Bioenergy sorghum is a highly productive drought tolerant C4 grass that accumulates 80% of its harvestable biomass in ~4 m length stems. Stem internode growth is regulated by development, shading, and hormones that modulate cell proliferation in intercalary meristems (IMs). In this study, sorghum stem IMs were localized above the pulvinus at the base of elongating internodes using MRI, microscopy, and transcriptome analysis. A change in cell morphology/organization occurred at the junction between the pulvinus and internode where LATERAL ORGAN BOUNDARIES (SbLOB), a boundary layer gene, was expressed. Inactivation of an AGCVIII kinase in DDYM (dw2) resulted in decreased SbLOB expression, disrupted IM localization and reduced internode cell proliferation. Transcriptome analysis identified ~1,000 genes involved in cell proliferation, hormone signaling and other functions selectively up-regulated in the IM compared to a non-meristematic stem tissue. This cohort of genes is expressed in apical dome stem tissues prior to localization of the IM at the base of elongating internodes. Gene regulatory network analysis identified connections between genes involved in hormone-signaling and cell proliferation. The results indicate that gibberellic acid induces accumulation of growth regulatory factors (GRFs) known to interact with ANGUSTIFOLIA (SbAN3), a master regulator of cell proliferation. GRF:AN3 was predicted to induce SbARF3/ETT expression and regulate SbAN3 expression in an auxin dependent manner. GRFs and ARFs regulate genes involved in cytokinin- and brassinosteroid signaling and cell proliferation. The results provide a molecular framework for understanding how hormone signaling regulates the expression of genes involved in cell proliferation in the stem IM.