"Kent is known as the 'Garden of England,' and Sissinghurst Castle does not disappoint," says Strong. "The lawns and terraced colors of wildflowers of the area are a treat to the soul. A stroll around the grounds is tranquil in any weather, but spring and summer are the highlights." Created in the 1930s by Vita Sackville-West and Harold Nicolson, the English garden has a series of "rooms," all featuring different designs and planting strategies. Depending on when you visit, you may get to see daffodils, peonies, magnolia blossoms, or blooming fruit trees. Would you like to see Sissinghurst Castle's English gardens in the spring or summer months?

Billed as "the most beautiful spring garden in the world," Keukenhof is one of the best places to glimpse the colorful tulips commonly associated with the Netherlands. The window to see them is relatively short, though, so you'll need to plan your visit between mid-April to mid-May to experience the peak blooming period. Covering 79 acres, the garden also features roses, hyacinths, daffodils, orchids, lilies, carnations, and irises. Are you interested in visiting Keukenhof when the tulips are in full bloom?