How to grow geranium
Overview
Geranium (Pelargonium zonale) is a herbaceous perennial grown for its colourful flowers, scented foliage, and seasonal display. It is ideal for filling gaps in garden beds and thrives in full sun with minimal water.
Varieties
- Pelargonium zonale 'Appleblossom' — Pink-and-white flowers, compact habit, ideal for pots.
- Pelargonium zonale 'Vancouver Centennial' — Variegated foliage with orange-red flowers, striking in containers.
Soil Preparation
Geranium prefers slightly acidic to neutral soil (pH 6.0–7.0). Enrich with compost for drainage; avoid heavy clay. In pots, use a quality potting mix with added perlite.
Growing Guide
Plant geranium in full sun with well-drained soil; space 30–45 cm apart. Water sparingly once established, allowing soil to dry between waterings. Avoid wet feet by using raised beds or pots in heavy soil. Deadhead regularly to extend blooming.
Sowing
Sow seeds 3 mm deep in seed-raising mix; germination takes 10–14 days at 20–25°C. Transplant when 4 true leaves appear. Direct sow is possible in warm climates after frost.
Care
Feed with a balanced slow-release fertiliser in spring and early summer. Deadhead spent flowers regularly and prune leggy growth in late summer to maintain shape and promote fresh foliage.
Companion Planting
Geranium pairs well with petunias and alyssum, which share similar sun and water needs. Avoid planting near heavy feeders like tomatoes that may compete for nutrients.
Common Pests & Risks
Caterpillars and whitefly can attack geranium; treat with neem oil or insecticidal soap. Rust appears as orange spots on leaves—improve air circulation and avoid overhead watering. Remove affected foliage promptly.
Troubleshooting
Yellow leaves: overwatering or poor drainage—reduce water and improve soil. Brown leaf edges: underwatering or sunburn—increase water or provide afternoon shade. Leggy growth: insufficient light—move to full sun. Rust spots: fungal disease—improve air circulation and remove affected leaves. Whitefly: treat with neem oil weekly.