Plastic labeling stakes, available at any nursery are very durable. Sharpie ink is not. So, I bought a P-touch labeling machine -- very reasonably priced at Office Depot or Office Max. With 3/4" tapes, you get two rows on the labels (1" tapes get 3 rows, but you'd need wide stakes). Over the few years I've been using them, no label has ever decayed, fallen off or become unreadable. And they are removable (though not reusable) if you apply the label to a pot.