Specialty Gardening: Window boxes plantings not doing so well., 0 by Niere

Niere wrote:
Hi--I was hoping to get some help in this forum. Last fall we put up four copper and wrought iron windowboxes. They are on the second story of our home and are south-facing. Each box is about four feet long. At the beginning of the summer I put MG potting soil in each box and planted each box with three electric pink geraniums, three very dark purple wave petunias, and two lemon symphony osteopermums. I've been fairly religious about watering and feeding (watering two to three times weekly as needed, feeding once a week with MG) and I've tried to stay on top of dead-heading with the geraniums. I was told that I would not need to dead-head the wave petunias or the osteopermums. Well, the geraniums are fine but the flowerheads are not as large as they initially were, the osteopermums have petered out and some of the petunias are "okay" and some have stopped blooming altogether. I'm very disheartened by all this--I made it very clear to the lady at the nursery that I needed plants with a lot of "pop" (the boxes need to be seen from 100' away) but they also needed to be relatively low-maintenance as I can't be doing tons of dead-heading or trimming to plants that are hanging out a window from a second story. Did I underfeed or overfeed? What did I do wrong? It's so frustrating to me when I see other people with petunias hanging out of their boxes with just waves and waves of blooms and mine have petered out. I've pretty much given up for this year, but any suggestions for next year would really be appreciated. Thanks!

Here's a picture of what they looked like--along with hubby!-- about a month ago...