Pachycereus pecten-aboriginum is a columnar cactus plant native to Mexico. They can grow up to 15 m high. The trunk of this species is 1.2 to 5.0 m tall. The specific name, pecten-aboriginum, is from the Latin, and means "native combs".
The cactus has a broad distribution along the Pacific coast of Northwestern México. It is one of the most massive columnar, treelike cacti in the world, often 7 to 15 m tall. The trunk is short but very large often branching within 0,5-3 m of the base with many massive branches. Pachycereus pecten-aboriginum blooms with white with reddish brown exterior, showy with purplish outer petals flowers that are 5 to 10 cm long, with a floral tube covered with dense brown velvety wool. Unlike other columnar cacti it may flower at any time, even though late winter and spring is the most common. The flowers are nocturnal, open in the evening and closing about midday.
These cacti like only a short winter's rest, and should be kept almost completely dry during the winter months. If the soil is allowed to be dry for too long, root loss could follow but equally the same result would occur if the plants were both wet and cold. From March onwards the plant will begin to grow, and watering should be increased gradually until late May, when the plant should be in full growth. Water regularly during the summer, so long as the plant pot is allowed to drain and not sit in a tray of water.
The plant needs full sun, avoiding only the harshest summer sun. If kept too dark, plants may become overly lush and green.
Feeding may not be necessary at all if the compost is fresh. Then feed in summer only if the plant hasn't been repotted recently.
During the summer it is best to keep the plants outside, where the temperature can rise to over 30°C with no harm to the plant. Grown specimens resist to -4°C for a short time, but it is best to keep above 0° C to avoid ugly spots on the plant's epidermis. Inside, normal room temperatures (65°F/18.3°C - 75°F/23.8°C) are suitable.
