I'm having the same problem this year and I blame it on all the rain we've been getting. A certain number of leaves yellowing is normal and nothing to worry about, but if you're getting a lot of it, you're probably overwatering. Don't water until the top inch or so is dry. Geraniums are quite drought-hardy.

Janet's Garden

Have the same issue here for the ones in plastic pots. If you're in an area that is prone to lots of rain, consider switching the Geraniums into clay pots. They'll be much happier and will look a lot better for you.

My younger Geraniums have the same issue as what you described. But my 20yr. old one doesn't seem to care one way or the other. That one's thriving. Go figure! The really young ones which are in clay pots, show no signs of problems. And the only issue that plagues them is the amount of rain we've had.

Also, note that Geraniums don't like heat. It's quite common for them to lose a lot of leaves when the temps start to soar. When that happens, you can actually cut them back and they will grow new braches and leaves.

Hope that helps.

Thanks so much for the info..it has been raining alot AND the temp have been up in the ninetys. I will try watering a little less and next year I will try the clay pots. I feel better now :)