From October to late February, sow seeds into deep pots or root trainers filled with a good-quality seed compost and place them in a cold frame. Pinch out the tips as the plants grow to encourage them to become bushier and produce more flowers, and harden off before planting out in early April. Direct sowing can also be made in October or March-April. It is important to remove the faded flowers before they set seed, so picking them to fill a vase inside will only encourage more to form.