The LED grow light fixture uses a densely-packed array of high-brightness LEDs that are not individually packaged where the array behaves similarly to a point source of light. The extended point source LED array, with its lens and associated reflector, result in a concentrated, partially-collimated light source, such that the intensity of the light does not diminish rapidly as distance from the light source increases. The LED array contains a plurality of LED strings that may be separately controlled, thereby allowing the spectral content of the LED grow light to be varied, to facilitate desired plant growth at various stages of plant life. The light emitted at each of the multiple different wavelengths from the array is evenly distributed, when the objects being illuminated by the array are at a distance of less than about 6 feet or even less than 1 foot from the array.