Mexican Fence Post Cactus

Mexican fencepost cactus is a tall, dark-green columnar cactus with a clean architectural outline. It makes a dramatic accent in hot, dry landscapes and can also grow in a large, well-drained container. [Kew](https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:153112-2) accepts Marginatocereus marginatus; Cereus marginatus and Pachycereus marginatus are listed synonyms. ## Size and form The [University of Arizona Campus Arboretum](https://apps.cals.arizona.edu/arboretum/taxon.aspx?id=20) reports cultivated stems up to 4 meters and a landscape size of 11–15 feet high by 6–10 feet wide. Those ranges support the catalog’s existing metric points and labels. Stems have 5–7 ribs and may develop basal branches with age. ## Siting Provide full sun, heat and fast-draining soil. The [Arizona Municipal Water Users Association](https://www.amwua.org/plants/mexican-fencepost) gives this cactus very low water needs and cold tolerance of about 20°F. It flowers in spring, and its dark green stems remain evergreen. ## Maintenance Keep irrigation infrequent after establishment and avoid waterlogged soil. Protect it from freezing temperatures and handle spined stems carefully during planting or pruning.