Good ideas all around from everyone. I'm a fanatic when it comes to iris ID. It gets a little troubling if a marker comes up missing. This sometimes happens if an animal (raccoons, opossums, squirrels) get into a garden and accidentally drag one out. So if possible I try to get some pictures of the plants & labels for identity. Or at least get an idea where a certain plant is located in what row & what it's next to. This works for me since I roto-till the larger gardens. This might not appeal to everyone depending on personal preference. I try to take several pictures during bloom time & re-planting simply as a "back-up" source for ID.
These are all SDB's/MDB's and they are all tucked in for winter.
Photo is from late July 2018.
These were re-plants from 2017 blooming in 2018.
Three more rows were planted in July at far right.
This row of seedlings would be a mess without markers & (or photos).
SDB's are notorius for fast growth & growing into each other.
I have lost ID of several when they do this with no tag. As Lucy stated
above IB's do this fairly rapid.
Time to dig, divide & re-plant.