beckygardener said: Is there a term for high temp survival of daylilies?
Sorry, I don't know of a specific term for the survival of plants at high temperatures. Usually high temperature effects on plants are described as "heat stress" or "high temperature stress" or "heat tolerance". Possibly if the high temperature does not last for very long it may be described as "heat shock".
Daylilies will have both minimum cold temperatures that they can survive without damage and maximum hot temperatures that they can survive without damage.
Arisumi, investigated daylily growth at several different temperatures. He only used one cultivar and his tests used constant day and night temperatures (which is different from natural conditions where night temperatures are usually cooler). He used the cultivar 'Purity' and constant temperatures of 55°, 65°, 75°, 85°, and 95° F. The plants growing at 95° F did not flower. The plants growing at 85°F 'blasted' most of their flowers and opened only a few poorly formed flowers. He described their scapes as weak and as only half the size of the scapes formed at 75°F. Seed set was poor at 85°F.
[The speed at which plants grow depends on the temperature. At low temperatures plants grow slowly and at higher temperatures they grow more quickly. In Arisumi's experiment the plants at the lower temperatures were unable to grow enough to flower during the test period but for example, some of the plants grown at 65°F flowered two to three weeks after the end of the experiment. That would not have been the case for the plants grown at 95°F.]
