Size: Supplied in a 14cm pot at approx 20-30cm. Hydrangea plant: Get a Hydrangea Double Dutch Alkmaar, Edam or Gouda plant. Hydrangea Double Dutch Gouda: Gloriously creamy-white double-headed flowers! Hydrangea Double Dutch Alkmaar: Boasts beautiful blue double flower heads, great on a patio! Maximum height: Height: Up to 120cm (47") when fully established Spread: Up to 120cm (47"). Hydrangea Double Dutch Edam: Eye catching masses of beautiful pink flowers. Hydrangea Plant | Blue | Living Social