SignificancePollen viability depends on a tough external barrier called the pollen wall. Pollen wall components are produced by tapetum cells, which surround developing pollen grains within the anther. Precise coordination of tapetum activity with pollen grain development is required to ensure effective pollen wall formation. Here, we reveal that this is achieved through a multidirectional dialogue involving three distinct cell types. We show that peptide precursors from the tapetum are activated by proteases produced stage specifically in developing pollen grains. Unexpectedly, we found that activated peptides are perceived not in the tapetum, but in the middle layer, which encloses the developing tapetum and pollen grains, revealing an unsuspected role for this enigmatic cell layer in the control of tapetum development.