A metal halide discharge lamp for use in plant growing is disclosed. The lamp of the present invention includes an outer envelope having an inner surface, the inner surface including thereon a phosphor layer, the phosphor being selected to convert ultraviolet wavelength radiation into radiation having a wavelength from about 710 to about 780 nanometers; and a silica quartz shaped arc tube with central part being expanded including therein a pair of spaced electrodes and a chemical fill, the chemical fill comprising mercury, an inert gas, indium halide, lithium halide, sodium halide, and cesium halide. A preferred phosphor comprises iron-doped lithium aluminate. A most preferred chemical fill includes indium iodide, lithium iodide, sodium iodide, and cesium iodide in a molar ratio 0.6 to 7.4 to 1.3 to 0.4, respectively, mercury, and an inert gas.