Soak seeds overnight in warm water before sowing 1cm (Â½in) deep, 3 seeds per 7.5cm (3in) pot, in free-draining, damp, seed compost. Place in a propagator or seal container inside a polythene bag and place at 20-25Â°C (68-77Â°F) until after germination which takes 10-21 days. Do not exclude light. Spring sowings can be sown outdoors, 2.5cm (1in) deep, in drills 7.5cm (3in) apart.
Overwinter October sown plants in cooler conditions such as a coldframe before planting out in spring, when the ground has warmed, 23-30cm (9-12in) apart. Pinch out the growing point once the second pair of leaves has opened. Water freely in dry weather. Remove faded flowers regularly to encourage more blooms.