Question
I have a large flower pot (about 42" diameter and 30" high) on my patio that usually smells bad when it is watered.  It sits on pot feet and seems to drain well.  It's planted with a hibiscus tree and is bottom planted with a mix of geraniums and lantana which all grow well and bloom nearly all the time.  Physan 20 decreases the odor but I have to use it every time I water which is every day in the Phoenix heat.  Do you have any suggestions for getting rid of the odor without taking out my healthy looking plants?

Answer
The odor is caused by the soil not getting enough oxygen, because it is getting too much water. That coupled with the heat will increase the problem that is there. Now you have probably killed not only the bad fungus with the Physan 20, but you may have killed the good fungus that breaks down the soil so that the plants can use the nutrients. These micro-organisms are important to the health of the soil and the plants.
Cool the soil if you can. Dry the soil if you can. But the best solution, since neither of those are probably going to be practical, is to change the soil to fresh, good potting mix. Then go easy with the water. Only water when the soil is dry. Let the oxygen get into the dry soil, down to the roots, then water. Try to keep the plants as cool as possible. Morning and early evening sun is fine. But hot mid-day sun is very hard on plants, unless they are a cactus. If you can keep them cooler you will reduce the need to water as often.