This is a subject that has haunted me for years. I have been using metal mini blinds cut into about 8 inch strips. I just use a sharpy to mark them. This doesnt work at all for me. The mini blinds heave out of the ground every winter and the sharpie doesnt make it through the spring. My irises are a mess! I have a bucket of labels that belong in the garden. I have made maps of all my plants but it only gives the general area of each irises location. Since most of the irises are growing so close to each other now its not much of a help. To make matters worse the irises arent blooming well because the soil is worn out. I plan amend it heavily this summer. Not looking forward to all that digging. So with all that said getting the irises correctly labeled is going to take at least 3 to 4 years, at least!
After doing some research at Daves Garden and other sources I have discovered the magic of the p-touch labeler by brother. Amazon carries them and has good prices. I plan to buy one immediately. Then i will head over to Office Max and pick up the weather proof 3/4" tape. After printing i will affix them to Paw Paw markers. Many say the labels will last 5+ years in the garden. Problem solved!