From a plant's perspective, the single most critical factor in a pot is its ability to prevent root rot. My roots are highly susceptible to sitting in waterlogged soil. Therefore, the pot must have multiple, large drainage holes at the bottom. This is non-negotiable. A pot without excellent drainage is a death sentence, as it will trap moisture around my root ball, leading to fungal infections and rot that I cannot recover from. The material of the pot plays a key role here. Unglazed terracotta or clay pots are ideal because they are porous, allowing both water and air to pass through their walls. This helps the soil mix dry out more evenly and quickly, mimicking my preferred arid conditions.
Choosing the right pot size is about finding a balance between providing room for growth and avoiding excess soil. A pot that is too large is a significant threat. An oversized pot holds a greater volume of soil, which in turn retains more water for a longer period. My root system is relatively small and slow-growing; it cannot absorb all that moisture quickly enough. This creates a perpetually damp environment that is completely alien and dangerous to me, encouraging the root rot I fear. Conversely, a pot that is too small will constrict my roots, severely stunting my growth and caudex (swollen trunk) development. The perfect pot is only 1-2 inches (2.5-5 cm) larger in diameter than the root ball of my current container. This provides just enough space for a year or two of growth without creating a dangerous reservoir of wet soil.
My growth habit involves developing a wide, bulbous caudex at my base and a root system that tends to spread out laterally rather than digging extremely deep. Therefore, a pot that is wider than it is deep (often called a "bonsai pot" or azalea pot) is often the most suitable shape. This shallow profile provides ample room for my caudex to expand and my surface roots to spread, while minimizing the depth of soil below that could stay dangerously wet. As mentioned, unglazed terracotta is the superior material due to its breathability. While plastic or glazed ceramic pots can be used if they have exceptional drainage, they require a much more careful watering hand and a very gritty soil mix to compensate for their non-porous nature.
The pot choice cannot be separated from the soil medium you provide. Even in a perfect terracotta pot, a dense, moisture-retentive potting mix will still lead to problems. My roots require a sharply draining, gritty, and airy substrate. A mix specifically designed for cacti and succulents, amended with extra perlite, pumice, or coarse sand (50-70% inorganic material), is essential. The pot and soil must work together as a system. The pot's drainage holes and porous walls allow excess water to escape, while the gritty soil ensures that water flows through quickly and does not become compacted, providing the perfect balance of moisture, nutrients, and oxygen to my roots.
