Answer: Even though you transplanted them at the same time into similar soil, I suspect the one that is just sitting there is not getting quite the right growing conditions. It may be that the soil isn't draining well - or is draining too well and not providing the moisture and nutrients your Stokesia needs. I'd feed it with a liquid (or foliar) fertilizer. If you see no improvement you may want to dig it this fall, amend the soil with compost or other organic matter and then replant it. That should prompt better performance next spring. Good luck with your plants!
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