Containers with drain holes which allow excessive water to leave are vital for the health of Haworthias. The number and size of holes are less important as they don’t impact the volume of water drained. A container should make 30~50% room for the roots to elongate, otherwise, the plant growth may stunt. Some Haworthia species (for example, H. truncata) have deep roots and fit better in relatively deeper containers.
A container made of a porous material (for example, unglazed clay-based ceramics) is air permeable and evaporates a large amount of water through the sides. This causes the tip roots reaching the sides to be desiccated, and inhibits the root growth nearby. Unless growing in a cold or humid climate and rapid water evaporation is needed, containers made of non-porous materials (for example, plastic and glazed ceramics) are generally better.