Indoor marijuana grow room with plants in soil under lights

How to Increase Your Cannabis Yields by Using a Lux Meter

Cannabis plants require plenty of light in order for them to grow healthily and produce good yields. You can use a lux meter to help you measure and maximize the amount of light that gets into your grow-op in order to boost your yields.

A lux meter is a device that measures the quantity of light (lux=lumens/m²) in the grow room. Compared to PAR meters or Quantum light meters (which are used by professionals) Lux meters are much more affordable. Good PAR meters cost upwards of $1,000 while the price of lux starts from a low as $20.

Advantages of Using a Light Meter

Here are some benefits you have when you use a lux meter:

  • Increased Yields

Having established that light is crucial to growth; you can use a lux meter to determine the best spots in your grow room to grow your cannabis. You can also use the meter to establish the appropriate distance from the lights to your plants. The lux meter can also let you know if the light you’re using is not enough to max out yields.

  • Tells You When It’s Time to Replace HID Grow Lights

Grow lights like MH/HPS bulbs have a limited lifespan and over time they become increasingly dimmer. For this reason, they need to be replaced often. You can rely on the lux meter to let you know when it’s time to replace your bulbs.

  • Prevents Plant Problems

Both insufficient and excess light are bad for cannabis plants as they can cause stress on the plants and result in issues like bleaching and light burn. The lux meter will help you determine the right amount of lighting needed to ensure your plants are healthy throughout all stages.

How Much Light Do Cannabis Plants Need?

Light requirements vary depending on the phase of the growth cycle. For example, seedlings don’t need a lot of light. However, once a plant gets into the veg phase, it needs a lot of light and the same applies during the flowering phase. The flowering phase actually requires a lot more light for the buds to become really big.

So, how much light is sufficient?

  • 5,000 – 7,000 lux for clones and seedlings
  • 15,000 – 50,000 lux for vegetative growth
  • 45,000 – 65,000 lux for flowering

The maximum amount of light recommended is 75,000 lux and anything higher than this will lead to diminished returns. Some strains of cannabis will actually show signs of light stress at 75,000 while bleaching may occur at over 80,000 lux. It’s highly recommended that the light is maintained at or below 75,000 lux.

LED Lights

Lux meters work with most but not all types of lights. White LED lights (COB LEDs) and other “white” lights such as CFL and HID do well with lux meters. However, lux meters are incompatible with “purple” LED lights since these lights radiate purple light. A grower using these types of lights will have to depend on the manufacturer’s information regarding the quantity of light that the products emit. Alternatively, the grower can look for light meters that work with purple LED lights, keeping in mind that these light meters cost more.

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