Choosing the right height to hang your LED grow lights isn't straightforward. Even though manufacturers will give you a "general guide" for hanging LEDs, you have to consider many factors before making a decision. Most notably, you must determine how your hanging height will affect your LED grow light's intensity.

As you review our strategies to determine your grow light's height, please never forget the central goal: Provide optimal light penetration withoutburning your plants. While it may be tedious to tinker with your LED grow light's height and intensity, these efforts will pay off with healthy and bountiful buds.


 

Before Hanging An LED, Consider The Perfect PPFD

The first step to figuring out your LED grow light's hanging height is to review Plants' preferred light intensity. Most significantly, you need to check the photosynthetic photon flux density (PPFD).

The ideal amount of PPFD for plants depends on their stage of development. For quick reference, here are the recommended PPFD ranges for plants:

  • Seedling: 100 - 300 μmol/m2/s
  • Vegetative: 400 - 600 μmol/m2/s
  • Flowering: 800 - 1,000 μmol/m2/s

Take a look at the estimated numbers at different heights on your manufacturer’s PPFD maps. You could add these scores and divide them by the number of ranges you collected to get an average PPFD.

Just be sure the central PPFD estimates don't exceed 2,000 μmol/m2/s.

 

Side Note: Does CO2 Exposure Alter The Ideal Height For LED Lights?

Since we just mentioned CO2 supplementation, it's worth noting both the PPFD and DLI scores should be higher with extra CO2 exposure. When you give your plants more CO2, they can handle more intense light and heat. If you don't ramp up the light intensity in your space, you won't be enjoying the benefits CO2 provides.

From a height perspective, you could hang your grow lights lower to increase PPFD scores. Some plant cultivators who use CO2 supplementation say it's OK to start as close as 16" with grow lights and even move as close as 8". At max, most plant strains could benefit from ~ 2,100 PPFD.


 

So, What Are The Height Recommendations For Non-Dimmable LED Grow Lights?

The perfect height for your LED grow light is dependent on multiple factors, including the light's average intensity and your plant's maturity, as well as the temperature of the plant leaves.

Thus, the LED grow light hanging distances for a non-dimmable LED are as follows:

  • Hang your LED grow lights between 20" - 30" above seedlings.
  • As your plants reach vegetative growth, move your LEDs down to about 18".
  • To improve production, try lowering LEDs to 16" during flowering.

Please use these height suggestions as a general guideline. The intensity of your LED grow light may alter how close you can position these diodes to your plants. And make sure the Plants leaf temperature is below 30 Degree Celsius.

Look at the LED manufacturer's recommended heights for the best advice when setting up your grow room. If possible, you should also test your LED grow light with a PPFD scanner so you can calculate the average PPFD your plants will receive throughout your space.


 

Will Hanging Heights Differ For Dimmable LED Grow Lights?

LED grow lights with a dimmer have more leeway than non-dimmable LEDs. Since growers could adjust the light intensity with the flick of a switch, you could fix your light’s hanging height and save more electricity bills. While you switch energy and save electricity, you don't have to compromise on intensity and quality.

Dimmers are particularly useful during the seedling and vegetative stages. During these early stages of growth, plants are more sensitive to lightwaves than during flowering. By contrast, the full intensity of Mars Hydro's LEDs helps stimulate extra production once plant buds emerge.

Here's a general LED hanging height guide for dimmable LED grow lights for the first time:

  • Hang your LED grow lights at 18" - 24" at 25 percent intensity for seedlings.
  • Bring your LEDs to about 18" during vegetation and set the dimmer to 50 percent.
  • Keep your LEDs at 18" and turn them to full intensity.

 

What Does Mars Hydro Recommend For Its Dimmable LED Grow Lights?

If you're using a Mars Hydro dimmable LED grow light, the first thing you need to know is that the percentage on your dimmer corresponds to the max PPFD. For example, if you put your LED grow light at 50 percent, the total PPFD score will be 50 percent. Please factor this into your PPFD and DLI calculations at different stages of growth.

For people who use Mars Hydro's TS, FC, or FC-E models, we'd suggest placing them ~ 5" higher than the recommended height. This extra space will prevent the risk of burning your seedling as you experiment with the ideal PPFD. You could move these lights down to as close as 12" during flowering as long as your leaves can resist.

People with a Mars Hydro SP Series LED grow light should start at 20" and only work down to 16" by flowering.

We'd encourage growers to stick to the following dimmer settings for different stages of development:

  • Seedling to pre-veg: 25 - 50 percent
  • Vegetation to pre-flowering: 50 - 75 percent
  • Full flowering: 100 percent

 

In conclusion, here we’d offer the Mars Hydro LED Grow Light Distance Chart and Dimmer Setting Chart.

  • Most Mars Hydro LEDs

the hanging distance for mars hydro dimmable led grow lights

  • Exception 1: Non-dimmable Mars LEDs

the hanging heights for mars hydro ts600 and sp150

  • Exception 2: Extreme Penetration

the hanging height and dimming for mars hydro sp6500

 

Why Dimmable Mars Hydro LEDs Are Always Worth It!

You could argue that dimmers aren't "necessary" in LED grow lights. However, once you try a dimmable Mars Hydro LED grow light, you'll be amazed at how much time, money, and aggravation this feature saves you. A dimmer will provide customizable light penetration andpull less energy to save electric bills. 

To learn more about why Mars Hydro's dimmable LEDs are worth your money, read through this previous blog.