André,
Have you considered adding another letter? (Create a 4 Letter system, AAAA, AAAB, AAAC, etc.). While adding just one letter my math shows it would go from 15,600 unique tags to over 350,000 just by adding the 4th letter. If I ever use all of my 15,600 in my system by tracking more than 15,600 plants I will add the 4th letter and keep going at that time. I feel that on my scale this will take years unless I start a hybridization
project where I track lineage. Is this why you would need more codes, are you hybridizing?
[Drumroll] Drumroll here [/Drumroll].... (Paul Wheaton does permies.com support in forum drumroll?)
This system allows for 1 cent plant tags! The copper washer idea I started with cost 10 cents each, by stamping pennies the cost comes to 1 cent per tag, I just need to drill a hole in the penny to hang it.
These 3 tags are assigned to Bocking 14 Comfrey at our farm, to be planted in 3 different beds
These tags are yet to be assigned, they will go to the next 4 plants or trees we get this winter (I need to drill hole in pennies to hang them)
These are the 'Tools of the Trade' that I use to punch the code
I'm so damn excited to farm full time!
-Josh
http://www.1880farm.com Central Texas, USDA Zone 8b, Temperate Grassland, 34″ annual rain, 52 acres of bottom land, with approx 4-5 acres in young woodland and 2.2 acres in ponds (or tanks, as they are called in Texas)