The Blue Torch Cactus – Care and Propagation Guide

Blue torch cactus, also known as Pilosocereus pachycladus is a columnar tree-like cactus with stunning bluish stems lined with ribs and golden spikes. It is a tall plant that can reach 30ft in its native habitat. However, its aesthetic beauty makes it a great addition to any landscape or garden.

Just like the Peruvian apple cactus, you won’t struggle to care for the blue care torch cactus in the right climate. Simply provide bright sunlight, great soil drainage, and infrequent watering. Bring it indoors when temperatures drop below 50°F (10°C), as hard frost may kill the cactus.

 In summary, here is what you need to know about this plant.

Names	Pilosocereus pachycladus (botanical), Blue Columnar Cactus, Tree cactus, and Blue Cactus.
Plant size	Neatly grows up to about 30ft in the wild and 6-12ft indoors. The branching can reach 2-4 ft. wide.
Temperature	It prefers 68°F to 86°F (20°C and 30°C). Temperature below 50°F may kill the plant.
Soil	Neutral to acidic loose and well-draining and moderately fertile soil.
Growth	Approximately 2 to 3ft per year. Slower growth rate indoors.
Humidity	Adapted to low humidity conditions.
Light	Full sun or bright indoor light (natural or artificial)
Propagation	Preferably through stem cuttings, seed germination, or offsets.
Blooming	Mature plants produce showy white bloom in summer.
Cold Hardiness	Zones 9-11 (USDA) – Not hardy to frost

Blue torch cactus care

The Blue torch cactus is native to the semi-tropical region of Brazil and some parts of Mexico. It is well-adapted to warm desert-like climates and your best bet is to grow it indoors if you come from the northern hemisphere or where temperatures keep fluctuating.

Here is what you’ll need to provide in terms of care.

1. Bright direct light

A mature Pilosocereus pachycladus prefers full sun to flourish. The cactus blue skin becomes more vibrant when it receives direct sunlight. Inadequate light makes the cactus grow leggy and paler green. Be sure to grow it on a sunny windowsill or under grow lights.

However, young or tender cactus plants from the greenhouse can be susceptible to sunburn if not properly acclimatized. It may take time to detect cactus sunburn, but common signs include brown or white patches on the stems. Be sure to move the affected plant to a shadier location.

2. Well-draining soil

Soil drainage is arguably the most important factor when growing cactus. You’ll need to grow your blue torch cactus in loose, well-draining soil that is moderately fertile. 75% of the soil must be a mineral grit such as perlite, pumice, or coarse sand. Preferably use soil mix for succulents and cacti.

3. Infrequent watering

Like other desert cacti, the Blue torch cactus is not a thirsty plant. You should infrequently water, most importantly when the top inch of the soil feels dry. Watering excessively before the soil is completely dry may cause root rot, a condition also common in plants grown in poorly drained soil.

While overwatering can be a problem, underwatering the cactus can also be an issue. Mainly, it causes the plant to become dehydrated and even die. Wilting is a common sign for underwatered cactus. Be sure to water the plant regularly as needed but not excessively.

4. Warm temperature

Pilosocereus pachycladus are desert plants well-adapted to heat conditions. They prefer consistently warm temperatures between 68°F to 86°F (20°C and 30°C). Prolonged exposure to temperatures outside this range may damage or kill the cactus. The plant should be protected from frost or freezing temperatures.

5. Low humidity

Blue torch cactus is well-adapted to low humidity levels common in arid and semi-arid regions. Generally, a humidity range of 40% to 60% is recommended for this plant. Excessively high humidity or moisture around the cactus can increase the risk of fungal diseases and rot.

Pilosocereus pachycladus propagation

Blue torch cactus can be propagated through several methods, including seed germination, stem cuttings, and offsets.

Stem cuttings method

Stem cutting is a common method for propagating the blue torch cactus. The cuttings are taken from healthy, mature stems and allowed to callus over for several days before planting in a well-draining potting mix. The cutting is then kept in a warm, bright location until it develops roots and new growth.

Seed germination

Seed germination can also be used to propagate Pilosocereus pachycladus. Seeds are obtained from a ripe fruit, dried and sown in a well-draining potting mix, and kept moist until they germinate. It is important to provide warm temperatures and bright, indirect light during germination.

Using offsets

Offsets, or “pups,” are small, new plants that develop at the base of the parent plant. These can be carefully separated from the parent plant and transplanted into their own pots. They will also need bright indirect sunlight and warm temperature to develop roots and several sets of true leaves.

Note: Whatever method is used to propagate a cactus, the soil must be kept gently moist and not wet. Misting should be done only when the top layer of the soil feels dry.

Potential problems in growing the Blue torch cactus

Pilosocereus pachycladus can be susceptible to pests and fungal or bacterial infections, especially if the plant is grown in poor conditions. Insect pests such as mealybugs, spider mites, and scale insects are known to cause infections and damage to the cactus as they suck sap from the plant.

If the plant begins to show abnormal signs such as webbing, and brown, white, or black spots on the stems, then treat it with a recommended insecticide. You may remove visible insects using a cotton swab dipped in isopropyl alcohol or spraying the cactus with a neem oil solution.

High levels of humidity, excess watering, and poor ventilation trigger fungal infections. Removing a diseased section of the plant may also stop the infection from spreading. Plants severely damaged by pests or infections should also be isolated or destroyed completely.

Final Thought

The blue torch cactus is an easy-to-care-for plant. To keep your plant healthy, provide appropriate growing conditions, including proper ventilation, bright light, well-draining soil, and balanced watering. Be sure to monitor your plants regularly for signs of infection or infestation and provide appropriate treatment.

References

• “Growing Indoor Plants with Success,” University of Georgia Extension
• “Care of Non-Hardy Cacti & Succulents,” Cornell Cooperative Extension
• “Guide to Common Cactus and Succulents of Tucson,” Tucson Cactus and Succulent Society