The number of growth flushes per growing season, the length of rest periods between flushes, and the relationship between shoot and root growth were evaluated in oak seedlings (Quercus alba, Q. marilandica), trees (Q. alba), and stump sprouts (Q. alba, Q. velutina). In both seedlings and trees, root growth was reduced during shoot growth. Under constant environmental conditions, seedlings underwent a series of very synchronous flushes of leaf and shoot growth and these flushes were separated by distinctive rest periods. It was only while leaves and shoots were not growing that root growth occurred to any appreciable extent. Under field conditions, flushes of growth were still observed in stump sprouts, but were no longer synchronous. In understory seedlings and in large trees, only one flush was observed. Forest Sci. 26:590-598.