When I purchased daylilies from A Windsong Nursery last year they sent 3 samples of fertilizer which I then purchased because they said they would bloom so much better and would hold the color better. This is what I purchased:

21-5-21 to apply in Spring for plant growth and leaf enhancement

10-52-10 to apply in Summer to increase number, size, quality and maximum color of blooms

20-20-20 to apply in Fall to produce superior plant growth, with stronger & taller plants while increasing number, size, quality and maximize color of blooms

Last Fall after planting them I used the 20-20-20. Then this Spring I used the 21-5-21. The first bloom opened and the color was very faded, not even close to what I thought I was getting, and when I called they said I should quit using the fertilizers if the temps were above 85 F because the colors would not be as bright. The temps were already above 85 F.

Before I use any of these fertilizers again, has anyone else used them and what is your experience, and the best timing for each one if you know? Thanks.

Moved to Daylilies Forum..

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.

I agree with Larry, using high P (the middle number) when not justified by a soil test is not a good idea. Also it's questionable how much difference it might make to the number of blooms because the scapes start forming months before, often the previous fall. Exactly when the final bud count is determined though we do not know.

In the absence of a soil test I would go with the 21-5-21 since you already have it but a ratio (not necessarily analysis) nearer to 4-1-2 or 3-1-2 is often recommended for daylilies and that should be fine for all applications. When you've used what you have you might want to look at a slow-release fertilizer so that you don't need to make several applications. Nitrogen is the nutrient most likely to be in short supply but any element, even a micronutrient, that is below optimum could negatively impact the plant's performance. People are often surprised when they get a soil test to find that at least some of their nutrients are way too high in the soil and they are told to stop applying them. If you apply too much of certain nutrients it can cause a deficiency of other nutrients.

Edited to correct typos - I'd add rolling eyes emoji but can't do that when editing

Great info Larry and Sue. I think I'll get a soul test! I'm not good with this stuff so I was relying on what they told me, plus I called and talked to him on the phone about it before I applied it. I also always amend my clay soil with composted manure when I plant so I'm sure that made a difference too.