Hemlady said:So if a plant dies down after flowering, is it considered dormant??
A plant that flowers and then stops making new leaves is dormant (biologically meaning it is not growing). If in addition to not making new leaves its current crop of old leaves yellow and die and it is described as having died down then it is still dormant. When it starts making new leaves (sprouts) it is no longer dormant.
If by "considered dormant" you mean that the plant would be registered as being dormant then that depends on the hybridizer, their location and the time at which the daylily sprouts the new leaves.
Biologically dormancy is a mechanism that plants use to deal with times of the year that may be harmful to the plant if it was trying to grow. Examples of those sorts of times are very cold winters, very hot summers, droughts, etc. Some plants anticipate those times and form protective buds and stop growing before those periods start. For example, neither an evergreen tree like a pine, nor a deciduous tree like a maple, tries to grow during a cold winter. They both grow during the summer, then form buds. The evergreen pine keeps its needles (leaves) during winter while the deciduous maple loses its leaves in the autumn. Often the plants stop growing (making new leaves) a surprisingly long time before winter arrives.
To make certain that the plant does not try to sprout during mild spells in the middle of winter many plants must experience a certain amount of cold (chilling) before they can sprout. For example there are different varieties of apples with different chilling degree requirements and one chooses which variety to grow depending on the amount of chilling the variety requires and the amount it can get in the location where it will be grown.
Stout provided some suggestive evidence that some older cultivars and some species of daylilies might require some chilling to sprout. However, he also showed that by about mid-November in New York no daylily required any chilling to sprout. He did this by bringing a number of different daylily plants into a greenhouse and they all sprouted quickly. I have tested several daylily cultivars by bringing them inside in mid-October and they all sprouted quickly.
This year I will test modern daylily cultivars in mid-September, mid-August and mid-July to check if there are daylilies that require chilling to sprout. I hopefully will also be able to check some daylily species.
So far I have not found any daylily cultivars that require chilling to sprout. That suggests that daylilies are "dormant" during cold periods only because the temperatures are too low for them to be able to grow and not because they are biologically dormant. It also suggests that different cultivars have different minimum temperatures for growth.
