Echinocactus platyacanthus (Giant Barrel Cactus)

Scientific Name

Echinocactus platyacanthus Link & Otto

Common Names

Giant Barrel Cactus, Giant Viznaga, Large Barrel Cactus

Synonyms

Copiapoa macracanth, Echinocactus arachnoideus, Echinocactus aulacogonus, Echinocactus edulis, Echinocactus ghiesbreghtianus, Echinocactus grandis, Echinocactus helophorus, Echinocactus ingens, Echinocactus irroratus, Echinocactus karwinskii, Echinocactus macracanthus, Echinocactus minax, Echinocactus oligacanthus, Echinocactus platyceras, Echinocactus saltillensis, Echinocactus tuberculatus, Echinocactus viznaga, Echinofossulocactus helophorus, Echinofossulocactus karwinskianus, Echinofossulocactus macracanthus, Echinofossulocactus platyceras, Melocactus ingens, Melocactus platyacanthus, Melocactus tuberculatus

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Cacteae
Genus: Echinocactus

Description

Echinocactus platyacanthus is a slow-growing cactus up to 8.2 feet (2.5 m) tall and up to 5 feet (1.5 m) wide. The stem is grayish-blue and the straight, rigid spines are black. The apex of the cactus is flat and covered with a yellow felt-like substance. It is heavily ribbed and has large areoles. The flowers are diurnal, tubular, vivid yellow, up to 2.8 inches (7 cm) in diameter and appear at the end of spring and summer. The fruits are yellowish, 1.2 inches (3 cm) long and up to 1 inch (2.5 cm) in diameter. This cactus can live over 100 years.

Photo via wikimedia.org

Hardiness

USDA hardiness zones 9b to 11b: from 25 °F (−3.9 °C) to 50 °F (+10 °C).

How to Grow and Care

Overall, these are very attractive cacti for dish gardens or indoor display. A collection of them is especially attractive, as they look like a collection of balls tossed upon the ground. It is critical, however, to never let these cacti be exposed to prolonged periods in water, or even very high humidity. They will suffer from rot in the presence of humidity. Echinocactus are vulnerable to pests including aphids, mealybugs, scale, and white fly. If possible, identify the infestation as early as possible and treat with the leave toxic option.

It is best to repot in the beginning of the growing season, or summer. To repot a cactus, make sure the soil is dry before repotting, then gently remove the pot. Knock away the old soil from the roots, making sure to remove any rotted or dead roots in the process.

Learn more at How to Grow and Care for Echinocactus.