Use a #1 lead pencil rather than a marker. Pencil has never faded off of a label for me. The label will crumble and/or disintegrate before the pencil lead will fade off of the label. The lead of a #1 pencil is very dark (and it is much softer lead than is in a standard #2 pencil).

For labels that will really last, buy some old vinyl mini-blinds at a garage sale (or save one of your own) and then cut them into usable labels. Mini-blinds are treated so they won't break down in the sun and a pencil will write on a label really well.
Good luck,
Mike

Oops...I meant that a pencil will write on a mini-blind really well.
Mike

Thanks Greenthumb, wish I had posted sooner. This place has been so good to me.

I use Mike's method too.

I also use a Uchida DecoColor opaque paint marker pen on 'bleach bottle' labels. That plastic is extremely durable. So far, 3 years, the label is good.

I bought the Uchida pen at the local hobby store. About $3.50.

I like my markers to look pretty too, so I get creative. I use saladforks and V8 cans or other aluminum cans that don't have a deposit. I use tinsnippers to cut into top, then I cut a big rectangle out of the aluminum, cut it in half, fold edges over, write on it with very sharp pen and wedge it in between the tines. It looks almost like punched tin and will last for years.It looks like a piece of art instead like a mini blind LOL

I found a one in. wide blind at Big Lots, a dozen no.1 pencils. For $6.00 I figure I can make 300 markers. I also got some cute bug stickers and various colors of permanent markers for decoration. My markers just look so great. Thank you for your very good suggestions.

I rescued an old metal-bladed venetian blind - aluminum? - with baked-on enamel finish. Cut into desired lengths, can write on it with a 'permanent' marker, or use a nail(or an engraving tool, if you must) to scratch the ID, etc. into the enamel finish - that's REALLY permanent!