Not an aggressive spreader, but up to 20"/50 cm not unknown. Deadheading suggested for continued bloom, though blooms from mid spread into midsummer, and in some climates into the fall.
Full sun to possibly part sun. Rock gardens, cut flowers, planters, edging.
Try to plant in a location that enjoys partial sun and remember to water moderately. Birch hybrid is generally regarded as a tender plant, so it is really important to plant out well after your last frost date.Birches Hybrid, Birch’s Hybrid