Question
I am using 18in. plastic pots with a styrofoam plate approx.8in. from the bottom to make the pot lighter to plant impatients.The pots get full sun until noontime I use Miracle Grow potting soil ( fresh soil each year )My problem is that for the past 2 years around the middle of July the leaves start to get browwn circular spots on them I attempted to remove the affected leaves as I noticed them but was unable to control these spots.Now the entire plant is affected by theses spots with some of the leaves turning yellow.The plants grow great( 2ft.tall) and flower well until this problem begins even the unopend blooms are affected by these spots.I only water in the AM and not until I feel that the soil is dry.I plant approx. ( 10 ) plants in each pot in the spring.I had the same problem last year and discarded the soil and cleaned all pots with bleach prior to planting this season I have other impatiants planted in other pots usualy used as a border around other plants and do not run into the problem I have with my Impatients only pots.Thank You for your help
Pat

Answer
Patrick,
I usually see this type of leaf-spot fungus on plants that are getting their foliage splashed with water frequently. Since your pots are probably drying out every day and you have to water every day, if you're getting the foliage wet when you water this will provide the perfect place for fungi to grow.  It could also be that these pots are in a place where there isn't as good air circulation and this can contribute to fungal growth as well. And finally, be sure that there isn't some source of dripping water on them at other times, (air conditioner, lawn sprinklers etc).

You're doing everything else right - new soil, AM watering etc, so my guess is that there isn't as good of air flow in this location. Try watering by sticking the nozzle just over the lip of the pots so that no water gets on the leaves, and make sure that no drift from nearby sprinklers etc are getting the plants at other times.

I hope this helps,
C.L. Fornari