Complete guide for grow light distance from plants for Maximum Yield

The best grow light hanging height

LED grow lights should be hung at 12" or 30cm over the plant canopy for maximum efficiency. Increase to 18" or 45cm to achieve more even spread across the plant canopy. HID grow lights should be hung between 16" or 40cm to 24" or 60cm over the plants, the distance increasing for bigger fixtures of 600 to 1,000 watts.

Adjusting your grow light height for maximum yield

This guide will help you understand how high to hang your grow light for maximum photosynthesis and healthy growth. Whatever your chosen lighting system the principal is the same:

Hang your grow light close to the plants so they receive as much light as possible.

The higher the grow light is above the plants the more light will overshoot the plant canopy and reflect off the grow tent or grow room walls. Not all this light is reflected back due to reflectance losses so some light energy is wasted as heat.

The trick is ensuring the grow light is not too low as to cause plant damage directly under the light fixture, where the light and heat are most intense.

Grow light manufacturers should recommend optimum hanging height and provide a PAR map

The LED grow light manufacturer is best placed to provide information on the optimum hanging height in the specified grow space. A PAR map is a visual aid displaying the PAR intensity measured by a PAR meter (quantum sensor) in a grid across a plane representing the plant canopy.

You can see the PAR intensity measurements across the specified grow area and observe the maximum and minimum PAR intensity and how even the distribution is.

If your grow light does not have a PAR map we have published a list of optimum hanging heights for 70 grow lights tested on the MIGRO Youtube channel. Scroll to the bottom of this article to see the full list separated by grow area.

LED grow light hanging height guide

If a PAR map is not available for your grow light fixture we can guide you on the best hanging height for an LED bar grow light.

LED grow lights are large in physical size and their format spreads light wide and allows a relatively low hanging height. Also LEDs do not emit Infra red or heat radiation, as HPS grow lights do, so you can position LED grow lights closer to plants.

If the distance from the LED grow light to the plants is relatively low at 30cm or 12" more light will reach the plant canopy but the spread will be less uniform. The plants in the centre will receive much higher PAR intensity than the plants at the edges.

Increasing LED grow light hanging height to 45cm or 18" increases the PAR intensity at the edges and improves uniformity but the total amount of PAR reaching the plant canopy.

If you want the compromise between the two use a medium LED grow light hanging distance of about 15" or 38cm.

Recommended hanging heights for all the LED grow lights tested on the MIGRO Youtube channel

Below are Led grow light hanging distance charts for the most popular grow lights in their specified grow area. You can see the optimum hanging height for the majority of grow lights is between 30cm or 12" and 45cm or 18"

2ft x 2ft or 60cm x 60cm LED grow light hanging height chart

3ft x 3ft or 90cm x 90cm LED grow light hanging height chart

4ft x 2ft or 120cm x 60cm LED grow light hanging height chart

4ft x 4ft or 120cm x 120cm LED grow light hanging height chart

5ft x 5ft or 150cm x 150cm LED grow light hanging height chart