Roughness is an important feature in plasmonics. Nanoparticles with a nanoscale surface buckling or with protrusions out of surfaces display higher absorption efficiencies and surface-enhanced Raman scattering activities with respect to smooth surfaces. In this work the effects of the branches and of their electromagnetic coupling on the near-field enhancement are investigated by considering urchins-like silver nanoparticles. The theoretical analysis here reported, performed in the framework of the discrete dipole approximation, shines light on the optical response of these multibranched objects in the near-field regime by varying the spines dimensions and their relative distances. Three important results are obtained: (i) a too large number of protrusions makes them electromagnetically interacting, thus reducing the field enhancement factors; (ii) increasing of the spines radius blue-shifts the resonances and …