This grower is fairly sure of this plant identification.
Hydrangea anomala var. petiolaris (Climbing hydrangea). This is a climbing plant which will produce white flowers. It needs moist soil.
They are fully to frost hardy and will prefer sun or semi-shade with fertile, moist but well-drained soil. They will require more shade in dry areas; provide shelter from cold, drying winds. Some hydrangeas become chloritic in shallow chalk soil.
Ornamental, climbing, dried arrangements
Italics = data drawn from parent genus or speciesView Full Plant Finder Record