How Big are Grow Lights?


Grow lights are used in the indoor growing of plants in grow rooms and nurseries. The size of these lights and their lumen output capacity are the most essential aspects of lighting for all indoor growers. Grow light size varies through different wattage, lumens and spectrum production.

Types of Grow Lights

Traditional grow lights are known as HID lights. These lights produce a high energy consuming quality of pseudo sunlight for indoor plants. These lights are expensive and though they offer an ample source of quality light, they also create an enormous strain on energy use. LED grow lights use 80 percent less energy than HID lights and produce the same spectrum and amount of light for plants to flourish indoors. These grow lights are manufactured in various sizes to suit the crops grown indoors and the size of the grow room.

Light Spectrum

Indoor plant growth is dependent on multiple spectrums of light to grow properly: a blue spectrum for plant stem and foliage production, an orange spectrum for fruit plants to produce fruit and a red spectrum for the flowering of plants. LED lights produce this spectrum at half the cost and energy consumption of HID lighting systems.

Grow Light Size

The size of the grow light will determine the power capacity or amount of lumens that the light produces. The sun gives off an amount of light that can be simulated using a light that produces 1,000 lumens. Common lumen rates in grow lights are 400, 600 and 1,000. A standard fluorescent grow light is between 24 and 54 watts and produces 2,000 to 5,000 lumens. These are used in large grow rooms with adequate ventilation to reduce the heat from this output of light energy.

Light Placement

Light placement regarding a standard grow light size producing about 1,000 lumens is 12 to 19 inches above the plant. Continuous measurement of the plant and movement of the light is essential for light systems that produce more than 1,000 lumens or for lights with little ventilation. With air-cooled lighting systems, the plants can safely grow right up to the light bulb, though this is not recommended by most indoor growers unless using fluorescent lighting, which is cool to the touch.

Timing of Lighting Hours

Light timing is restricted in accordance to the normal behavior of the sun. Plants at most need 12 to 18 hours of light per day to grow efficiently. During the early growth stages the lights should be set to mimic the springtime with shorter light hours and gradually extending the time as you simulate a transition into summer with longer light hours. Timing is also increased with flowering and fruit bearing plants. The increase in light will propagate the plant into producing fruit and flowers at a faster rate.


  • 1-Hydroponics: Grow Lights
  • Lights Grow: Grow Lights
  • Home Harvest: Lighting
Keywords: how big are grow lights, size importance of grow lights, grow light size variation

About this Author

Jeremiah Blanchard has been writing professionally for the past five years, specializing in nature, environment, conservation and travel. His work has appeared in activist columns on and Blanchard has studied photography at William Carey College and has a Bachelor of Arts in history from the University of Southern Mississippi.

Article provided by eHow Home & Garden | How Big are Grow Lights?