Linda. Just to clarify, your title is a about glads and begonias but your post is about glads and geraniums? I agree with Sharon Rose that pictures would help. If the gladioli have flowered it is normal for the leaves to turn brown and die afterwards. Your planting mix sounds like it may not hold water much, depending on the proportions. If it has been hot and dry wherever you are that could be the problem with begonias. I'm assuming the geraniums are Pelargoniums rather than hardy geraniums. It's not unusual for the older leaves on Pelargoniums to turn brown, but if more extensive than that it could indicate a problem. That's where pictures would help, as well as clarify which plants are having issues.