I used to think Valentine’s Day was invented to trick guys into buying cheesy cards. But then, six months ago, I got married. Now I’ve decided to blow her mind (and my paycheck) on a headboard-busting floral arrangement. I began my hunt at Posy, a snug, second-story shop on the Upper East Side. The owners, Paula and Stamos, offered me a domelike bouquet made up of three types of roses: deep-scarlet “cherry loves,” burgundy “black beauties,” and small, fuchsia “sexy ladies.” It was clearly worth the price tag—the flowers were expertly chosen and the construction was simple, precise, and gorgeous. But my own “sexy lady” deserves something with more personality. 145 E. 72nd St., nr. Lexington Ave.; 212-744-7788