I'm having the strangest problem with my single impatiens this year. I planted several window boxes with them. The window boxes are on the north & east sides of my house and then some are inside a screened in porch. There is annual salvia and impatiens in each box. Now, my impatiens are wilting. They seem fine one day and then the next day they are laying down. The box in the porch started with one laying down and now they all are. The salvias are fine. Help! What should I do? I could rip out all the impatiens and replant but will the wilt come back?