Top Leaves Of New Guinea Impatiens Are Getting Brown Spots

Question From: J. Witherow - TENNESSEE
Q: Earlier this summer I realized my New Guinea impatiens were getting too much sun even tho just morning sun, it was very hot. I moved it to an area with filtered morning sun and shade in afternoon. The top leaves continued to get brown spots so I cut it back. Pictures r attached. I’ve spent almost an hr trying online to know how to treat. I’m not seeing mildew or bugs so I was thinking I need to repot & make sure it isn’t root rot. Please advise. I love these plants but never have much luck keeping them at their best.
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A: I see no sign of disease. New Guineas need some sun in order to bloom. Eastern exposure is the best. Morning sun and afternoon shade. The soil must be kept moist. If allowed to dry down they will cease blooming and die back. That may mean watering them as often as twice a day in high heat. They are also heavy feeders and should be fertilized every three weeks with a good water soluble fertilizer according to package directions.  You might also contact the University of Tennesee extension in your county for more advice about growing in your area. Best And Happy Yardening, Nancy