Myrtillocactus Geometrizans (mir-til-oh-KAK-tus, jee-oh-MET-rih-zans) cactus is a member of the Cactaceae family known for its striking blue-green stems.
The species is also known by the scientific names of:
- Cereus Geometrizans
- Myrtillocactus Grandiareolatus
- Myrtillocactus Geometrizans (Mart. Ex Pfeiff.)
- Blue Candle Cactus Care
- How to Propagate Myrtillocactus Geometrizans
- Myrtillocactus Geometrizans Pest or Diseases
- Blue Myrtillocactus Uses and Recommendations
Blue myrtle-cactus is a member of the family Cactaceae and the best-known species of the genus Myrtillocactus. Myrtillocactus geometrizans is native to northern and central Mexico down to Oaxaca, where it is widespread in tropical deciduous forests and xerophilous scrub. It is also prevalent in the Chihuahuan desert.
Myrtillocactus comes from the Greek word myrtillus, which means small myrtle and cactus.
Geometrizans, on the other hand, refers to the geometric markings (formal pattern) on the plant.
Due to its blue-green color and growth habit, the plant has acquired several common names. The most popular and widely used nicknames are:
- Blue candle
- Blue myrtle cactus
- Whortleberry cactus
- Bilberry cactus
- Blue boy cactus
- Blue candle crested cactus – variant
- Crested blue candle cactus – variant
Other Popular Columnar Succulents include:
Blue Candle Cactus Care
Size and Growth
Myrtillocactus is a fast-growing columnar succulent tree cactus that grows up to 13’ to 16’ feet tall.
Featuring 2” to 4” inch thick blue-green or blue-grey glaucous stems with multiple areoles and 5 to 8 ribs, the plant remains unbranched for a long time, but produces several branches upon maturity, resembling candelabra.
Hence, the common name, blue candle.
The stems are succulent and have small central spines growing from the areoles.
Upon maturity, the plant displays a dense growth of stems, which are highly branched and closely growing.
In its natural habitat, the crown of the plant can spread up to 8’ to 12’ feet in width.
Crested Blue Candle Cactus: A Connoisseur Variant
The crested blue myrtle cactus, or crested blue candle cactus, is a variant or mutated form of Myrtillocactus Geometrizans.
The plant has a unique crested fan-like shape instead of its typical columnar growth. This unusual and rare variation, characterized by its wavy growth, is a favorite in the cactus and succulent community.
Flowering and Fragrance
The columnar candelabra cactus produces small creamy or greenish-white flowers in spring after it has grown to about 2’ feet in height.
While the blue candle cactus flower color is initially white, it later changes to a dark red bloom.
The showy greenish-white flowers of Myrtillocactus geometrizans are fragrant and attract pollinators.
Flowering is followed by the production of small dark purple berry-like oblong fruits, which resemble the fruit of Vaccinium myrtillus, called whortleberry or bilberry.
Myrtillocactus geometrizans’ common names, whortleberry cactus, and bilberry cactus, are based on this resemblance.
The fruit, known as garambullo, has a sweet flavor and is edible.
Light and Temperature
Like all other cacti and succulents, the blue myrtle cactus needs sunlight to grow properly.
However, do not expose the young plants to direct full sun; keep them in light shade or partial shade until they reach maturity and then shift to a sunny full sun location.
The plant is only semi-hardy and can only tolerate temperatures down to 25° degrees Fahrenheit (-4° C).
Protect your Myrtillocactus geometrizans cactus plants from extremely cold weather and frost or they may die.
Due to its poor winter hardiness, do not expose the plant to nighttime temperatures below 50° degrees Fahrenheit (10° C) to ensure proper growth.
In the United States, blue myrtle is hardy to USDA zones 9a to 11b.
Blue Myrtle Cactus Care: Watering and Feeding
This shrubby cactus species is fairly drought-resistant but appreciates watering in summer. However, it cannot tolerate standing water.
Good advice for watering whortleberry cactus is to water thoroughly once and then let the soil dry out before watering again. Also, avoid overhead watering.
Reduce the watering to only a bare minimum in winter to prevent the soil from being cold and wet for extended periods of time, as it can lead to root loss.
For best growth, feed your blue myrtle with a specialized cactus fertilizer once a month during the spring and summer seasons.
Soil and Transplanting
Bilberry cactus needs a well-draining soil mix as it cannot tolerate wet or waterlogged soil.
Adding some gravel to the soil can help improve its drainage.
Since this cactus species display a fast growth rate and grow to form big, dense shrubs, they need plenty of space to grow and are likely to need repotting almost every other year.
Grooming and Maintenance
While this candelabra-like cactus species is easy to grow and doesn’t need pruning or too much care, once established, you must be careful about light exposure and water to ensure the best growth.
The plant must also be protected from extremely cold weather to stay alive.
How to Propagate Myrtillocactus Geometrizans
Blue myrtle cactus are either grown from seeds or multiplied through stem cuttings in summer.
Collect seeds from ripe fruits, clean and dry them and then sow directly into the ground after the end of the frost season.
When propagating from cuttings, let their cut surfaces dry out (callous) for 2 to 3 weeks before planting them into the soil.
Water once and then let the soil dry out before watering again.
Cuttings only root in warm/hot weather.
Myrtillocactus Geometrizans Pest or Diseases
While myrtillocactus geometrizans care isn’t susceptible to many diseases and pests, it can cause fungal diseases like root rot if left in damp and poorly drained soils for extended periods of time.
Blue myrtle is attractive to birds, butterflies, bees, and moths.
Blue Myrtillocactus Uses and Recommendations
The columnar cactus Myrtillocactus with its dense growth of thick stems, is a popular cactus species for cultivation.
It is widely used as grafting stock for cacti plants and for adding visual interest to landscapes.
The fruits of the plant are widely consumed in Mexico, where it is also grown for commercial purposes.
Several crested clones of Myrtillocactus geometrizans are also available.