It's easy to get lazy, especially when planting in a frenzy... I tell myself "I'll map this year" and "I'll make a permanent label later". Sometimes, later is a long, long time. And those plastic strap labels have a way of not only fading, but walking away in the meantime. One spring, a birdnest blew down in our yard and intertwined with the twigs were plastic strap labels!!! So forever more, it's not my fault when a label goes missing.... I blame the birds.
