flux weed

How To Use A Lux Meter To Increase Your Cannabis Yields

For healthy growth and good yields, almost nothing is more important than providing your cannabis plants with plenty of light. With an affordable lux meter, you can measure and optimise the amount of light in your grow-op to increase your yields.

If you want to max-out your yields, you need to make sure that your cannabis plants are receiving an adequate amount of light. With a lux meter, this all becomes easier than ever!


A lux meter is a relatively simple device with which you can measure the amount of light (lux=lumens/m²) in your grow room. What makes a lux meter attractive compared to a PAR meter or quantum light meters used by professionals is that it is much cheaper. While a good PAR meter can easily cost €1,000 or more, you can obtain a lux meter for a lot less. Simple lux meters start at €20 and upwards.


Helps Increase Yield

A lux meter can help increase the yield of your cannabis plants—an obvious benefit to growers. With it, you can determine the optimal spots within your grow room, or you can use it to determine the proper distance from your lights to your plants. A light meter/lux meter also lets you know when the light you’re using is simply not enough for maxing out yields.

Tells You When You Need To Replace HID Grow Lights

Some types of grow lights, such as MH/HPS bulbs, have a limited lifespan. In due time, they get increasingly dimmer, and this is why they need to be replaced at certain intervals. The light meter can reliably let you know when you need to replace your MH/HPS bulbs.

Prevents Some Plant Problems

Both insufficient light and too much light can be bad for your cannabis plants. The light meter can help you ensure healthy plant growth throughout all stages. The proper amount of light, not too much and not too little, will reduce stress on your plants, preventing further issues like light burn and bleaching.


How much light your plants need will vary based on each phase of the grow cycle. Seedlings can’t take a lot of light, but once a plant is in veg, it needs just about all the light it can get. This allows plants to grow vigorously to their full potential. The same goes for flowering. Although plants in bloom thrive under a different spectrum of light than during veg, they still need a lot of light exposure to make sure the buds are as big as they can be.


  • Clones and seedlings: 5,000–7,000 lux
  • Vegetative growth: 15,000–50,000 lux
  • Flowering: 45,000–65,000 lux
  • Maximum recommended amount of light: 75,000 lux

What about even more light? At some point, increasing the light beyond a threshold plant can manage will actually diminish returns. Said differently, once you reach about 85,000 lux, it’s simply too much. Some strains may already show signs of light stress at only 75,000 lux, with the risk of light bleaching increasing at over 80,000 lux. To keep it safe, it is best to stay at or below 75,000 lux.


When you use a lux meter to measure the amount of light in your grow room, make sure you measure at the height of your plants’ canopy. This allows you to determine how much light they’re actually receiving. Even if the distribution of light across your growing area may appear even, you should take a number of measurements in different spots of the grow room. This is how you can find blind spots or optimal spots that are not always obvious to the unaided eye. When you locate these spots, you can rearrange your plants accordingly for best results.


A lux meter works with all types of “white” lights, which includes HID, CFL, and white LEDs (COB LEDs). However, it doesn’t work with “purple” LED lights, which emit a purple light due to their combination of blue and red LEDs. Unfortunately, most cheaper LED lights are these purple types. So, if you use one of these for growing, you would have to rely on manufacturer information about how much light the product really emits. Alternatively, you could obtain a light meter that can be used with these types of LEDs. But be aware that these often cost a lot more.

With a lux meter, you can measure and optimise the amount of light your cannabis plants receive, which helps to boost final yield.

What is the Cannabis “Fluxing” Technique?

by Nebula Haze (article created with permission from Light Addict)

I recently joined Instagram and I saw that there are many growers who use an eye-catching cannabis growing technique that’s been named “fluxing.” A little research shows that the fluxing technique was developed by a grower by the name of Light Addict. Here is the original fluxing tutorial from 2014: Light Addict’s Quick Guide to Fluxing (original fluxing guide by the creator).

Light Addict has also published a book on the topic which is more detailed and includes many fluxing tips and tricks, as well as a bonus guide to successful cannabis grafting. This is fluxing!

This grid-like base of a “fluxed” plant will develop into a mass of buds like this!

Light Addict explains the step-by-step process in detail with tons of pictures, so there is no need to re-create the tutorial, but I just wanted to share this technique with growers who may not have heard about it before, and offer a quick overview.

The process is similar to manifolding in that it sets up a plant with a split at the base between two main stems. However, the steps differ after that and the resulting base looks very different!

Fluxing starts with a similar structure to manifolding. This is an example of a plant after the first step of being manifolded.

Fluxing involves spreading the two main stems out, to produce a wide and flat plant with lots of bud sites that are evenly spaced.

Examples of cannabis fluxing (all pictures by Light Addict)

A benefit of fluxing over manifolding is that it gives you complete control over the growth pattern of the plant. Every single site will have equal spacing for light penetration and airflow. Plus, every single limb has the same structure. This can be a great advantage! As Light Addict puts it, “The process is almost symbiotic in veg as you control every facet of its growing.”

The main idea of fluxing is to top the marijuana plant when it is young and r emove extra growth besides two main stems, then s ecure the two main branches down as the plant grows. Further topping is used to create a grid-like manifold where every cola is evenly spaced.

Master “fluxers” often secure plants very low to help keep plants short and tidy, but for new growers, it can be easier to secure your two main stems more loosely and let plant grow relatively naturally after that. This is also a good choice for growing auto-flowering strains, as they have less time to recover in the vegetative stage from extensive topping and training.

However you choose to do fluxing, you gain the ability to create cannabis plants with many colas that are evenly spaced!

Check out Light Addict’s Quick Guide to Fluxing or the official book for detailed instructions including every little tip and trick, as well as a bonus guide to successful cannabis grafting!

To "flux" cannabis means to build a grid-like manifold at the base of the plant. This creates many big colas and can help maximize yields from a grow light!