Succulents are plants adapted to arid conditions, possessing specialized tissues to store water, which allows them to survive extended periods of drought. Gardeners often combine different varieties into single arrangements. However, mixing these species can be problematic, as their specific environmental requirements are not interchangeable. Their distinct native habitats demand radically different care schedules, creating incompatibilities that frequently result in plant failure.
Divergent Watering Requirements
The most common reason succulents should not be planted together involves their conflicting needs for moisture. Some succulents are extremely drought-adapted, while others require more frequent watering during their active growing season. Placing these two types in the same container guarantees that one plant will suffer from improper hydration.
For instance, species like Lithops, often called living stones, are adapted to periods of seasonal rainfall and require a long, completely dry dormancy period, sometimes needing water only three or four times per year. Watering them outside of their specific cycle, especially when they are “splitting” new leaves, causes them to rupture or rot almost immediately. Combining a Lithops with a softer succulent, such as an Aeonium or a Kalanchoe, forces a contradiction.
These softer-bodied succulents generally require more consistent moisture, often needing thorough watering every few weeks during warm months. If the arrangement is watered frequently enough for the Aeonium, the Lithops will quickly absorb excess moisture and succumb to root rot. Conversely, if the arrangement is kept dry enough to sustain the Lithops, the Aeonium will shrivel and perish from dehydration. This fundamental conflict makes them incompatible planting partners.
Mismatched Light and Temperature Tolerances
A second major source of incompatibility is the difference in light intensity and temperature tolerance between various genera. Succulents are broadly categorized by their light needs, ranging from those that crave intense, direct sun to those that prefer filtered light.
For example, many Echeveria and Crassula species originate from high-altitude deserts and require six or more hours of direct, unfiltered sunlight daily to maintain compact growth and vibrant coloring. Without this intense light, they will stretch and become pale in a process known as etiolation.
In contrast, genera like Haworthia and Gasteria evolved to grow under the cover of shrubs or rocks in their native South African habitats. Their leaves often feature translucent “windows” that allow light to penetrate to the inner tissues, an adaptation for low-light conditions. When these shade-preferring plants are exposed to the full sun required by Echeveria, their leaves will often scorch, turning brown or white from sun damage.
Temperature requirements also create planting conflicts, especially in outdoor arrangements. Pairing a cold-hardy species, such as Sempervivum (Hens and Chicks), which can survive temperatures down to USDA Zone 3, with a tropical succulent is problematic. Many Euphorbia varieties are sensitive to frost and require protection below 35°F, making it impossible for both plants to survive a cold winter together.
Growth Habits and Root Competition
The physical growth patterns of different succulents can also lead to incompatibility, particularly in confined spaces like containers. Some plants exhibit aggressive, fast-spreading habits, while others are slow-growing and solitary, making them poor companions. Creeping varieties of Sedum, for example, spread quickly and root easily along their stems, forming dense mats that function as ground cover.
When a fast-spreading Sedum is planted next to a slow-growing, solitary rosette like an Echeveria or a small Cactus, the aggressive plant quickly dominates. The Sedum will monopolize the soil surface, outcompeting the slower plant for water and nutrients. Furthermore, a tall, clumping succulent can cast a shadow on a shorter neighbor, creating a localized light conflict that starves the shaded plant. This smothering effect is a common cause of failure in mixed arrangements.
How to Ensure Planting Compatibility
To create a successful mixed succulent arrangement, always group plants that share the same ecological requirements. Start by categorizing potential partners by their native origin, as plants from the same desert region often have similar needs. Confirm that all selected plants belong to the same hardiness zone and have identical minimum temperature tolerances. The most important factor to verify is the watering schedule and seasonality, ensuring that none have conflicting dormancy periods. Assess the mature size and growth rate of each plant, avoiding the combination of rapid spreaders with delicate specimens. If a desired plant has unique needs, such as a Lithops, it is best housed alone in a dedicated container.