Ferocactus glaucescens aka Blue Barrel

Ferocactus glaucescens is known as the glaucous barrel cactus. This evergreen succulent belongs to the cactus family, Cactaceae. It comes from eastern and central parts of Mexico. Its range includes Guanajuato, Hidalgo, Querétaro, and San Luis Potosí. It grows in dry woods and dry scrub. Plants also grow among limestone rocks and on hills. Some sites have rocky ground with juniper trees. The species has a Least Concern listing from 2017. Land use changes still cause losses in some local groups.

A plant may have one stem or form a clump. New heads grow near the base as it ages. Older clumps can build up into a broad mound. The grey-green stem starts round, with a sunken top. With age, it takes on a short column shape. Garden size reaches about 1.6 feet [0.5 metres] tall and wide. Stem height reports range from 1.5 to 2 feet [0.45–0.6 metres]. Each stem has 11 to 15 ribs. Groups of six or seven straight, pale yellow spines line them. Some groups also have one central spine.

The yellow flowers have a funnel shape and finely fringed edges. They measure about 0.10–0.13 feet [0.03–0.04 metres] across. LLIFLE places flowering in late spring and summer. Chicago Botanic Garden records blooms from July to August. Flowers last well, and bees pollinate them. Plants can bloom before they reach their full size. The small, fleshy fruits may be white or yellowish. Some have a red tinge and retain old flower parts.

This cactus suits pots, patios, and use as a specimen. RHS gives a maturity time of ten to twenty years. Outdoor listings allow full sun or some shade. Under glass, RHS calls for bright light filtered through cover. Use cactus compost, keep air humidity low, and ensure good drainage. Suitable soils include sand and loam across a broad pH range. Water moderately during growth, but keep it nearly dry in winter. Feed during growth every two or three weeks. Chicago lists USDA zones 9–11; RHS rates it H2. The RHS rating means it cannot survive freezing.

The plant needs no pruning, and RHS reports few disease problems. Mealybugs may attack it. Sow seed in early spring to raise new plants. People eat the fruit raw and sometimes collect wild plants for food. Useful Tropical Plants also reports emergency fluid use from crushed stem pulp. That fluid has a poor taste and a slimy feel. The same source lists no known hazards or medicinal uses. Its broader claims about genus-wide food uses do not establish uses for this species.