Mexican Fencepost
Pachycereus marginatus
A columnar cactus traditionally used as a living fence, turning a dramatic purple when cold weather arrives.
Frost sensitive, hardy to about 28°F, USDA 9-11; a low-desert plant needing frost protection in cold pockets.
AMWUA Notes
Drought tolerant columnar cactus that forms a water-thrifty living fence.
Care Guide
Water established plants monthly in summer only and keep dry in winter; sharp drainage prevents rot.
Remove damaged columns; individual stems can be cut and re-rooted to extend the living fence.
Light spring feeding optional.
Generally trouble-free; watch for scale and mealybugs between the ribs.
Stems flush purple in cold weather; protect from hard frost below 28°F.
Soil, Feeding & Propagation
Gritty, fast-draining mineral soil or decomposed granite; low organic matter
Needs sharp, fast-draining soil.
Low feeder.
Stem cuttings re-rooted to extend the living fence
1-2 ft apart in a row for a fence; 5 ft as a clump
Shallow, non-invasive roots; nearly spineless columns are relatively path-safe
Placement Tips
- •Plant columns in a tight row for a living fence or screen.
- •Nearly spineless, so relatively safe near seating.
- •Give room for the 5 ft cluster.
- •Site in fast-draining soil.
Features
Best Uses
Companion Plants
Quick Stats
Design Styles
Include in Your Project
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Use this care guide to maintain your Mexican Fencepost. Questions about your landscape? Reach out anytime.
Data from 2024 AMWUA “Landscape Plants for the Arizona Desert” guide.