The “ass plant,” commonly known as Lithops, is a unique succulent that captivates with its stone-like appearance. These fascinating plants are often referred to as “living stones” due to their remarkable camouflage, allowing them to blend seamlessly with their rocky surroundings. Native to the arid regions of southern Africa, Lithops have evolved distinctive features that enable them to thrive in harsh, dry environments.
What is an Ass Plant (Lithops)?
The common name “ass plant” is an informal reference to Lithops, a genus of succulent plants known for their resemblance to pebbles or stones. This mimicry is a natural adaptation that helps them avoid being eaten by animals in their native southern African habitats, including Namibia and South Africa.
Each Lithops plant consists of two fleshy, fused leaves forming an inverted cone with a fissure or split at the top, where new leaves and flowers emerge. Their coloring, which ranges from shades of gray, brown, rust, green, and pink, along with varied patterns of dots, lines, or patches on their upper surface, enhances their camouflage. The leaves are mostly buried beneath the soil, with a translucent top surface, often called a “leaf window,” allowing light to penetrate for photosynthesis. This unique morphology and ability to store water are key to their survival in dry, rocky terrains.
Ass Plant (Lithops) Care
Caring for Lithops requires specific environmental conditions that mimic their natural desert origins. Proper light, watering, soil, temperature, humidity, and minimal fertilization contribute to their long-term health.
Light
Lithops require very bright, direct sunlight to maintain their compact form and vibrant coloration. Placing them in a south-facing window is often ideal, providing four to five hours of direct sunlight, with partial shade during the hottest afternoon hours. Insufficient light can cause the plants to stretch and become elongated, a condition known as etiolation, which results in weak growth and a loss of their distinctive patterns. While they tolerate intense light, extreme heat can sometimes damage their foliage, so some protection might be needed during peak summer heat.
Watering
Precise watering is paramount for Lithops, as overwatering is the most common cause of their demise. These succulents store water in their thick leaves, allowing them to endure long periods without moisture. Water should only be given sparingly when the plant shows clear signs of thirst, such as slight wrinkling or shrinking of the leaf tops. It is crucial to allow the soil to dry out completely between waterings to prevent root rot. The specific timing of watering is closely tied to the plant’s unique growth cycle.
Soil
Lithops need an extremely well-draining, gritty soil mix to prevent waterlogged conditions that lead to rot. A specialized cactus or succulent mix is a good starting point, but it should be amended with additional inorganic materials such as pumice, coarse sand, perlite, decomposed granite, or crushed brick. The soil should have a very low organic content, ideally around 10-20% organic material, to best mimic their native rocky habitats. Pots should also have drainage holes and be deep enough to accommodate their extensive taproots.
Temperature and Humidity
Lithops prefer warm, dry conditions and can tolerate high temperatures, often up to 90-100 degrees Fahrenheit. They thrive in average household temperatures, typically between 65 to 80 degrees Fahrenheit. Good air circulation is beneficial, and they are not tolerant of high humidity. It is important to protect Lithops from freezing temperatures, moving them indoors if temperatures drop below 40 degrees Fahrenheit.
Fertilizing
Lithops have very low nutritional requirements and generally do not need frequent fertilization. They are adapted to nutrient-poor environments, and excessive nutrients can lead to undesirable rapid growth. If fertilizing, a very dilute, low-nitrogen, high-potassium liquid fertilizer can be applied during their active growth period. Some growers find that regular repotting every few years into fresh gritty mix provides sufficient nutrients without the need for additional feeding.
Understanding the Lithops Growth Cycle
The life cycle of Lithops is distinct and directly influences their care requirements, especially watering. These plants undergo yearly phases of growth, dormancy, and renewal.
During winter and early spring, new leaves grow from within the old pair, absorbing moisture and nutrients from the older leaves. The old leaves will gradually shrivel and dry out to a papery husk as the new leaves develop, and it is crucial to withhold water completely during this period. Watering too soon can disrupt this natural process, preventing the old leaves from being fully reabsorbed and causing improper development of the new pair.
As spring progresses and the old leaves completely dry, the new leaves are fully formed. This marks the beginning of their active growth phase in late spring and summer, when cautious, infrequent watering can resume only when the plant shows signs of thirst.
Many Lithops species typically flower in autumn, producing daisy-like yellow, white, or pale orange blooms that emerge from the fissure between the leaves. These flowers usually open in the afternoon on sunny days and close at night. After flowering, the plant enters a period of dormancy, often in mid-summer or winter, during which watering should be stopped.
Common Ass Plant (Lithops) Problems
Several common issues can arise when growing Lithops, often stemming from improper care, particularly watering.
Rot is the most frequent problem, almost always caused by overwatering, especially during dormancy or when old leaves are still present. Signs include mushy, yellow, or translucent leaves, brown spots, or splitting of the leaves. If rot is detected, watering should cease immediately, and the plant may need to be unpotted to check for root rot, removing any affected, mushy roots.
Wrinkling or shrinking of the leaves can indicate thirst if the plant is in its active growth phase and the soil is dry. However, if wrinkling occurs during winter or new leaf emergence, it is a normal part of the old leaves being reabsorbed and does not require watering. Severe shrinking coupled with a dry, crispy appearance can point to extreme underwatering or root damage.
Etiolation, or stretching, is a clear sign of insufficient light. This results in tall, weak growth and a loss of the plant’s characteristic compact, stone-like shape. Moving the plant to a brighter location with more direct sunlight is the solution, though etiolated growth is often irreversible.
A lack of new growth or activity can be concerning, but it often simply means the plant is in a dormant phase or is slowly developing new leaves inside. Patience and adherence to the natural growth cycle are important.