Last year we took the problem of tomato cages head on and solved the dilemma once and for all. Paco made me 30 welded wire tomato cages. This year we used every one of them. The size of the tomato plants in their sturdy cages quickly eclipsed the markers I had placed near the bases. This year I transformed some thin kitchen cutting mats, cable ties, and a garden marker into some nice eye level tags that will last the season. I hope to reuse them if I can find something to strip the marker.
Every year the garden gets better and better because we learn and innovate. We know we still get some things wrong, but we get a lot right now too! More on this upcoming posts.
Small Wonder Nutrition 
You might try nail polish remover on the garden marker and see if that will remove it. It works remarkably well on Sharpie (esp on plastic), so I’d guess it’ll work for this too! Good luck.
Thanks! That’s what I was thinking, thanks for confirming it.