|Vigorous, popular, long-lived, woody-based perennial reaching 4 to 5 feet tall. Valued for its showy white, semi-double 4 inch flowers with broad white tepals and shaded green underneath. Blooms from summer to fall. Does well in partial shade. Plants in areas with harsh winters will benefit from a fall mulching. Staking may also be necessary, especially to keep plants upright after a rain. Divide in fall or early spring. Contact with sap may irritate skin. Sometimes referred to as 'White Giant' or 'White Queen.' Slow to establish, but then spreads rapidly.