@Suzyp831
Unfortunately the way daylilies are described does not necessarily relate well with how daylilies grow. Foliage is one of those characteristics that is misleadingly used. If you look at how daylilies are registered you will see a category called "foliage" That has three possible descriptions. Those are dormant, evergreen and semi-evergreen. But those categories do not describe daylily foliage. They do describe how daylilies grow. The leaves are the same no matter how the daylily was registered for foliage.
A daylily plant that was registered as dormant means that the plant stopped growing new leaves, formed a bud and rested for a time before starting to grow new leaves again. A daylily registered as evergreen does not stop producing leaves to form a bud. A semi-evergreen may act as a dormant sometimes and as an evergreen at other times.
The catch is that whether a daylily plant is going to stop producing new leaves and form a bud may depend on the temperature, the length of the nights or both.
The "foliage" type of a daylily is a description of how that daylily grows in the location where the hybridizer of that daylily grew the daylily when they registered it. The possibility is that a daylily can act evergreen in a location with mild winters but act dormant in a location with colder winters as one possible example. Or it might act evergreen in a location where the nights are not longer than 13 hours but act dormant where the nights are longer than 14 hours as a different possible example. We do not know what specifically determines how any daylily grows in any location. That is we do not know the biological basis for the different types of growth habits shown by daylilies (dormant or not dormant = "evergreen" but should be evergrowing)
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Now we come to the part that makes the situation even more confusing.
In the past there was a tendency for hybridizers in the more northern parts of the U.S. to hybridize using daylilies registered as dormant as parents and for those in the more southern parts to hybridize using daylilies registered as evergreen as parents. Hybridizers in the north cannot select for daylilies that grow and flower well in conditions that exist in the south. Hybridizers in the south cannot select for daylilies that grow and flower well in the conditions that exist in the north. So each hybridizer produces daylilies that are better and better adapted to the conditions in their locations and less well adapted to the conditions elsewhere. In the past, two hybridizers (one from the south and one from the north) saw this and started to use each others daylily introductions in their crosses to produce daylilies that were better adapted to the alternate conditions of the other hybridizer.
As long as hybridizers in each location often specifically use daylilies hybridized in other regions in their crosses their daylily introductions will be adapted to grow in a wider range of conditions. When hybridizers in each location do not use daylilies from hybridizers in locations with different growing conditions than their own, as parents in their crosses then their introductions will become better and better adapt4ed to their own growing conditions and conversely worse and worse adapted to other growing conditions.
Hybridizers could manage to avoid producing daylilies with strong local adaptation and poor wide adaptation by rigorously testing their own introductions in other growing conditions and only using those that do well in several different growing conditions as parents.
