Along Came Tess by Sandra Sookoo

Life can either snake around you with a strangle hold or produce the most exquisite flowers…
At the advanced age of six and thirty, Mr. Jameson Ridley has become content with what he wants out of life. After spending years in India studying the care and cultivation of tea, he became a botanist who specializes in flowers and vines. When he’s invited to his best friend’s estate in the Irish countryside, he accepts with alacrity, for the opportunity to catalogue the flora there can’t be missed.

Along comes Miss Tess Cosgrove. She’s the younger sister of his best friend, and she has the power to send his world tip over tail in every way imaginable… if she weren’t so maddening. Though she was a Diamond of the First Water during her Come Out year, fate has disappointed her so much that she’s given up on London and the ton. As a result, she wants to garden for the rest of her life, to teach others how it is to learn herbal knowledge even though such work is frowned upon in society.