Answer: Daylilies such as this thrive in evenly moist yet well drained soil that is also quite rich. They bloom on the new growth, so as long as they keep developing new fans they will continue blooming. The plants in the ground may have less sun, drier soil, less fertile soil, or may be older and need dividing. The reblooming types seem to bloom best if divided every year or at least every other year. In many cases, it is a combination of factors. Topdressing with good quality compost can help for now, if they need dividing you could do that at the end of August and replant into amended soil.
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