If your weather is like mine the temperatures have dropped the last couple of weeks and it's been more rainy/cloudy. That will slow down their growth. A couple of weekends ago I fertilized all of my plants with alfalfa right before a big rainstorm. That definitely helped their growth! So if you are very worried, apply some non-burning fertilizer (like well-rotted compost, worm castings, fish or kelp fertilizer) and wait for the sun and warmth to return. I'm sure your daylilies will start growing like crazy.
