Blue Myrtle Cactus

Blue myrtle cactus forms upright, blue-gray columns that can branch into a sculptural, candelabra-like outline with age. Small pale flowers may be followed by sweet, dark fruits, while the ribbed stems provide strong year-round structure in a warm, sunny, sharply drained site. ## Growing The [University of Arizona Campus Arboretum profile](https://apps.cals.arizona.edu/arboretum/taxon.aspx?id=991) describes a columnar to tree-like cactus with blue-gray ribbed stems, spring flowers, and edible fruit. Its garden specimen measurements are about 11–15 feet tall and 6–10 feet wide. The [RHS species profile](https://www.rhs.org.uk/plants/11310/myrtillocactus-geometrizans/details) describes the Mexican species’ ribbed, bluish-green stems and pale summer flowers; its blue-green ribs remain decorative even when the cactus is not flowering. Grow in full sun, with light shade for young plants in very hot conditions, and use a mineral, well-drained soil. This cactus is suited to a large container, dry garden, or protected warm-climate landscape. ## Seasonal Interest Older plants carry small pale flowers, then fleshy red-to-blue fruits. The distinctive stem color and branching form remain the main feature when the plant is not flowering. ## Maintenance Water deeply in warm weather, then allow the soil to dry before watering again. Reduce water in cool weather and protect from frost. Use a stable, fast-draining container mix and handle the spiny stems carefully when repotting.