At its best:
Jan, Feb, Oct, Nov, Dec
Plant out the seedlings to encourage them to put on growth before winter sets in. Space them at 10cm intervals in rows 20cm apart, and water well. If you don't have seedlings to plant out, you can usually buy plug plants from garden centres and mail order companies.
For best results, cover plants with a sturdy cloche. The warmer temperature inside will encourage strong plant growth in autumn, and protect them from the worst of the weather in winter.