Cape Cod Boys Siberian Iris thrives in full sun to partial shade and prefers consistently moist, well-drained soil. Water regularly, especially during dry spells, to maintain soil moisture. Fertilize in early spring with a balanced fertilizer to encourage vibrant blooms. After flowering, remove spent blooms and cut back foliage in late fall to tidy the plant. Divide clumps every 3-4 years to prevent overcrowding and promote healthy growth.