|Grown for its rose-pink, semi-double flowers, 2 1/2 to 3 inches across, that bloom summer to fall. This popular, vigorous, long-lived perennial with a woody base reaches 4 to 5 feet tall. Adds color to partial shade, fall borders. 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. Slow to establish, but then spreads rapidly.