Introduced in 2006 was Iris sibirica ‘Mistress Moon,’ a glowing Siberian iris with shades of yellow, white and purple in an unearthly glow. This hybrid is considered a midseason bloomer, with the flowers opening in mid-June at Rogers Farm in Stillwater. Iris sibirica is one of the easiest flowers to grow, especially in Maine. Siberian iris are mostly carefree, with their swordlike foliage topped by elegant flowers in late spring and early summer. ‘Mistress Moon’ should reach about 29 inches in height. Siberian iris, which are native to Europe and northern Asia, are often hardy to Zone 3 and can tolerate full to sun to partial shade and still thrive. Give them well-drained but moist soil and the plants will spread fairly quickly over time.