Sow in trays of good quality, moist seed compost, 3mm (1/8") deep, in a propagator on a windowsill or in a greenhouse at approximately 18-21ºC (65-70ºF). For best results chill the seed in air tight plastic bags in a fridge for 2-3 weeks before sowing. Transfer seedlings when large enough to handle into further trays spacing them 5cm (2") apart and grow on. Plant outside in late May-June, when frosts have finished, about 40cm (16") apart. Sow in August-September and overwinter undercover for earlier flowers the following year.
Ideal for beds and borders, patio pots and containers. Attractive to butterflies and bees. Suitable for cutting. Prefers full sun or partial shade. Cut back flower stems when blooming is complete and mulch around the base in the autumn.