hellpmaggie,
Your irises are Dutch Irises. When the flowers age and die, the foliage will turn brown and die too and then the bulbs go into dormancy for a few months. There are some dead flowers in your photo and I suspect they are the ones that have the brown foliage.
Some nurseries who sell Dutch Irises also provide information about to grow them. For example:
https://www.easytogrowbulbs.co...
This one mentions using Blood and Bone in Autumn
https://www.tesselaar.net.au/g...
This one recommends applying Bone Meal during the bloom period.
https://www.doityourself.com/s...
