Pachycereus pringlei aka Cardon Cactus

Pachycereus pringlei is a tree-like cactus from northwest Mexico. Gardeners know it as elephant cactus or Mexican giant cardon. Its range includes Sonora and both states of Baja California. It grows in deserts, dry scrub, and some dry forests. Plants may stand alone or form large groups. Sheltered canyons support large plants; exposed coasts support smaller ones.

Large plants reach about 33–39 feet [10–12 metres]. Garden specimens may exceed 39 feet [12 metres], according to RHS. Their spread reaches about 8–13 feet [2.5–4 metres]. Reports of exceptional plants reach 70 feet [21 metres]. A thick trunk supports many tall, upright branches. Some plants live for more than 200 years. The stems range from blue-green to deep green. Deep ribs run along them and flatten with age. Spine clusters line the ribs, but old stems may lose them. The thick green skin becomes brown or grey bark. Older bark may crack as the trunk grows thicker.

Mature plants bear white flowers near the branch tips. Flowers open at night during spring and early summer. Chicago Botanic Garden lists bloom from March through June. Sources give flower widths of roughly two to three inches. Each bloom lasts less than a day. Outer petals may have green or red tones. Round, red fruit follows, with short tan spines outside. The flesh inside is bright red and edible. People eat it fresh or cooked, and make jelly. They also grind dried or roasted seeds into flour.

Give this cactus full sun and soil that drains well. Young plants benefit from some shade. RHS accepts sandy or loamy soil across a broad pH range. Under glass, use peat-free, loam-based compost with extra grit. Water in moderation during growth, then stop during dormancy. Feed two or three times during the growing season. Chicago lists USDA zones 10–12; RHS gives UK rating H1B. Young plants cannot withstand freezing temperatures. Older plants may survive brief frosts down to about 25°F. RHS gives a maturity period of 20–50 years.

Its tall form suits specimen planting in dry landscapes. People also grow it as a barrier hedge. Dried stems serve as building material and fuel. Local traditions use the stems for wounds and other ailments. These reports describe use, not proof of medical benefit. Useful Tropical Plants reports no known hazards. RHS reports few disease problems, but mealybugs and scale may attack. Plants need no pruning. Seeds and summer stem-tip cuttings provide ways to grow new plants.