I love to divide my iris bulbs every fall. This is the time of year to do it. Dividing bulbs not only gives you more lovely flowers come spring but helps the existing bulbs to bloom more. Every year I divide the same area and each spring the bulbs bloom more than the year before.
The best dividing tool is a large fork spade. Just dig gently down below the bulbs and lift. You will see the bulbs and can just scoop them up with your hand once they are unearthed.
When you replant put the flat end down and just recover the area you divided from.
This is the area I divide from each fall and you can see I still get loads of blooms come spring. This is an easy and free way to add more blooms to your garden.