Botanical Name — Myrtillocactus geometrizans
Common Name — Blue Myrtle-Cactus
Plant Family — Cactaceae
Native to Central and Northern Mexico, the Mytillocactus geometrizans prefers dry, hot conditions with plenty of direct sun. It’s known for its brilliant blue-green color and branching, candelabra structure. Its blue coloration will become more saturated with the proper sunlight. Avoid touching the plant's tissue with your bare hands as you may leave behind an oily fingerprint.
These cacti prefer lots of sun, at least five hours of direct sun daily. Young plants may need shade protection from afternoon sun.
Indoors a south facing window is ideal. Outdoors seat them in a place where they will get plenty of sun exposure, but protect them from intense, peak afternoon sun.
These plants are semi- hardy. Prefers a cool or warm climate where temperatures remain between 60 F to 80 F. Best to bring indoors when the temperature falls below 50 F.
Keeping it in a cooler environment in the dormant months may encourage blooms come spring.
Myrtillocactus prefers to stay on the dry side. In the summer water them only when the soil has dried out entirely. Always err on the side of underwatering. They are built to withstand drought, and overwatering is one of the quickest ways to kill them.
During the winter, water very infrequently if at all. It’s safe to cut back on watering entirely. Water should be restricted to only enough to keep the stems and branches from shrivelling.
They prefer a gritty, sharply draining mix. A cactus mix would work fine. You can amend it with sand or fine pumice up to 50% to improve grittiness and drainage.
In the optimal summer conditions, small cream colored flowers can appear across the top of the cacti’s body, succeeded by a tiny very sweet, edible, plum-like fruit.
You can fertilize during the spring and summer months to give them a boost or refresh their soil. Apply a balanced cactus fertilizer diluted at half strength, once a month.
Propagation can be done by cuttings in summer. Let cutting callus before planting. Make sure that it is kept warm and dry to root.
Myrtillocactus are not especially susceptible to pests or diseases. Keep an eye out for common pests such as aphids, mealy bugs, and scale.
Root rot can be a common issue if overwatered.
Maintenance (pruning, legginess, repotting)
These plants are very low maintenance. They prefer to be rootbound. Repot them once every one to two years. Early spring is the best time to repot, when they are just waking from their dormancy.
Myrtillocactus are not known to be toxic to humans or pets.