Sow the seed thinly direct into finely raked, moist, warm, weed-free soil where the plants are to flower 13mm (½") deep. Germination takes between 10-15 days. As the seedlings develop, thin them out in stages to achieve a final spacing of 23-30cm (9-12"). For early flowering the following year sow direct August/September where the plants are to flower. Deadhead throughout the season to encourage continual blooming until first frost.