You could simply water with your solution next time and avoid the possibility of damage. Let your plants take up the chelated iron via the roots.

I'm sorry that I don't know the answer to your immediate question, but I'm sure that someone will be able to help.

Thanks for a response. I'm actually doing both a foliar spray and applying a solution to the potting mix, but the later could take so long to work that the plants will become unsightly due to loss of leaves.

I found the source that indicated sunlight inhibits chelated iron being absorbed by leaves (see below). All it says is, 'Chelated iron sprays are inactivated by sunlight.'

Still wondering about the direct sunlight after foliar spraying with chelated iron. When is it generally safe to put plants back in direct sun to avoid scorching?

Here is a link that might be useful: http://www.ext.colostate.edu/mg/gardennotes/223.html

This post was edited by peterk312 on Mon, Jul 8, 13 at 18:53

As a general rule of thumb plants can be put back into sunlight when the leaves are dry after being sprayed by most anything. Contrary to myth plain water will not magnify the suns rays and "burn" the leaves, although some chemicals mixed into water may cause similar problems while wet.
"Scorch" is a problem that occurs to a plants leaves if the plant cannot supply adequate amounts of water to the leaves to replace that lost to transpiration.