Hi! Have read with great interest some earlier postings relating to this same topic. I experimented this past season (before having Ideas Genie) and created labels for labeling plants either by tying them to a stick, or putting them in the soil in the pots. I used M/S Word mail merge program, and used the address form template to create 3-line labels.
By using abbreviations, codes, etc., my labels contained - ID#, type of plant, plant's name, manufacturer/grower, source, specie, color, year purchased, etc. Printed by Epson Ink-Jet on Avery #5366 file folder labels, full sheet, 30 on, 2/3"x3-7/16" all white labels. The ink used is manufactured by Epson call DuraBrite, comes in both black and color, supposed to be waterproof, last longer, no fading, etc. The only drawback is that you have to purchase an Epson Printer to use the ink.
The label was attached to white green house markers, 5/8"x6", with it's own adhesive, then wrapped with 3M (Minnesota Mining) #3750, clear 1-7/8" wide, heavy duty packaging tape. One ply on the label side, with the marker centered in the middle of the tape, then the two sides wrapped one after the other around the back. The label was attached to the marker about 1/2" down from the top end, leaving space at the bottom of the marker to place in the soil. When applying the tape, the tape covered the end of the label, but left the point end uncovered. I put the tape on as smooth as possible, and pressed down on it to make the best seal I could. The last step was punching a 1/4" round hole 1/2" down from the top end. The tape also was extended past the top of the marker about 1/2" and sealed tightly.
At this point in time, they are sitill out in the weather, black ink is standing up great and the tape has held up. They have been rained on, full sun, and frost, and have held up for this past season. I am going to experiment with other laminating materials, if anyone has ideas let me know. I was not able to test the color ink because of not having the programming at that time to do it.
In summing my posting of this topic, what I see first of all, is ask yourselves how you are going to use your labels, what do you want on them, and how long does it have to last. For my use in propagating, probably one season, a color picture would be nice, and the info I listed previously. For somebody that has their garden(s) open to the public, or for tours - what do you need? For somebody raising plants for resale - same questions. Maybe by the time we're through we will come up with 3 or 4 basic concepts, by size, info, lasting qualities, etc. There are a lot of materials out there out there to experiment with, a lot of info on the Internet. IdeasGuy's classes on seed starting will surely contribute to the discussion. Hopefully we can find label/markers that are economical to produce and contain the most important elements.
On a related subject: If you need a black marker to mark on the green house markers, or for that matter any material, that will hold up and be waterproof, ask your local gardener's source for a marker made by DP Industries, #GM08, labeled Garden Marker, it too held up very well. Be sure and cap it immediately after using, and it is toxic so use outdoors. It might be available in colors also.