Control of the radiative properties of emitters such as molecules, quantum dots, and color centers is central to nanophotonic and quantum optical devices, including lasers and single photon sources. Plasmonic cavities and nanoantennas can strongly modify the excitation and decay rates of nearby emitters by altering the local density of states. Here, we demonstrate large enhancements of fluorescence and spontaneous emission rates of molecules embedded in plasmonic nanoantennas with sub-10-nm gap sizes. The nanoantennas consist of colloidally synthesized silver nanocubes coupled to a metallic film which is separated by a ~5 nm self-assembled polyelectrolyte spacer layer with embedded molecules. Each nanocube resembles a nanoscale patch antenna whose plasmon resonance can be changed independent of its local field enhancement. By varying the size of the nanopatch, we tune the plasmonic resonance by ~200 nm throughout the excitation, absorption, and emission spectra of the embedded molecules demonstrating giant fluorescence enhancement for antennas resonant with the excitation wavelength. Next, we directly probe and control the nanoscale photonic environment of the embedded emitters including the local field enhancement, dipole orientation and spatial distribution of emitters. This enables the design and experimental demonstration of Purcell factors ~1,000 while maintaining high quantum efficiency and directional emission. Full-wave simulations incorporating the nanoscale environment accurately predict the experimentally observed emission dynamics and reveal design rules for future devices. Finally, progress on coupling colloidal CdSe/ZnS core-shell quantum dots to the plasmonic nanopatch antennas will be discussed.