Each tree that Old Growth Mill documents is given a tree number. It is the identifier that ties one tree to its record: the tag fixed to the trunk, the pin on the tree map, the blog post that follows it, and any conversation about it afterwards.
Six digits, YYMM## — year, month, and the sequence of that tree within the month.
260101
26 — the year, 2026 · 01 — the month, January · 01 — the first tree documented that month
January 2026 therefore runs from 260101 to 260199, which is a great many more trees in one month than this mill will ever work through.
Six is deliberate. An eight-digit number such as 20260101 cannot be told apart from a date, and a spreadsheet will quietly convert it into one. A tree number has to survive being engraved on a tag, written on a note, typed into an email and pasted into a column without turning into something else along the way. Six digits does that; eight does not.
The number follows the tree through the mill. When a trunk is cut into sections, each section is lettered from the butt end — 260101a is the butt log, 260101b the next one up, and so on. A slab, a cant or a mantle keeps the letter of the section it was cut from, so a finished piece can still be traced back to the part of the tree it came out of.
A tree number is a documentation reference, not an inventory label. A numbered tree has been found, located and recorded. It has not necessarily been cut, and the number says nothing about whether the wood is available, what it costs, or whether it suits a particular use. That distinction is the point of the system rather than a limitation of it — see why availability isn't listed and why documentation matters.
If you are asking about one specific tree, the number is the single most useful thing you can give. It matches the question to the right record, and it removes any doubt about which tree is being discussed.