The genus Echinocactus (Barrel Cactus) includes about six species of barrel cacti native to Mexico and the southeastern United States. These are true desert plants that cannot handle any humidity or standing water to grow. The most common among these plants are almost perfectly round when young, so, therefore, make excellent display plants. They are also highly attractive with their rows of spines of their deeply ribbed lobes.
As they grow, it is not uncommon for them to stretch out, so they look more like ovals than circles. As with most cacti, the secret to their successful growth indoors is nearly perfect drainage, as opposed to letting them dry out.
Light: Full sun. Barrel Cactus do best in a very sunny window, perhaps a southern exposure. Plants that do not get enough sunlight will grow more slowly and fail to thrive.
Water: Water infrequently and ensure that the soil drains completely. Do not leave any water sitting in the tray or allow them to sit in water. They are very prone to root rot.
Soil: A cactus soil mix is ideal. If you use a regular peat-based mix, be sure to add sand or extra perlite to enhance drainage and repot the plant when the soil begins to break down.
Fertilizer: Feed with a weak liquid cactus fertilizer throughout the growing season.
Barrel Cactus are typically propagated by seed. Mature cactus will bloom in the summer with flowers that grow in whorls around the plant's top.
To seed a cactus, plant the seeds shallowly in a cactus mix and keep them warm and slightly moist.
It's best to repot at 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. Treat any cuts with a fungicide. Place the plant in its new pot and backfill with potting soil, spreading the roots out as you repot. Leave the plant dry for a week or so, then begin to water lightly to reduce the risk of root rot.
Overall, these are beautiful 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. However, it is critical never to let these cactus be exposed to prolonged periods in water or even very high humidity. They will suffer from rot in the presence of moisture. Echinocactus are vulnerable to pests, including aphids, mealy bugs, scale, and whitefly. If possible, identify the infestation as early as possible and treat with the leave toxic option.