|Each year I plant 80-100 impatiens. Around about the end of July/beginning of August, a few of the plants (6 to 10) appear to rot at the base and dye, but the plants all around the one that dies are great (16 to 18" tall). I use the same beds each year and some years I have little problem and other years its worse. They all get the same amount of water, feeding, and sun (they are planted under pine trees. I use dish detergent (SunLight) as a bug spray/controller, and that appears to help some.
By the way, just a comment. I see many beautiful impatiens down the seashore (Wildwood, NJ) that grow beautiful in full sun all day. I also plant them in full sun and have no problem (not New Guinea's either). They may wilt a little at the high ofthe day, but bounce right back. I have not had the problem I talked about above with the ones I plant in the full sun.
|Rot is caused by either fungi or bacteria, both of which thrive in soils that are too moist or where plants do not get adequate air circulation. You may be able to avoid the problem by spacing the plants further apart to increase air movement around plants and soil. It also helps to rotate plantings - plant diseases/pests build up in soil where only one crop is grown. Planting on a three-year cycle, or planting a mixture of species, usually creates enough diversity to reduce these problems. Try gaillardia (Indian Blanket), Phacelia, Forget-Me-Not and California Poppies for a change of pace. Hope this helps!|