[Ep-30] LED Grow Lights: How Optical Data Helps Your Plants Receive Better Lighting
Updated: Aug 30
This article introduces how to choose and use plant LED lights.
Ordinary lighting bulbs have spectra unsuitable for plant growth, so you need LED lights specifically designed for plants. When choosing plant lights consider the plant's compensation and saturation points, as well as spectrum, power, color temperature, CRI, and PPFD data.
Table of contents
Plants need sunlight,
However, if you don't have outdoor space or your indoor area doesn't get enough sunlight (at least about 3 hours of direct sunlight), or due to outdoor weather factors like extreme heat or cold, strong wind, heavy rain, or pest problems, consider moving your plants indoors.
At this point, plant grow lights will be the savior!
Why must the LED light be 'for plants'?
Because most indoor lighting is focused on increasing illuminance, and high-illuminance lights don't emit much of the wavelengths plants use for photosynthesis!
Briefly: the wavelengths effective for plant growth are mainly in the blue and red regions (which is why some growers and experienced plant hobbyists use blue+red 'purple' lights).
In general, blue light promotes root growth, red light promotes leaf growth.
Home lighting typically boosts illuminance using blue, yellow, and green bands; the blue-to-red ratio is uneven and red is very low, so lights not specified as plant-spectrum are usually of little help for plant growth!
[Top image is a common household LED spectrum, bottom image is a plant LED spectrum]
Criteria for choosing plant grow lights
Above we mentioned blue and red are the main spectral bands used by plants,
but if a plant light only has these two bands it becomes a 'purple' light.
Shining it on plants affects how leaf color is perceived and can even interfere with diagnosing pests and diseases,
What's more to note isthe blue band can be harmful to the human eye.
So if you want to comfortably enjoy your plants every day and give your eyes a 'spa',
we recommend choosing'full spectrum'plant lights, that is, lights that mimic the sun's visible spectrum across the seven bands.
Although plants may not use every spectral band fully (each band still offers some benefit; it's not only blue and red), the emitted light looks natural and comfortable, closer to daylight, and blends better into normal home interiors (it's not a propagation facility — we've even seen news of purple grow lights causing misunderstandings with neighbors...).
Besides looking at the product's spectral data, we've compiled key optical terms and data meanings to consider when choosing plant lights, using the <Barrel Octagon 50W> full-spectrum LED plant light as an example:
《50W》
Power rating; it represents the bulb's power consumption over time (normally higher values produce more heat), not brightness.
《Color temperature (K) 3000-5000》
Typically between 3000–6000K: higher values are bluer/whiter (cooler), closer to midday sunlight; lower values are yellower (warmer), closer to dusk sunlight. The Octagon can be adjusted via its app from 3000–5000K.
《Color rendering index (Ra) 96》
This indicates how close the light is to sunlight color; the maximum is 100.
《(PPFD) At a distance of 40cm >610–620 (µMol/m2s)》
Photosynthetic photon flux density — if humans perceive brightness by illuminance (lm), plants perceive light by PPFD. Here it says up to 620 photons land on the leaf surface per 2 seconds at that distance, but distance affects the value: the farther away, the lower the PPFD.
《Illuminance (lux) 26500–28000》
The luminous flux per unit area on objects within the illuminated area (lm). In plain terms, it's the perceived brightness at a given distance — the closer and brighter, the higher the value. This means it can provide around 28,000 lux on 1 square meter.
Recommended light distance for plant lamps is usually between 30–70cm; adjust the distance and number of lights according to the species' light requirements. This relates to the plant's minimum and maximum light values,
i.e., the plant's compensation point and saturation point.
If your budget allows, we recommend choosing plant light brands that provide optical data; Japanese and Taiwanese brands tend to be more reliable. Chinese brands aren't unusable (whether good or bad, many act as OEMs for Japanese brands).
However, the data provided by their own brands can vary, so you need experimental spirit and time to verify with your own plants,
and Japanese brands carry the Japanese electrical safety certification PSE, which gives extra peace of mind.
Compensation point and saturation point
They are the minimum and maximum light values plants require.
Once you know what kind of light (quality) plants need, let's look at the quantitative side (amount).
Put simply, it's the minimum and maximum number of photons plants need for photosynthesis.
Most plants can photosynthesize effectively between their saturation (maximum) and compensation (minimum) points,
When light exceeds the saturation point there is a high chance of photodamage or sunburn; below the compensation point plants only survive, with growth stopping, etiolation, or even wilting.
When relying on sunlight, you must adjust plant placement according to other environmental factors like temperature, cloud cover, and season — which beginners often find hard to judge, and it's difficult to tell what intensity 'full sun' or 'partial sun' actually means.
Using plant lights you can adjust plant position and distance according to photon output data, and maintain stable quality (we'll set aside the topic of UV effects on plants here).
Common foliage plants and Araceae generally prefer partial sun light levels, about 200–375 PPFD. At these levels, it's not recommended to expose them for more than 6 hours.
So, after understanding what these numbers mean, managing 'light' becomes much easier! 'Full sun' is roughly over 2000 PPFD within 6 hours, while 'partial sun' is about 300–400 PPFD over 4–6 hours…
Explaining things with data is often the most universal and easiest to communicate. That's why we keep studying these details.
PPFD values required by different plants can usually be found online, provided you know the correct plant name or family. If you'd like to know which light-metering phone app we use, leave a comment saying 'I want it!'
Also note that the distance from the window has a significant effect on light levels:
Moving 10cm away from the window cuts light by about 70%!
Another article introduces plant lights whose timers, brightness, and color temperature can be set via phone:Click here
If you are still unsure whether light is the main constraint, start with the Plant Environment Setup Diagnosis before deciding whether to add a grow light.
Everyone's growing environment is different; learn to observe.
Plants usually need time to acclimate after being brought home; the more the environment matches their natural habits, the faster they adapt. Sometimes environmental change triggers accelerated metabolism and some leaf drop — that's normal. Observe your plants' changes closely.
Taking photos is also a good method to compare changes over time.
You're also welcome to share photos of your plants in our Facebook Group:https://www.facebook.com/groups/5258158664267819/?ref=share
Our planting courses
have earned the trust of many domestic and international companies and brands (Our profile)
They can of course help you quickly grasp correct planting knowledge.
If helpful for your life or work, click the link below to learn more
Thanks for reading to the end!
We update articles monthly; if you find them useful, please register your email at the bottom of the page,
to subscribe to our updates for free.
If you have plant questions, feel free to book an appointment with us:
or
Click the image to join our 'Plant Study Space'
On our website (you must become a member first, then follow the link to apply to join):https://www.greencapsulehk.com/groups
Facebook Group:https://www.facebook.com/groups/5258158664267819/?ref=share
<<Click here for our YouTube Channel>>
----More plant and potted design videos are continuously being updated----
Learn about the Platycerium mounting workshop:Platycerium Mounting workshop :https://www.greencapsulehk.com/service-page/platycerium-mounting-workshop?referral=service_list_widget
Choose a moss bonsai workshop you're interested in and sign up to join us at the studio!For more about mosses and bonsai, you would like to come and join our workshop：https://www.greencapsulehk.com/workshopFor latest works, workshops, and information please click:Stay close with us:https://www.instagram.com/greencapsulehk/
You can also find moss bonsai materials and DIY kits hereAlso can grab some bonsai supplies and DIY kit from here：https://www.greencapsulehk.com/shop
![[Ep-33] Barrel Plant Light: ROKI-Octagon-50W](https://static.wixstatic.com/media/1bdabd_98a6b3898191425f97d1ed2cf22877b8~mv2.jpg/v1/fill/w_980,h_980,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/1bdabd_98a6b3898191425f97d1ed2cf22877b8~mv2.jpg)
![[Ep-31] 復古風植物 LED 燈 - TSKUYOMI 10W AKADAMACHAN MODEL 植物育成LED](https://static.wixstatic.com/media/1bdabd_5b992266ad524aa6b9b911de672614ac~mv2.jpg/v1/fill/w_800,h_800,al_c,q_85,enc_avif,quality_auto/1bdabd_5b992266ad524aa6b9b911de672614ac~mv2.jpg)
![[Ep-04] 全日照-半日照-半陰(散射光)？](https://static.wixstatic.com/media/1bdabd_f641c0197fa248008b260f541df1b7a9~mv2.jpg/v1/fill/w_980,h_842,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/1bdabd_f641c0197fa248008b260f541df1b7a9~mv2.jpg)
Comments