When The Devil Wears Prada’s Miranda Priestly issued her withering fashion world put-down: “Florals? For spring? Groundbreaking,” she intimated that the seasonal taking-up of florals is, well, less than imaginative. But this annual ritual is not to be sneered at—it’s what we do. Who can resist those early blooms: the first snowdrops and the first daffodils, pushing up through hard ground, bursting forth with the desire to exist once again after a long winter. Clothing contains the same promise.

A fluid midi dress in a wildflower print is a one-way ticket out of the relentless confines of outerwear and central heating, finally. This feeling runs back to the Romans. At Floralia—the spring festival in honor of Flora, goddess of flowers and fertility—white robes were eschewed ...