yellow irises

Remove the seed pods and then leave the plants as long as you can to die down naturally. That way all the strength of the plant will be put into the corm you will need for next year, and the corm will have a chance to ripen in the sun.

If they are Bearded Irises, I would in September cut the leaves in a fan shape to about 8 inches and clean up any dead leaves leaving the corms nicely exposed to any sun. It is also a good time to divide them ,take out most of the Iris to a strong corm and then the ones you remove tidy them up and replant the good ones making sure the corm is facing the sun.