I’m about to buy my first grow tent. What sort of lighting system is best? And how many lights do I actually need?

High intensity discharge lights, including metal halide and high pressure sodium, are still the most commonly used lighting systems in grow tents. However, many growers have been turning to fluorescents or LEDs with great success.

Although grow tents differ from a typical growroom in a few ways, the same basic principles for lighting requirements still apply. If you are using HID or fluorescents, you should provide around 40W of lighting per square foot of garden space.

For example, let’s say the grow tent has a 4- by 4-foot floor space that will be filled with plants. This equates to a 16 square foot growing area. For this size, you could use a 600W light to provide 37.5W per square foot. If cooling the grow tent is not an issue, you could opt for a 1,000W system, which would provide 62.5W per square foot. Yet another option would be using two 400W lighting systems for a total of 800W, or 50W per square foot.

For increasing growth rates and yields, more light energy is always better, but higher-wattage systems enclosed in a grow tent can cause serious heat issues. This is the reason why many people are turning to LEDs, which generally operate at cooler temperatures than HIDs or fluorescents.

Just be sure to closely compare LED lighting systems before making a final decision, and find a system that produces an equivalent photosynthentically active radiation (PAR) output to that of a 600W or 1,000W HID lighting system. The LED system that produces the most PAR per watt consumed will be the most efficient choice.