Pelargonium zonale aka Horseshoe Geranium

Pelargonium zonale is an evergreen subshrub in the Geraniaceae family. Its common names include horseshoe geranium and zonal pelargonium. It comes from South Africa, from the Cape to KwaZulu-Natal. There, it grows on dry, rocky hills and stony slopes. It also grows along forest edges. This species helped give rise to many cultivated zonal pelargoniums.

The plant has an upright, bushy shape. Garden plants reach about 3.3–4.9 feet [1–1.5 metres] tall. They spread about 1.6–3.3 feet [0.5–1 metre] wide. Against a wall under glass, plants can reach 9.8 feet [3 metres]. Young stems are fleshy, then become woody with age. The smooth, rounded leaves are mid-green. A narrow, darker green band marks each leaf. Plants take two to five years to reach full size.

Clusters of flowers rise above the leaves. Their narrow petals may be pink, white or purple. Outdoors, flowering falls in summer and early autumn. Warmth and bright light can keep flowers coming almost year-round. Remove faded flowers to help keep plants tidy. The bushy form suits patio pots and other containers. Plants can also live in a cool greenhouse or conservatory. The RHS also lists this species as a houseplant.

Give it fertile soil that drains well. Loam and sand both suit it. It accepts acid, neutral and alkaline soils. Choose full sun or partial shade in a sheltered spot. Soil moisture can range from dry to moist. The RHS rates its hardiness as H1C. In Britain, keep plants frost-free through winter. PFAF lists USDA zones 8–11, a broader hardiness range. Take softwood cuttings in spring or summer to raise new plants. Cut old plants back hard in spring to renew growth.

Wet soil can lead to foot and root rots. Grey mould, pelargonium rust and viruses may also cause trouble. Pests include vine weevils, leafhoppers, caterpillars, thrips, fungus gnats and aphids. PFAF records cooked leaves and stems as food. It gives the plant a low edible-use rating. It also records astringent uses for all plant parts. The plant provides an essential oil and has scented-plant uses. PFAF reports no known hazards, but this does not establish pet safety.