Parodia crassigibba aka Green Tomato Cactus

Parodia crassigibba is a small cactus from southern Brazil. Its native range includes Rio Grande do Sul. It belongs to the cactus family, Cactaceae. Kew describes it as a succulent subshrub from a subtropical climate. Gardeners may also find it named Notocactus crassigibbus. The RHS uses the common name ball cactus. Its rounded shape and summer flowers suit container displays.

The plant has a dark green stem with 10–16 ribs. Thin, curved radial spines grow along these ribs. The RHS describes a rounded plant reaching 0.66 feet [0.2 metres]. Its broader height range is 0.33–1.64 feet [0.1–0.5 metres]. The listed spread reaches 0.33 feet [0.1 metres]. These figures differ within the same profile. The plant may form clumps as it ages. The RHS gives five to ten years to reach maturity. It also classes the plant as evergreen.

Flowers appear at the crown during the summer months. Their colour may be purple or yellow. The flowers add seasonal colour above the dark green stem. The supplied species account gives no fruit or seed details. Growers can raise new plants from seed in spring or summer. This is the propagation method given by the RHS. The evidence does not establish edible parts or medicinal uses. It also provides no species-level finding on toxicity.

Grow this cactus in a standard cactus compost that drains well. The RHS lists both sandy and loamy soils as suitable. It accepts an acid or neutral soil pH. Give it full sun or bright light filtered from direct sun. A sheltered south-facing or west-facing position meets the listed site needs. Water moderately from mid-spring through late summer. Apply a low-nitrogen liquid feed every six to eight weeks. The RHS assigns hardiness H2, with a minimum range of 1–5°C. It tolerates cool conditions but does not survive freezing.

The RHS recommends this plant for pots and patio displays. Its profile also places it among greenhouse and conservatory plants. It suits low-maintenance planting and needs no pruning. The RHS reports few general disease problems for this species. Mealybugs and aphids can still attack it. Check for these pests when tending plants in containers. Its modest size makes the container use a clear fit.