Pachycereus marginatus - Mexican Fencepost Cactus

Pachycereus marginatus, commonly known as the Mexican Fencepost Cactus, is native to central Mexico, where it grows in dry valleys and rocky slopes with well-drained soils. It thrives in areas with high sun exposure and infrequent rainfall, relying on its succulent stems to store water during drought.

This species forms tall, columnar stems that can reach up to 4–6 m in height, usually growing in close clusters that resemble fence posts. The stems are a uniform dark green with 5–7 prominent ribs, each lined with small, evenly spaced areoles bearing short, bristly spines. Its upright growth and neat symmetry make it a popular landscaping choice in warm, arid climates.

Flowering typically occurs in spring and summer, with small, tubular, pink to red blooms appearing along the stem ribs near the tops of mature columns. These are followed by red, fleshy fruits containing edible pulp and numerous seeds, which are eaten by birds and other wildlife.

Care Tips:

• Light: Requires full sun for healthy, upright growth.
• Water: Water deeply but infrequently in the growing season; keep almost dry in winter.
• Humidity: Prefers very low humidity.
• Media: Use a sharply draining cactus mix with coarse sand or gravel.
• Fertiliser: Apply a diluted low-nitrogen cactus fertiliser monthly during active growth.
• Temperature: Tolerates high heat; can withstand brief drops to around 0 °C if kept dry.
• Repotting: Repot rarely, only when needed, as the plant grows slowly in cultivation.