Abstract
Heat hardiness of 16 geophytes was assessed for use in landscape planting in Japan. The bulbs were planted in pots and grown in growth chambers under three simulated temperatures i.e. ambient air temperature in Osaka, ambient +5°C and ambient −5°C from July 9 or July 16, 1999 to September 20, then all of the plants were transferred to the outdoors. All of the +5°C Dahlia and Lilium ‘White Angel’ plants died. The other geophytes did not die under any temperature conditioins. Under higher temperature conditions, delayed sprouting of Muscari armeniacum, and Narcissus tazetta var. chinensis, decreased unfolding of leaves of Agapanthus africanus, decreased plant height of Muscari armeniacum and Crocosmia x crocosmiiflora, decreased number of shoots of Gladiolus, and decreased flowering percentage of x Amacrinum howardii, Crocosmia x crocosmiiflora, Gladiolus and Hedychium were observed. There were no significant effects of high temperature on growth of Allium chinense, Bletilla striata, Liatris spicata, Lillium ‘Elite’, Lycoris albiflora and Zephyranthes candida. Canna grew better under higher temperature condition.
