The amount of light fixtures you need depends on the size of your grow area and your target light output (PPFD). Your target light output will depend on the type of crop you are growing, which you can find below and in our article How Much Light Does My Indoor Plant Need?
The Amount of Light Required To Grow Different Types of Indoor Plants
The size of your grow area will affect how many light fixtures are needed to obtain your target PPFD. Since low-light plants and vegetables do not require as much light, one VOLT Grow® dimmable 440W VL-1 LED Grow Light will be sufficient in anywhere from a 2’x3’ to a 6’x6’ space. In a 6’x6’ space, you can still get an average PPFD of 379 µmol/s/m2.
High-light plants like this require significantly more light, and you will want to use a VOLT Grow® 440W VL-1 in a smaller area or the 720W FL-1 LED Grow Light in a larger space.
For the vegetative stage, the target PPFD is lower at 400-600 µmol/s/m2. After choosing which type of light and how many to use, you should follow the flowering PPFD recommendations. Then dim the LED grow lights to lower light output for the vegetative stage. For the flowering stage, most growers target a PPFD of 1000 µmol/s/m2.
Generally, you want one FL-1 per 4’x4’ or 5’x5’ area or one VL-1 per 3’x3’ or 4’x4’ area.
Check out how many lights you would need depending on the different size areas if you are growing full-cycle. There are different recommendations for beginner versus advanced growers because once you reach an extremely high light output (average PPFD of 1000 or greater), proper CO2 and ventilation are required. If it is not implemented correctly, too much light can be harmful to the plants.
If you have a commercial facility or are growing in a larger size area, get a grow lighting consultation from one of our experts that includes a lighting design layout plan.
How Far Should LED Grow Lights Be From The Plants?
A common misconception about LEDs is the hanging height. The placement of LED grow light fixtures can be as close as 6 inches above the canopy. However, HPS lights give off a lot of heat and must be hung far away from the canopy to avoid burning the plants. Before buying grow lights compare the operations cost difference between LEDs and HPS.
LED lights are much more energy-efficient and produce significantly less heat than HPS lights. This advantage allows LED grow lights to hang closer to the plants to get a higher PPFD without causing damage.
Avoid hanging LEDs higher than 18-24 inches above the plant’s canopy. The light density significantly decreases as the light dissipates before reaching the plants. Aim to hang the LED lights around 10-12 inches above the canopy. You can get as close as 6 inches to maximize PPFD (if you have proper CO2 and ventilation).
It is important to monitor your plants and see how they react when increasing light intensity. Lower or raise the height of the LED grow light as needed to avoid any stress on your plants.