Not my usual haunt but had a quick look at the gardening stuff when I popped in to do a bit of top up shopping..... ;D as you do!
They had bags of really nice,wide white plant lables in stock, not the cheapest at 96p for 50 (plus a little pencil, unsharpened but hey ho.. :-\) but they are ideal for long term plant labels as you can fit two lines of writing easily on them, something I struggle to do on most labels. Plus whatever they are made of has a slight texture which makes them easy to write on with either pencil or a Sharpie pen. Recommended! ;D