I think that pencil markings last longer on plastic mini-blind slats than conventional Magic Markers do. My pencil markings are readable 2 years later (but do fade out after that).
They start out much fainter than MM ink, but sharper. I need the narrow-line sharpness because my handwriting is shaky. If it's wide-line as well as shaky, it's illegible. So I use mechanical pencils because they're always sharp, and I can choose a 0.9 mm, 0.7 mm or 0.5 mm width.
I keep my eyes open for the "Industrial" fine-point Sharpies, but don't want to pay S&H from Amazon just to try them out.
I'm fine with the messy look of mini-blind slats, especially on rows of vegetables.
I don't yet have many perennials whose names I know, for which I would need a truly permanent placard. And those few named perennials serve as the "landmarks" on my little maps, so i have their names written where they CAN'T fade: in computer files.
