How to Grow Geraniums From Seed

Growing pelargoniums (tender geraniums) from seed is perfectly achievable at home, though it requires more patience than taking cuttings. The reward is a batch of plants from scratch — useful when you want lots of new plants without relying on cuttings from existing stock, or when trialling new varieties sold only as seed.

When to sow

Pelargonium seeds need sowing early — January or February — to give plants enough time to develop and flower in their first summer. Sowing later than March significantly reduces the flowering period before autumn. Hardy geraniums (cranesbills) can be sown in autumn for germination in spring, or in late spring once soils have warmed, though germination can be erratic and they may not flower until their second year.

Sowing pelargonium seeds

Pelargonium seeds germinate best at a consistent temperature of 21–24°C, so a heated propagator or a warm windowsill is essential in January and February. Sow individually or spaced out in trays of fine seed compost, press lightly into the surface, and cover with a very thin layer of vermiculite or compost — no more than 3–5mm. Cover with a lid or clear plastic to maintain humidity and exclude draughts. Germination usually takes 7–21 days; keep the compost consistently moist but not waterlogged.

• Sow January–February for summer flowers.
• Maintain 21–24°C for germination.
• Cover very thinly — seeds need light to germinate.
• Prick out seedlings when large enough to handle.

Growing on seedlings

Once seedlings have two true leaves, prick them out carefully into individual small pots of multipurpose compost. Keep them in good light — a bright windowsill or under grow lights — to prevent legginess. Pot on into larger containers as roots fill the pot, and begin feeding with a balanced liquid fertiliser once they are established. Pinch out growing tips when plants reach 10–15cm to encourage bushy branching rather than a single upright stem.

Seed vs cuttings

Seed is the slower route: plants take 16–20 weeks from sowing to flower, and seed-grown pelargoniums can show some variation in colour compared to F1 hybrid parent varieties. Cuttings produce genetically identical plants to the parent and root in 3–4 weeks. The main advantage of seed is scale — from one packet you can raise dozens of plants cheaply. Many F1 hybrid pelargoniums bred for seed production are also very uniform and floriferous.