Hardiness: to Zone 4. 'Center Star' is a non-vining plant that provides significant color to the perennial garden. The upfacing blue flowers blanket the plant for a period of two months beginning in early summer. 'Center Star' retains its dark green glossy foliage throughout the growing season. To retain an upright form, stems may need support. Whether adding a burst of blue in the perennial garden or hanging over a retaining wall, 'Center Star' is a significant addition to any landscape. Plants grow to 30"-36".