Zonal geranium
Also known as
Garden geranium, Horseshoe geranium, Common geranium, Pelargonium
Keep this plant’s care guide close at hand.
Get the appAbout Zonal geranium
Pelargonium zonale, commonly called the zonal geranium, is a tender, evergreen subshrub native to southern Africa and the main parent of countless bedding geranium cultivars. It forms sturdy, semi-succulent stems clothed in rounded, softly pubescent leaves marked by a distinctive dark “zone” or horseshoe band. Umbels of showy single or double flowers in red, pink, salmon, white, or bi-color appear over a long season in warm, bright conditions. In containers or borders it stays compact with regular pinching, and performs best in airy, sharply drained media. Though drought-tolerant once established, it flowers most freely with moderate, consistent moisture and balanced feeding. Not frost-hardy, it is grown as a seasonal annual in cold climates or overwintered indoors in bright, cool, ventilated quarters. Common issues include Botrytis gray mold, bacterial blight, edema from overwatering, and rust (Puccinia pelargonii-zonalis), especially in high humidity and stagnant air. Plants propagate readily from stem cuttings; seeds possess a feathery awn that twists into crevices. Lightly aromatic foliage and nectar-rich blooms attract bees and butterflies.
Taxonomy
Properties & Requirements
How to care for Zonal geranium
Water
Water deeply until excess drains, then allow the top 2–3 cm (1 inch) of mix to dry before the next irrigation. In bright, warm weather this may mean watering every 3–5 days in containers; in cool, low light, every 7–10 days. Bottom-water occasionally to keep foliage dry. Never leave the pot sitting in a saucer of water, and avoid saturated media, which promotes edema, root rot, and gray mold. Outdoors, aim for consistent moisture but accept brief, light drought between rains.
Light
Provide full sun to very bright light for 6–8+ hours daily to maximize bloom and compact habit. Outdoors, give morning sun and light afternoon shade in hot, inland summers; near coasts or in mild climates, all-day sun is ideal. Indoors, place at a south or west window, or under 10,000–20,000 lux of LED grow light for 12–14 hours. Insufficient light causes lanky growth and few flowers; gradually acclimate plants when moving between shade and sun.
Nutrients
Feed during active growth (spring through early autumn) with a balanced, water-soluble fertilizer at 1/4–1/2 strength every 2–4 weeks. For heavy bloom, alternate a higher-potassium analysis (e.g., 12-12-18 or 15-30-15). Avoid excess nitrogen, which drives soft, leafy growth and reduces flowering. Flush the pot monthly to prevent salt buildup, and reduce feeding markedly in winter under low light. Maintain slightly acidic pH (6.0–6.5) and ensure media contains calcium and micronutrients to prevent chlorosis.
Temperature
Best growth occurs with daytime temperatures of 18–24°C and nights of 10–15°C. Plants are frost-tender; sustained exposure below 5°C damages foliage and may kill roots, so bring containers indoors before frost. Overwinter in bright, ventilated rooms at 7–12°C to hold compact growth and deter pests. In hot spells above 30°C, provide afternoon shade, excellent airflow, and slightly more frequent watering. Avoid sudden swings from cold, wet nights to hot days, which encourage edema and leaf drop.
