A horticultural lighting apparatus for illuminating a plant comprises a lighting module with multiple lighting elements. The lighting module is restricted to operating in a plurality of discrete modes which emit light with different discrete spectral compositions, by emitting light from the lighting elements in different predetermined combinations. These modes comprise a growth mode configured with a spectrum that promotes growth of the plant, and at least one steering mode configured with a spectrum that steers another biological process of the plant, wherein at least one of the lighting elements is arranged to emit in both the growth and steering modes. The apparatus further comprises a controller arranged to switch the lighting module between the plurality of discrete modes.
