For the last three years my impatiens' leaves turn yellow, get black spots and then die. In addition, my black eyed susan's get black spots and then the leaves turn black and appear burned. Could there be something in the soil? Why is this happening?
The problem on your black eyed susans sounds most like septoria leaf spot, a common fungal disease. The spores of this fungus can overwinter in the soil, so it helps to remove all dead foliage in the late summer or fall. Avoid wetting foliage during the growing season, and improve air circulation around the plants to cut down on infection. You may also need to spray plants with a protective fungicide before they begin to develop the symptoms.
The problem on your impatiens could be alternaria leaf spot, also a fungal disease. Control is similar to the steps outlined above for septoria leaf spot. The impatiens could also be affected by impatiens necrotic spot virus. Because this is a virus rather than a fungus, fungicides would not be effective in controlling it. The virus is spread most commonly by thrips, tiny flying insect. Getting rid of affected plants and controlling the insects is the best means of preventing impatiens necrotic spot virus.