This might seem daunting.... but let us take it a step back and add a definition to the terms you see when purchasing grow lights and what you really need to look for. I promise it is not that bad, or boring once you understand!
Starting from the beginning:
What is photosynthesis?
Photosynthesis is the process in which a plant converts light to energy. This is a necessity for plants to feed, grow and thrive.
Light behaves as both a particle and a wavelength
This impacts how we see and how plants absorb
What is a Watt?
Unit of power
(1 J/s)
Rate of energy transfer
A 42 W bulb ran for 30 days and 24 hours a day with a cost of 0.12 cents per KWh, you would be looking at $3.63 to run this grow light (one grow light). The package I have came with 6 lights, 6 times $3.89 = come on folks.. 21.78.
Although this is meaningless for your plants, you should know the wattage will affect power consumption. The grow lights I am referencing today have 42 W.
Click Here for the 4Ft T8 lights I chose:
Click Here for the Single 3-pack bulbs I chose:
Moving on!
What are Lumens?
Lumens are the total quantity of visible light exerted from a source, based on human eye sensitivity to certain wavelengths.
Not always useful when choosing your grow lights
(if you come across this measurement you can assume 2000-7000 lumens / ft^2 will suffice for growing stages; 7000 being highest)
2000 low growth
4000 vegetative growth
10,000 highest light (think noon)
What are Lux and Foot Candles?
Lumens/ft^2
Not useful when choosing your grow lights
What does PAR mean?
Photosynthetically Active Radiation
Describes large range of lighting wavelengths plants use for photosynthesis
The PAR spectrum is between 400/700 nanometers
What does PPF mean?
Photosynthetic Photon Flux
Measures total amount of PAR produced by light in a given second (μmol/sec)
Essentially tells you how efficient a light is as producing PAR
What does PPFD mean?
Photosynthetic Photon Flux Density
(μmol^2/sec)
Measures PAR that actually lands on the plant
Measures photons that reach a given surface
This IS IMPORTANT when choosing your lights as a low or high PPFD will indicate whether the light is good for low light plants or plants that enjoy full sunlight.
Direct sun loving plants = high PPFD
Shade loving plants = low PPFD
Hight Flowering/Fruiting = High PPFD
Note: You can change distances of some lights to meet your PPFD needs
Real life example of why PPFD is important:
For the grow lights I purchased to test out this year, this is what they recommend, the suppliers should always show what their PPFD is so you know how to place their plants. They do the calculations for you!
So you see here, 11 inches for germination and vegetative in process stage. While the fruiting and flowering stage shows you should have the light placed closer at 7-11 inches. While these are great calculations, always check your plants daily when germinating and growing because they can get leggy reaching for the light, you can always lower them.
What is the main purpose of your grow lights?
Grow lights help promote photosynthesis
Provide supplemental light
provide full light in a grow room to mimic the sun
Why are most grow lights blue and red (or pinkish)?
Easy, blue and red are on the PAR scale that plants photosynthesize well in. Plants absorb red and blue light with ease, while us humans like yellow light.
Remember PAR? This is the spectrum also known as the McCree Curve. This shows where plants and humans fall when it comes to seeing and absorbing light.
What stages should I be aware of when determining which grow lights to use?
Seedling growth
Intermediate stage of growing
Fruiting/flowering stage
What is a 3,4,5, 6000K light bulb?
5000K is ideal as "direct sunlight" or full-sun
4000K for example is good for house-plants or plants in their intermediate stage, they aren't seedlings and they aren't requiring a high amount of light to fruit or flower.
I personally use these over winter in the grow room for "light sustenance" for my plants. This is for the 3-pack of lightbulbs I am discussing in this post.
So,
Down to the nitty gritty. Which lights did I choose for 2025? Well, here they are!
I chose these specifically for:
Length of my metal wire shelving
Can be used at different heights.. to account for high or low PPFD
Has a low wattage so less money spent
Has pink lighting which mixes your blue and red light which plants love
Link to 6 pack of 4ft T8 lights:
Bulb Type: T8 Plant grow light
Info:
Full spectrum
42 W
High PPFD (now you know what this means!)
V Reflector (keeps light within your plants range)
Zip tie type hanging
on/off switch
Plug into wall individually or hook together with connector wires (included)
Link to 3-pack of single bulbs
Bulb Type: A19 bulb
Info:
11 W (hey this is pretty good!!! 1/4 cost of those 4ft lights up there)
4000K LED Grow Lights (don't confuse this with lumens!)
Looking for a review on these specific grow lights?
Stay tuned as I constantly add videos and updates on Instagram, TikTok, and Facebook.
You can always reach out with questions!
Thank you for joining me on my grow room adventure!
~DIY With Chelsea
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