A new and distinct cultivar of Hydrangea plant named ‘；COF-HM2’； is disclosed, characterized by vigorously growing, compact plants with strong, upright peduncles. Inflorescences are dense mophead with uniquely colored sepals beginning maturing green-purple and maturing pink. Sepals are extremely thick and persist in good condition up to 8 weeks. Fall foliage is a deep red. The new variety is a Hydrangea, normally produced as an ornamental plant.
