Myrtillocactus geometrizans, also known as Blue Myrtle cactus (and a myriad of other names), is a columnular tree-like cactus native to Mexico. In nature, the cactus may reach 20 feet (4 m) in height, with the crown reaching up to 25 feet (5 m) in width. Individual joints reach up to 3 feet (1 m) in length. They have 5-8 ribs that are approximately 1 (2.5 cm) in depth with areoles about 1 inch (2.5 cm) apart. Each areole may have up to 5-9 spines, but generally they have 3-5 spines about 0.5 inches (1.2 cm) long. They are a slow growing cactus in containers, are very easy to grow and are hardy in USDA zones 9-11.
Blooming: In the greenhouse, this cactus blooms in late March with 1-1.5 inch (2.5-3.7 cm) greenish white flowers. There may be as many as 5-9 flowers per areole. The flowers are followed by 0.75 inch (2 cm) purplish fruits that are edible.
Culture: Myrtillocactus geometrizans need full sun with a well-drained soil mix. In the greenhouse, we use a soil mix consisting of equal parts of loam and sand with small gravel added to ensure drainage. The plants are well watered and allowed to dry out before watering again. We fertilize them only once during the growing season with a balanced fertilizer. During the winter months, water is restricted to only enough to keep the stems and branches from shriveling. We never let the nighttime temperatures fall below 55°F (13°C).
Propagation: Myrtillocactus geometrizans is propagated from cuttings and from seed when available. Cuttings must be kept very dry to root.
Myrtillocactus geometrizans was featured as Plant of the Week September 8-14, 2006.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.