  There is now strong theoretical evidence that a wide range of frustrated
magnets should support quantum spin-nematic order in applied magnetic field.
Nonetheless, the fact that spin-nematic order does not break time-reversal
symmetry makes it very difficult to detect in experiment. In this article, we
continue the theme begun in [Phys. Rev. B 88, 184430 (2013)], of exploring how
spin-nematic order reveals itself in the spectrum of spin excitations. Building
on an earlier analysis of inelastic neutron scattering [Phys. Rev. B 91, 174402
(2015)], we show how the NMR 1/T_1 relaxation rate could be used to identify a
spin-nematic state. We emphasise the characteristic, universal features of
1/T_1, using a symmetry-based description of the spin-nematic order parameter
and its fluctuations.Turning to the specific case of spin-1/2 frustrated
ferromagnets, we show that the signal from competing spin-wave excitations can
be suppressed through a judicious choice of nuclear site and field direction.
As a worked example, we show how P NMR in the square-lattice frustrated
ferromagnet BaCdVO(PO_4)_2 is sensitive to spin-nematic order.
