You have probably heard the advice from several professional gardeners about the different stages of plant growth and how each stage requires a dissimilar amount of watering, lighting, grow medium, etc. The germination stage is not too complicated because the basic growing medium and requirements are needed, both for indoor and outdoor gardening. However, the challenge begins during the vegetative stage, especially in indoor gardening, due to the artificial lighting requirements. The vegetative stage occurs after the germination process and before photosynthesis and flowering begin.
According to indoor garden experts, when plants reach 24 inches tall during the vegetative stage, they need more light to propagate growth efficiently. The basic fluorescent lighting cannot provide this transition for the plants anymore so your indoor lighting must get a notch higher. The experts recommend the use of metal halide grow lights for the vegetative stage. Metal halide is a combination of sodium, thallium, indium, scandium, and dysprosium iodides which altogether produces a spectral power distribution and provides color balance. The metal halide is considered a member of high intensity discharge (HID) lamps and produces the blue light spectrum, the most efficient supplemental light to maximize photosynthesis.
However, you must take precautions on wattage configurations and the distance of the grow light from your plants. Be reminded that metal halide produces intense light so you don’t want your plants to suffer from thermal stress. The common wattage configurations for home use indoor gardening are 175W, 250W, and 400W. As for the distance of the grow light from the plant, 8 inches away for 175W, 10 inches away for 250W, and 14-18 inches away for 400W.
Another tip of using metal halide grow lights in your indoor garden, do not be complacent in using grow lights, especially with these metal halide ones, because just like the other types of lamp, there is also a possible risk of lamp explosion due to chemical degradation, thermal stress, or mechanical vibration.
Here are some guidelines to follow for best practice in using grow lights indoors: purchase metal halide grow lights from reputable manufacturers only, regularly inspect your grow light and if it has cracks or discoloration on the bulb then replace the bulb before it reaches the end of its life and assemble lamp fixtures instead of spot re-lamping. By doing these, you do not only protect your plants, but you also protect yourself and your house. Safety first.
Aside from indoor gardening, metal halide lighting is also often used in indoor functions such as concerts and athletic facilities and for reef aquarists due to its high intensity light source.