Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendrite trees that partly share common features. A large apical dendrite elongating from the apex of the cell body is formed in both cell types, while minor basal dendrites emerging from the opposite side of the cell body are developed only in pyramidal cells. We evaluated the qualitative and quantitative differences in dendrite arborization of pyramidal cells and granule cells in dissociated hippocampal culture. Pyramidal cells and granule cells showed similar asymmetric dendrite patterns in vitro, although they are different in size. Pyramidal cells developed a single large principal dendrite and several minor dendrites, reminiscent of the apical and basal dendrites seen in vivo. Granule cells retained minor dendrites in addition to the large principal dendrite, which are not typically seen in vivo. Time-lapse imaging revealed that the asymmetric growth of a single principal dendrite in young pyramidal cells and granule cells underwent dynamic extension and retraction of multiple dendrites. The principal dendrite was mobile and frequently replaced with other dendrites until it is fixed in the second week in culture. The replacement of the principal dendrite was accompanied by reorientation of the Golgi apparatus and the centrosome. The present study uncovers important similarities and differences in morphology and dynamics of the polarized dendrites in hippocampal principal neurons in dissociated culture.