Pick by what the year was
A hard year: lilies and lotus, quiet and steady. A good year: rose and peony, full. A year apart: orchid and camellia. A first anniversary: a single rose, and let the note carry the rest.
You do not need a large bunch. One well-chosen stem with an honest message beats nine stems and “happy anniversary”.
How to write the note
Name one thing from the year. A trip, a hospital waiting room, the night the boiler broke, the thing you both still laugh about. Then say what you noticed about them in it.
“You handled the move better than I did and never said so” is an anniversary message. “Another year, still my favourite person” is a caption.
If you forgot
Send it the moment you remember, with the truth in it. A bouquet at 11pm on the right day, or the next morning with an honest line, is recoverable. A florist cannot do that for you; a link can.