Stan,

It could be one of several things that I've experienced in the past. Maybe there is a tiny little insect pest infestation? Maybe you got mature plants and they're tired? Maybe they have root rot from too much moisture?

Since it looks as if they are doomed anyway, I would cut them back to where the stems are green, give them some partial shade and a weak fertilizer boost, and see what happens. You might also want to think about a replacement plant - just in case.

Mary

Thank you Mary. I belive mine are old as they were planted in early June. See no bugs, and now have given them a severe hair cut, as per your suggestion. Also have started applying more nitrogen, in hopes they were suffering. Lost your address from a recent computer change. Darn. Stan

Is there a drainage hole in the planter? I lost mine a couple years ago because the top gets dry but water collects at the bottom and the roots rot. It either rained in the pot or I over watered them or both. I will probably throw the urn shaped planter away, but have marigolds in there this year which are doing better. I pull it under the porch roof when it rains and control how much water they get. I didn't want to drill a hole in it because the drainage would stain the white plastic the way it is designed.

I don't think petunias, once they have matured or before, haven't grown any from seed since I was a kid, generally like that much water; they seem to tolerate dry soil rather well, probably one reason they are so prolific and popular.

You see lots of plants at malls and such that are in large planters that don't seem to have drainage holes in them, so that may not be the answer.

They do need good drainage - I keep mine moist, but not wet. I water everyday - in the morning. Don't water at night.

I use a timed release fertilzer mixed in the potting soil in the spring. They don't need deadheading - but will benefit from a pruning in mid July to keep them looking nice through the fall. Sometimes extreme heat will knock them back a bit if they are at all dry during the day.