique succulent plants that blend seamlessly with their rocky, arid native environments. Their distinctive appearance, mimicking pebbles or stones, is a direct adaptation to their specific needs, particularly concerning water. Understanding the precise watering requirements of Lithops is paramount, as improper watering stands as the most common reason for their decline in cultivation.
The Lithops Watering Cycle
Lithops possess extensive root systems and remarkable water storage capabilities within their thick, fused leaves, allowing them to endure prolonged periods without rainfall. Their growth cycle is tied to seasonal changes, with distinct dormancy periods in summer and winter, and active growth phases in fall and spring. Summer brings extreme heat and drought, prompting dormancy to conserve moisture. Winter is also a dry dormant period when new leaves develop internally, absorbing water from old outer leaves.
Growth typically resumes in late summer to early fall, often marked by flowering, indicating a need for water. As winter approaches, new leaves emerge from the fissure, drawing moisture from the older leaves to fuel growth. During this “splitting” phase, old leaves shrivel and dry into a papery sheath; watering is suspended to allow this reabsorption. Water can resume in spring once old leaves are completely dry and shriveled.
Identifying Overwatering
An overwatered Lithops displays clear indicators of cell damage. Leaves may appear mushy, soft, translucent, or yellow. A swollen or bloated appearance is common as tissues become engorged. In severe cases, leaves might burst open, leaving jagged cuts or splits from internal pressure.
Overwatering frequently leads to root rot, manifesting as discoloration, a soft or mushy texture, and an unpleasant odor. The plant may also split apart.
Addressing Overwatering
Upon identifying an overwatered Lithops, immediate action is necessary, though recovery is not always guaranteed. Cease all watering to allow the potting medium to dry. Improve air circulation to evaporate excess moisture. If symptoms are severe or root rot is suspected, gently unpot the plant to inspect its root system.
Trim any brown, mushy, or foul-smelling roots with clean, sterile tools. Rinse healthy roots with lukewarm water and allow them to air dry for several hours or days to callous over. Repot into fresh, dry, highly gritty soil in a pot with adequate drainage, and refrain from watering until the plant stabilizes.
Identifying Underwatering
Underwatering manifests as distinct visual cues, indicating the Lithops is utilizing its stored water reserves. Common signs include shrunken, wrinkled, or flattened leaves. The plant may appear concave or deflated, particularly on its sides or top surface. These symptoms reflect a reduction in turgor pressure as cells deplete internal water.
If wrinkles are visible day and night, the plant needs water. An underwatered Lithops will feel soft to the touch, unlike the firm, plump texture of a well-hydrated specimen.
Addressing Underwatering
When a Lithops shows signs of thirst, a controlled, thorough watering is required. Provide a substantial drink, ensuring water reaches the roots, but avoid overcompensating. Bottom watering is effective: place the pot in a shallow tray of water for 15-20 minutes, allowing soil to absorb moisture from the drainage holes upwards. This ensures even saturation without drenching the crown.
After watering, remove the pot from the tray and allow excess water to drain. The plant should plump up and regain its firm appearance within a few days as it rehydrates. Monitor the plant closely after this corrective watering, resuming a regular schedule only when new signs of thirst reappear.
Best Practices for Watering Lithops
Proper watering for Lithops aligns with their natural growth cycle, emphasizing infrequent but thorough hydration during active periods and extended dry spells during dormancy. During the active growing season (late summer through fall), water only when the plant shows signs of thirst, such as visible wrinkling or softening. A “soak and dry” method is effective: water thoroughly until drainage, then allow soil to dry completely. Watering in the mornings allows excess moisture to evaporate quickly.
During the “splitting” phase in winter and spring, when new leaves form and absorb old ones, refrain from watering. Watering during this phase can disrupt the process, causing old leaves to rot instead of dry. Summer dormancy also requires minimal to no water, though a small sip can be given if the plant shrivels excessively due to extreme heat. Always err on the side of underwatering, as Lithops are more tolerant of drought than excess moisture.
The choice of growing medium and pot significantly influences watering success. Lithops require a well-draining, gritty soil mix, ideally with a high proportion of inorganic materials (e.g., pumice, perlite, decomposed granite), often 75% or more. Unglazed terracotta pots are preferred due to their porous nature, promoting evaporation and preventing waterlogging. Pots should be 3 to 5 inches deep to accommodate their taproot. Using rainwater or distilled water is recommended over tap water, especially if tap water is hard.