This grower is sure of this plant identification.
Flowers are slightly deeper purple colour than in photo. In a 38cm diameter bell pot (terracotta colour plastic)
Columbine meadow rue, Greater meadow rue, Meadow rue
Thalictrum aquilegifolium (Columbine meadow rue). This is a very attractive deciduous branched, upright perennial clump. The leaves are a very distinctive blue-green and deeply lobed and the purple-pink flowers are fluffy and pom-pom like. You should grow in rich, moist soil with a sunny or partially shaded spot. You won't need to divide for 4 to 5 years and only then if it is required for propagation.
You can grow them in sun or partial-shade in any well-drained soil. This perennial will need constant moisture and protection from strong winds.
Border, wildflower/meadow, foliage. garden plants. Spring/summer interest.