Answer: Most daylily experts suggest a minimum of six hours of sun a day for these plants to grow and bloom up to their full potential. Late afternoon sun, in my experience, has just not been enough to grow robust plants with decent bloom performance. If they are growing slowly, I suspect light rather than fertility or water is the limiting factor. To be honest, I don't think any amount of coddling will help make up for the lack of sunlight. In fact, extra fertilizing or watering would probably make the plants even weaker.
You might want to consider trying some other perennials which simply need less light than daylilies do. For descriptions, photos and cultural preferences of a wide selection of shade loving plants you might find the Shady Oaks Nursery catalog very inspiring. Their address is 112-10th Avenue S.E., Waseca MN 56093-3122; they have a site at http://www.shadyoaks.com/ and their telephone number is (800) 504-8006.
In the meantime, you might want to think about transplanting those daylilies to a sunnier spot.
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