I have some labels cut from old blinds that are still flexible after about 15 years use. However, I always use a No2 (HB) pencil to label my plants. I haven't found any pen that lasts as long as pencil in direct sun. Nick On Tue, May 26, 2015 at 7:48 AM, a van beek <avbeek1@hotmail.com> wrote: The only thing I can add is use a good waterproof marker. Some of them are > not so waterproof as claimed as I found out the hard way 2 years after > returning from holiday. > The person that sold me some succulent pelargoniums wrote the name with a > white ink marker on the black plastic pots. He told me that would last for > a least 4 years. I'm trying that now also. > > Aad > > >