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PPF, DLI & the Grow Sensor
Daily Light Integral (DLI) and Photosynthetic Photon Flux (PPF).
Why are they important? How do they relate to each other? How do they affect yield and the quality of your product?
As always, at the end of the post, you’ll find some interesting links to articles that could help you learn more about these essential topics.
Usually, growers learn about PPF before DLI, as you need to be able to measure PPF to figure out your DLI, so let's do the same.
PPF and PPFD both relate to plant lighting, but they measure different things.
PPF tells us the total amount of light produced by a light source per second. It counts all the photons in the spectrum used for photosynthesis without considering the area they reach.
On the other hand, PPFD measures how much of that light actually lands on a specific area (like in a grow tent) in one second.
PPFD is about the concentration of light in a given area, showing how much light a plant is exposed to in its growing environment.
So, while PPF is about the total light output, PPFD is about how much light is available to plants in a specific spot.
Got that? Good!
But why are either of these values useful to growers?
Essentially, cannabis can only use a certain amount of light to grow per day, and that amount of light differs depending on the stage of growth and the environment.
If you're not measuring your PPF or your PPFD, you won’t know how much light your plants are receiving.
Is it too little or too much? Who knows!?
If you have too little PPF(D), you will get slow, weak, and stretchy growth.
Too much PPF(D) will cause burnt, bleached plants, stunted growth and nutrient deficiencies. On a side not excess PPF(D) usually goes hand in hand with excessive heat and a lack of terpenes in your final product.
Those are all big problems, and that's not all...
If you give your plants more light than they need for their stage of growth and environment, you're basically wasting electricity.
Larger bills for no gains!
In the perfect environment, cannabis can use A LOT of light, equalling a higher DLI, and the results are impressive.
But you have to have your grow dialled in for it to be of any real use.
In this post, we go into great detail about how to measure your PPF(D) and how much you need for your situation.
Here's a great graph that shows how PPF(D) affects your yield.
But how does DLI fit into this equation, and why is it useful to growers like you?
Daily Light Integral, or DLI, is all about the big picture of light exposure for plants.
While PPFD measures the instant amount of light, DLI sums up the total amount of light a plant receives in a day.
It's measured in moles of light per square meter per day.
DLI is crucial for understanding how different plants thrive. Some plants/strains need lots of light, while others do well with a little less.
DLI guides us in providing the right 'dose' of light for healthy plant growth.
Cannabis can only use so much light per day.
Have you ever gone into your grow space towards the end of the day and noticed that the plants look droopy and sad?
This is a natural response. Put simply; the plants have gone to sleep as they have received all the light they can sensibly use in that day.
This is a strong signal that the amount of light they receive a day (DLI) is too much! This is either driven by genetic potential or by an imballance with your grow room. For example your pushing every element of your grow space for high DLI growth:
- But not supplementing with Co2,
- or have a very low VPD.
This is wasted energy, meaning higher electricity usage for no gains. Your lights are on, but your plants are not at home!
In this guide, we provide some great baselines for how much DLI your plants need for your situation.
We also go into great detail about DLI here.
How does the Grow Sensor measures both DLI and PPF?
Spoiler alert: It measures both and measures them 24/7!
We’ve talked about why they are essential if you want to Grow The Best, how to measure both, and the differences measuring them can make on your yield and the quality of your product.
There’s never one magic change you can make to grow the best cannabis; it’s a careful balance of many factors mixed together: DLI, PFF, LST, VPD, temperature, humidity, etc. that all make up your environment.
All of these subtly affect the outcome of your grow.
This arrangement of conditions basically makes your unique style as a grower - which is pretty cool!
One key reason we are learning about factors like PPF and DLI is that they help us achieve more repeatable results with every round we grow.
Surprisingly, this isn't easy to achieve - it’s one of the reasons growers keep coming back for more; we are chasing perfection every time - we want to Grow The Best!
Have you ever grown the same cutting twice with different results? That's because one of these many factors was not repeated the same way.
Sounds simple, doesn't it?
It isn't.
But that's where the Grow Sensor helps! Data is king.
When it comes to DLI and PPF, the Grow sensor measures both continually 24/7.
That means you can see your PPF any time you want throughout your grow, and you can also see how your DLI accumulates over a day.
Meaning if you're using too much or too little light, you can see instantly!
You can also set a limit and alert for when your ideal DLI for the day has been reached. I can’t begin to tell you how useful this is for dialling in your grow.
I can give my plants the exact amount of light they need and measure the results.
In addition, you can set lights-off alerts if your lights turn off during the day and lights-on alerts if they turn on at night.
Just set your photoperiod in the app, then set your PFF limits, and you're done!
If there's a problem, you'll get a push notification to your phone.
All this leads to happier, healthier plants.
And you'll be using the right amount of electricity for your situation. That equals savings!
Data is king!
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