This grower is sure of this plant identification.
variety is 'Pulmila' height to 1.5m
Giant pampas grass
Cortaderia selloana (Giant pampas grass). An upright dense clumped ornamental grass. It has large feathery plumes of snowy white flowering panicles which will appear in late summer and will last into the winter.
You can prune back in the early spring.
Border, dried arrangements, cutting bed, foliage, ornamental. Autumn interest.