If for any reason the terminal bud is lost - such as just a one time temperature drop below minus ten degrees during the winter or it gets broken - cut off, the oak leaf hydrangea will not bloom the following ssummer. In addition the plant likes the following growing conditions for est blooming: moist, fertile, well-drained soil, sun to partial shade - not full time shade such as the north side of a house, mulch to maintain a cool moist root zone.