Columnar cactus

Mexican fence post cactus

Pachycereus marginatus

Columnar cactus with straight dark green stems 3–6 m tall, clumping from the base; Gardmi uses a 1 m clump. Hardy to about −4 °C briefly (USDA 9b). Used as a living fence in Mexico.

Use in planner

Planning parameters

Use these values as a practical planning envelope: they describe the adult plant, not the young seedling.

Adult height: 3-6 m
Crown diameter: 1 m
Root zone: 1 m
Root type: Shallow spreading roots; stems branch from the base into a clump
Recommended setback: About 0.5 m from walls and paths
Growth rate: Medium
Hardiness: USDA 9b–11 (about −4 °C for short periods)
Crown density: Sparse

Site requirements

These conditions decide whether the plant will establish well after planting.

Light: Full sun
Watering: Very low
Soil type: Gritty, very well-drained soil
Drainage: Rots in wet or poorly drained soil
Soil pH: Neutral to alkaline

Root system and placement

Plan a root zone of about 1 m diameter

Garden role and season

These fields help choose the plant by composition, privacy, flowering and year-round value.

Form: Straight upright columns in a clump
Foliage: Dark green ribbed stems with white felted areoles and short spines
Season: Year-round
Bloom: Small pink-red flowers along the ribs in spring
Fruit: Small spiny fruits
Garden use: Living screens, dry gardens, courtyards and modern xeriscape accents

Care and risks

This is the practical part for future maintenance and safe placement on the plot.

Maintenance: Water rarely; keep dry in cool weather
Pruning: No pruning; cut stems only to shape or propagate
Risks: Short spines; tall stems can topple in wet soil or strong wind