Specialty Gardening: HELP: Snowstorm annuals barely making a flurry, 1 by peony8

peony8 wrote:
I usually hang impatiens, but this year I wanted to try something whose dropped petals wouldn't be so hard to clean off my porch floor.

On or around May 1, I purchased three of Snowstorm 'Pink'.

For most of the month of May, they bloomed profusely and continuously, but the last 10 days or so, they have started to look very disappointing.

I fertilize twice monthly, alternating basic container fertilizer (MiracleGrow) with Neptune fish stuff.

The tag says deadheading not necessary, and they take sun to part shade. All three are in part shade with a bit of direct morning sun.

Any ideas what is wrong?