– Pilosocereus purpureus (2017)

By Betty Gravlin (May 2017)

Pilosocereus is a genus of cacti distributed throughout Mexico, the Caribbean and Brazil. They are upright with relatively thin stems. In cultivation, they mostly are grown in greenhouses because of their size and need for warmth in the winter.

The Pilosocereus name derives from the Latin for “hairy cereus,” because of their spiny aureoles. Their flowers are shaped like tubes and often blue, and they grow fleshy fruits. Some species grow to a height of up to 30 feet.

The Pilosocereus purpureus cactus that I have is a single green column. It has 11 parallel lateral ribs that superficially resemble cephaliums, copious development of wooly, beard-like hairs in the flowering zone and bristles at the tops of the ribs. The column tapers at the top. It has brown and golden spines.

Growing Conditions

Light: Like most cacti, they need lots of direct sunlight to flourish.
Water: Watering them weekly should be sufficient, although they need a solid supply of water during the summer. Make sure not to overwater them, which can cause rot.
Temperature: Warm tropical temperatures, ideally around and above 70 degrees.
Soil: Pilosocereus plants like a dry soil with some organic material, and good drainage is absolutely essential.
Fertilizer: Complementing their water with a diluted liquid fertilizer once every few weeks during the growing season will help. Use a balanced fertilizer like a 20-20-20 with equal parts nitrogen, phosphorus and potassium.

Propagation

The best way to propagate Pilosocereus plants is by cuttings. You can cut off the top of the plant once it’s begun to mature and replant it as the bottom of a new one. This is a good way to produce new plants. Once the top cuts have rooted, they should flower fairly early in their lives, so cutting off the tops of existing plants is a good way to ensure flowering in your cacti.

Repotting

These are treelike, free-standing cacti that are usually too big to be grown in pots. Cacti in containers do benefit from sporadic repotting, though. Lift the plant gently (making sure to protect your hands), knock away old soil and replace in a larger pot. Make sure not to water the plant for a few weeks while it gets settled in its new container. Keep an eye out for pests like mealy bugs and red spider mites. Water regularly for best results.

Sources
CactiGuide.com – Pilosocereus puppureus Care – http://cactiguide.com/forum/viewtopic.php?f=25&t=38450
Tips for Growing Pilosocereus Cacti – https://www.thespruce.com/grow-pilosocereus-cacti-1902966