At its best:
Jun, Jul, Aug
Fill a tray with seed compost, then sow a tiny pinch of seeds in each cell. Cover with a vermiculite, water and place the tray in a propagator in a warm spot such as a windowsill.
Once seeds have germinated, wait until two pairs of leaves form. Then, holding each seedling by its leaves and not its stem, transplant each one individually into a 7cm pot filled with sieved multipurpose compost.
Water seedlings well after transplanting and keep the pots in a warm, bright place. Avoid exposure to bright sunlight, which can scorch the young leaves.
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.