I think what works in one garden could destroy the plants in a garden with totally different nutrient requirements. If your garden is already high in phosphorus, I would certainly not be adding 10-52-10. It is unusual for most gardens to be high in nitrogen so I think it would be a safer bet to use the 21-5-21. For gardens with no soil test run, the normal route taken by a lot of gardeners is to use a balanced fertilizer like 10-10-10, or 20-20-20. As almost everyone says and only a few actually do, getting a soil test is considered the best course to follow. Because of the tons of organic matter I have added every year over the past several years I feel I need the extra nitrogen. Just remember that fertilizer affects the entire plant, no just the blooms. If the roots and the foliage are not happy the blooms will not be either.
However, all that said, no matter what fertilizer you use, no matter where you live or what daylilies you grow, I think you can expect a lot of the first flowers to bloom in spring will be faded in color, distorted and unrecognizable. That is just the nature of the beast so to speak. Normally as the weather warms and the days get longer and the plants mature and are not producing "first flowers ever", things clear up and the blooms become like the ones you were actually expecting them to be.
