At its best:
Jun, Jul, Aug, Sep
Fill a tray with seed compost, then sow a tiny pinch of seeds in each cell. Cover with vermiculite, water and place the tray in a propagator in a warm spot.
Once seeds have sprouted, wait until two pairs of leaves form. Transplant each seedling into a 7cm pot filled with sieved multi-purpose compost.
Water well after transplanting and keep the pots in a warm, bright place. Avoid exposure to bright sunlight, which can scorch the young leaves.
Many varieties sown indoors by March or April will start to flower as early as June.
When all risk of frost has passed, move the plants to a cold frame or patio, bringing them in at night. After a week you can plant them outside.