There have been several hard frosts in London this week; even Green Park in the heart of the city was dusted with white. In the garden Narcissus February Gold and Crocus tommasinianus flower early in the year and are untroubled by the freezing temperatures.
 Vernalization is an intrinsic part of the growing cycle of many hardy plants in temperate climates i.e. exposure to a period of chilling over winter.