Plate No. 28

Blue Barrel

Ferocactus glaucescens

"A powdery blue globe with lemon-yellow spines"

Native to

Hidalgo and Querétaro, Mexico

Botanical illustration of Blue Barrel
Ferocactus glaucescens — drawn from life
History

A brief account

One of the most beautiful barrel cacti, wrapped in a fine blue bloom that rubs off under a fingertip. Its yellow crown-of-thorns flowers appear in early summer. Endemic to the limestone canyons of central Mexico.

How to care for

Blue Barrel (Ferocactus glaucescens) grows best when its natural cycle of strong light, freely draining soil and measured watering is respected. Give it full sun. Water it according to its seasonal needs: moderate in summer; dry in winter. Plant it in mineral cactus mix with limestone chips. A container with an unobstructed drainage hole is essential, because moisture lingering around cactus roots can quickly lead to rot. Keep its temperature needs in mind: 5–35°c. frost-tender. During active growth, check the compost before watering rather than following a rigid calendar, since heat, light and pot size all change how quickly it dries. Reduce watering during cool or dormant periods, keep the plant well ventilated, and wait until the growing medium is dry before watering again.

How to propagate

From seed; offsets are rare. Separate established offsets during the warmer growing season, using clean tools and preserving any roots already attached. Allow damaged surfaces to callus before potting into a dry, mineral-rich mix, then water cautiously while the new root system establishes. Young cacti are especially vulnerable to excess moisture. Use a small pot with excellent drainage, provide bright filtered light while roots establish, and move the new plant gradually into the light, temperature and watering conditions preferred by a mature Blue Barrel.
Cultivation

Quick tips for care & planting

Light
Full sun.
Water
Moderate in summer; dry in winter.
Soil
Mineral cactus mix with limestone chips.
Temperature
5–35°C. Frost-tender.
Propagation
From seed; offsets are rare.