I assume that southern growers label a cultivar as a "hard" dormant when it goes dormant or stops growing early in the winter and does not start growing at all again until the spring. Classifying cultivars would be simplest if they disappear completely below ground when they go dormant.
Several cultivars have been described as being "hard" dormants (that I could obtain). When I tested them by bringing fans inside they started to grow quickly and without problem. A dormant that needed to experience a certain amount of cold to grow would not be able to start growing when brought inside before it experienced winter cold.
My conclusion so far is that daylilies are probably not hard dormants and do not require experiencing cold to break dormancy and grow normally.
The test for southern daylily growers is very simple. If you have a cultivar that seems to be a hard dormant (say because it is dormant in December and does not start to grow again until March) then take a fan of it inside as soon as possible after it has gone dormant and keep it at room temperature in a little water or a pot of soil. See if it starts to grow again relatively quickly. If it does then it was not a hard dormant (not endodormant) - it was only dormant because the temperatures were too low for it to grow (ecodormant). If it does not grow again (or if it takes months to sprout) then it may be a hard dormant.
