use a paint pen ... i get them at joanne fabrics or hobby lobby ... and staples ...

if you want to try poly.. it has to be UV proof ...

ken

i see sharpie now has their own paint pen

https://duckduckgo.com/?q=paint+pen&t=ffcm&iax=1&ia=images

I second the paint pen idea. The labels do need to be rewritten every few years. But it's still the fastest, most inexpensive and longest lasting solution I have found.

I use a labelmaker and have labels that last for years--brothers has several models and they use whatever color tape that you want in them.

i have some brother p touch labels going on 20 plus years ... they have been nearly completely destroyed ... lol.. but the labels are still on them

it is important to use the UV proof tapes ... i prefer clear with black letters ...

ken

Do you need a paint pen, or will a non-crappy permanent marker suffice?

I've bought plants with tags written in permanent marker, and after two years the writing is still there and doesn't look faded. The tags are just plastic, with no coating that I can notice. But my own sharpie-written tags faded after one very UN-sunny winter.