I find that plastic in any form does not last in the southern sun. It becomes brittle and any type of marker uses except carbon pencil fades and must be redone. I buy the heavy duty rose markers and write on them in pencil. so far so good. I also map. If I have two of the same cultivar I do not like to make two metal markers so I use one flexible plastic one and shove it in below soil level. It seems to hold up much better without exposure to the sun. A friend with a large iris garden hammers PVC pipe into the ground near her clumps with the name written in paint on the north side to protect the letters from the suns rays. she says that method lasts for many years. I do not use that method because I am need to get into the beds and do not want to trip and fall on a piece of PVC pipe.
