Abstract
Freezing tolerance of ornamental bulbs and corms of about 50 species or cultivars which were native to different climates in the world was assessed. Almost all of the bulbs and corms native to the South Africa could not survive freezing below -3 or -5°C. This suggests that the mild oceanic winters do not provide the stimulus to evolve hardy bulbous plant species. Hardy bulbous species native to Mediterranean coast, Asia Minor and East Asia survived freezing between -5°C and -23°C. Allium oreophilum, Fritillaria camtschatcensis and Lilium dauricum were the hardiest of the bulbs tested, tolerating temperatures of to -20°C to -23°C. In the hardy bulbs, the base plate was the least hardy plant part. The flower buds were also far less tolerant than the leaf and stem in many ornamental bulbous plants. Further study on freezing tolerance of flower buds in bulbous plants is required.
