Vibrant purple flowers 5 inches across open on Siberian iris (Iris sibirica) in early summer. Siberian iris is carefree, growing in full sun to part shade. Leaves add a medium texture to the garden and look good all through the growing season. Siberian iris opens flowers in many shades, including blue, purple, gold, burgundy, pink and white. This iris needs moist soil to thrive, especially when planted in full sun. It’s known as the go-to iris for Southern gardens. Plants grow 34 inches tall by 18 to 24 inches wide. Hardy in Zones 3-9.