How to Use Photone

A summary of everything you need to know for optimal lighting

Photone helps you to achieve optimal lighting for your plants. This guide summarizes everything you need to know.

What Is Optimal Lighting

Optimal plant lighting means that your plants receive the right kind of light (PAR), with the right intensity (PPFD), for the right duration (photoperiod), and the right amount (DLI) of it. Ideally, you provide all of these factors at an optimal level where it’s not too much and not too little. Doing so allows your plants to grow tall and healthy whilst also using just the amount of electricity needed and not more.

The Right Kind of Light

Plants use and perceive light differently than humans. To measure the light your plants use for photosynthesis, you must measure photosynthetically active radiation (PAR) using the PAR meter. If you want to learn more about the differences in light for humans and for plants, we recommend the full article on our blog.

The Right Intensity of Light

PAR intensity, or how much usable light reaches the plant's leaves, is measured as photosynthetic photon flux density (PPFD) in the unit of μmol/m²/s i.e. light per area per second. Too little light limits growth and too much will even damage your plants or at least your electricity bill. If you’re growing cannabis, we recommend our in-depth article on cannabis PPFD levels on our blog. Otherwise, our calculator or a quick online search for e.g. “tomato ppfd levels” will certainly help you. Additionally, we've also summarized PPFD requirements in our Pro Guides. Additionally, we've also summarized PPFD requirements in our Pro Guides for cannabis and corals.

The Right Amount of Light

The one measure to express the amount of light is called the daily light integral (DLI). The DLI combines light intensity (PPFD) with the lighting duration (photoperiod) over a 24 hour window and is measured in the unit of mol/m²/d i.e. light per area per day. Ultimately, providing the right DLI level for your plant is what you must do for optimal plant lighting. If you want to learn more about the science of the daily light integral, we recommend the article on our blog. If you grow cannabis, we’ve also written a specific article with DLI requirements across the full growth cycle. To identify the optimal DLI level for your plant, we recommend using our calculator or looking up these values online or in a horticulture book. Additionally, we've also summarized DLI requirements in our Pro Guides. Additionally, we've also summarized DLI requirements in our Pro Guides for cannabis, houseplants, and corals.

How To Take a Measurement

Taking an accurate measurement is easy with the right preparation. Swipe on the main screen to select what you want to measure. Make sure that you are using a diffuser and the correct light source setting. If you don’t know which light setting is correct for your light source, read our guide on which light to choose:

To take a measurement, place your phone at the top of your plants' canopy and aim it at the light source at a 90° angle. Doing so allows Photone to measure the light that falls on your plants' leaves and thus, what actually makes them grow. To ensure you achieve maximum accuracy, read our guide on measurement accuracy:

Make sure to aim the phone at your light source when taking measurements

Underwater Measurements

If you want to measure underwater (e.g. if you have an aquarium), you can do so without any limitations. Just make sure to follow the preparation described in our guide on measuring underwater:

Adjusting Plant Lighting

Now that you know what and how to measure, you need to know how to apply this to provide better lighting to your plants.

Light Positioning

You may find it difficult to spot which window of your house lets in the most amount of light. Similarly, if you’re using a grow light, your light’s output will differ a lot if you measure right underneath it or in a corner of your grow area. Use the PAR Meter to measure different sectors in your grow area and place your plants or your lights accordingly. The light intensity and coverage can be adjusted by changing the height and position of your grow light. If your grow light even comes with an adjustable dimmer, you’re able to dial in the exact PPFD level you want.

Lighting Duration

As you know, aiming for the proper DLI level is what you ultimately want to achieve. If you’re unsure which DLI level is optimal for your plant, you can use the references provided in our Pro guides, our blog, our calculator, or look them up online or in a horticulture book. Use the Daily Light Integral measurement and set your photoperiod accordingly. If you’re unsure what lighting duration to start with, set it according to your plant’s growth stage – usually that is 18 hours for seedlings or the vegetative phase and 12 hours for the flowering or blooming phase. In order to adjust to a target DLI level, try to modify the intensity by dimming or changing the hang height of your light, before modifying the lighting duration.

Grow Light Maintenance

Any grow light’s output will decrease over its lifetime. This means that the same lamp measured today won't necessarily deliver the same PPFD a few months from now, even though it will use just as much electricity. To learn more about when it’s time to replace your grow lights or light bulbs, read the detailed article on our blog. Dirt and dust have a negative impact on your grow light’s output as well. Thus, keep your grow lights clean and measure them every once in a while to see if they need to be replaced. If you want to dig deeper into this, read our article on grow light maintenance.

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