I didn't think my flower boxes and baskets did as well this year. It was very disappointing as I did the same thing as in years past...except I used Bonnie's Pro Mix Potting Soil instead of Miracle Gro with moisture control.
I had about decided to plant something different next year when Larry pointed out I'd changed potting soil. That may be it. It makes better sense than the plants were tired of being there. They were spindly rather than lush and the color wasn't as deeply green.
I'm going to go back to Miracle Gro Potting Soil next spring and for my greenhouse this fall and winter.