I've been cleaning out corners of my house, and ran across a list of authors for those who are interested in mysteries and gardens. I'm sorry to say, I don't recognize any of the names on this list so I can't make further recommendations.
Susan Wittig Albert
Anthony Eglin
Janis Harrison
Joyce & Jim Lavene
Anne Ripley
John Sherwood
Michelle Wan
Please comment if you've read (and can recommend) any of these authors.
Happy reading!