It would not be unusual for containerized plants to need a daily soaking in the heat of the summer. If you are watering that often because they NEED it, it's not a problem. Also, if your potting medium is a fast-draining mix, then over-watering is not something you usually have to worry about.

So, only you can be the judge of the over watering issue. Is the potting medium still moist from day to day, and you are watering out of habit? Is your potting medium slow to drain with the water pooling on top before slowly leaching through the container?

I have to water ALL of my container plants every day in the summer, unless it rains. Some get it more than once a day, but they are planted in very shallow or small containers. I consider it a GOOD thing, and not a problem. (Plants love all of that fresh oxygenated water!)

Questions for you: is the 'white' on your petunias a surface problem and can be wiped off OR are the leaves actually losing pigment? Is there any way that you could take a picture so that we can see the problem?

Thanks for your message Rhizo. I've was watering my containers without checking if they are dry or not. So I am now checking, and usually they are dry. I don't know if this is true, but a friend told me that when water runs through containers, it can leach out nutrients in the soil.

The foliage is actually turning white, I cannot rub it off.

I appreciate your help!

is the white area.. somewhere where water stood on the leaf in full sunshine???

really need a picture ...

ken

There are many reasons for leaves to go white. A good, close picture may help. Calcium deficiency, other severe mineral deficiencies, extreme choloris, the feeding of certain insects, air pollution damage including sulfur and ozone, water sitting on the leaves and leaving a residue when it dries, powdery mildew.

check out the link below and see if this is what your petunia leaves are doing. It's a syndrome seen in the newer vegetatively propagated petunias. They have lower pH requirements than their seed-grown predecessors and tend to display symptoms of iron deficiency more quickly because if the pH of the soil is not to their requirements, iron becomes unavailable and iron is needed for photosynthesis, what makes a leaf green. I have seen this occasionally in greenhouses in old hanging basket petunias taken off constant-feed and resulting in higher soil pH levels, resulting in snow white new foliage.

Here is a link that might be useful: Iron deficiency in Greenhouse Crops