Surface guide
QR codes on plant tags and garden markers
A garden QR code faces UV, rain, frost and soil splash. Use error correction H, a UV-stable material, and expect to replace printed tags every two seasons unless you use engraved or anodised metal.
| Typical scan distance | 20–40 cm |
|---|---|
| Minimum code width | 2–4 cm |
| Error correction | H |
What actually degrades
| Factor | Effect | Mitigation |
|---|---|---|
| UV | Ink fades, plastic yellows | UV-stable ink and substrate; the code fades before the tag does |
| Rain and soil splash | Obscures the pattern | Mount at 15 cm+ above soil; angle to shed water |
| Frost | Cracks laminate, delaminates labels | Anodised aluminium or engraved plastic |
| Algae and lichen | Reduces contrast | Matt surfaces clean more easily than textured ones |
Materials, by expected life
- Laminated paper: one season. Fine for annual bedding.
- UV-stable vinyl on rigid PVC: 2–3 years.
- Engraved two-colour acrylic: 5+ years, and contrast is structural rather than printed.
- Anodised aluminium (photo-anodised or laser-marked): 10+ years, the standard for botanic gardens.
Specification
- 2–4 cm — visitors lean in, so the distance is short.
- Error correction H, because partial obscuring by leaves and soil is routine.
- Matt finish; a glossy tag in direct sun is unreadable.
- Angle the tag 15–30° from vertical, facing the path. Flat tags collect water and debris; vertical ones are scanned at a steep angle by someone standing.
What to link
A page that survives replanting: the species page, not "the plant in bed 4". Beds get redesigned; species do not.