|Sow in autumn, thinly, in modules or small pots containing a good quality, slightly gritty compost, barely covering with a little more compost. Keep outside over winter in a cold frame or sheltered spot (cold is needed for germination). Move seedlings into individual pots and grow on until large enough to plant out. Can also be sown in spring, in which case it may be beneficial to stratify the sown seeds in a fridge for a few weeks to aid germination. Inspect frequently and remove and pot up any seedlings that appear, then grown on until large enough to plant out. Germination can be erratic at any time of year, so do not be tempted to dispose of ungerminated seeds too soon! Established plants can be divided in autumn.