Hi Bec, and welcome
I only have a few daylilies right now, because my garden is mainly shady. I have four huge oak trees around the house, so only the middle of my back yard gets much sun. The daylilies require at least a few hours of direct sunlight to bloom well. So I've kept all mine in pots so that I can move them as the shady areas of my yard vary.
The soil mix, or potting soil is also fairly important for daylily health. When they're putting on their major growth in the springtime, it's important that they not dry out too much. Our native soil here is very sandy and dries quickly so you must amend if your daylilies are growing in the ground with major amounts of compost, pine fines, and other good organic amendments. Plus alfalfa pellets are fantastic for stimulating growth on daylilies in the spring - they are available at any feed store (it's horse food). If your plants are putting up good healthy leaves, it's curious that they aren't blooming. Are the clumps increasing in size? What are you fertilizing them with?
Daylilies are also affected by a rusty fungus disease here, because of our high humidity. I should modify that to say "some" daylilies are affected, because there are some that aren't. If your daylily leaves are getting spotted all the time, that might be what's setting them back and keeping them from blooming. You should probably ditch them and try another variety. My favorite (pictured here) is Siloam Double Classic - very vigorous, beautiful double flowers and seems to be completely resistant to the rust disease.
