Green typically reigns supreme in garden idylls, but today the subtle burgundy hues of barberry bushes and the shadowy violet of hyacinths may take the crown. We’re walking through the grounds of interior designer Alexandra Champalimaud’s home in Litchfield, Connecticut, during one of her favorite times of the year: the fleeting days between spring’s end and the full swing of summer, before clusters of bluebells and delicate Aruncus give way to the showstopping blooms of July.