Botanical Name — Stenocereus beneckei
Plant Family — Cactaceae
Stenocereus beneckei are hardy, shrub-like cacti native to central Mexico, where they grow on sunny slopes and cliffs. Known for their striking gray-green coloration and sharp brown spines, as well as their obtuse ribs, these cacti act as a strong contrast to other cacti in a collection. The silver surface of this plant is a dense layer of waxy crystals called farina. It acts as a water repeller and sun reflector. A natural cleanser, the farina keeps dirt, pests, and pathogens from breaking the surface, so when rainwater strikes the plant, the unwanted debris easily binds with the droplets and falls from the cactus.
- Stenocereus beneckei require plenty of full sun. Eight hours of direct sunlight a day is ideal but at a minimum these plants should be provided with at least five hours.
- If you are growing them indoors, a spot in a south facing window is ideal. If growing these outdoors, place them in an area where they will receive dappled sunlight to protect them from peak afternoon sun.
- These cacti thrive in warm temperatures and low humidity. They will thrive in temperatures above 70 ºF.
- They are cold intolerant. It is advisable to bring them indoors once night time temperatures consistently fall below 50 ºF.
- Stenocereus beneckei are extremely drought tolerant. Always allow the soil to dry out completely in between waterings. When watering, water thoroughly, fully saturating the soil.
- If you are unsure whether or not the soil is dry, wait a few days before watering. It is much better to underwater than overwater. Excessive moisture can quickly lead to root rot.
- These plants prefer a gritty, sharply draining mix. Use cactus soil or amend regular potting mix with sand and fine pumice up to 50% to improve texture and drainage.
- In desert climates, these plants can be potted directly in the earth and grown outdoors year round.
- Large funnelform flowers, black-green with yellow blossoms, bloom atop the cactus in late spring to early summer, opening at night and lasting no more than 24 hours.
- Stenocereus beneckei do not require fertilization, however a boost of nutrients during the growing season will help them thrive. Use a fertilizer formulated specifically for cacti and succulents, once a month, during the spring and summer only.
- These plants can be reliably propagated from stem cuttings. Use a clean, sharp blade to sever a segment of a stem or an entire branch. Place the cutting in a shaded area for a few days to allow the wound to callous over, then pot in a well-drained cactus mix.
- These plants can also be grown from seed. Sow seeds just below the surface, using a well-drained soil mix. Provide a humid microclimate to encourage germination and keep soil evenly moist during the first few months to encourage seedling growth.
- These cacti are not especially prone to pests and diseases. Root rot can easily occur if the plant is overwatered. Keep an eye out for common pests such as mealybugs, aphids and scale.
Maintenance (pruning, legginess, repotting)
- Always wear gloves when handling this plant. The farina bloom on its surface is a protective layer and can easily be rubbed off on accident. It will not regenerate once gone.
- These hardy plants require very little maintenance. Container grown cacti prefer to be rootbound, so repotting should be necessary only once every two years. Repot into a planter 2” larger in diameter to give the plant plenty of room to continue growing.
- Stenocereus beneckei have no known toxicity to humans or animals. Spines are sharp so it is advisable to keep out of reach of pets and small children.