[3 Easy Tips] How to Fix your LED Spectrum for Flowering Plants

A quick picture of me with some of my plants… just one of my growth chambers.

Welcome!  My name is Dan, and I’m excited you’re here.

I study the science of photobiology and let me tell you, not many grow lights out there are giving your plants the colors they need… or want…

I can’t wait to share with you secrets about how plants are affected by color, how most grow lights on the market give out the wrong color, and what you can do about it without replacing your entire grow light system!

Today, we will fix the spectrum in your garden.  This means happier plants and bigger yields await…

Today is a good day to be you!

Use these tips to unlock better growth in your garden with a few simple steps — all under $100 and one is even free!  You’ve taken a solid step forward to fix your LED system’s spectrum.  Your plants will reward you!

By correcting the spectrum, you allow the plants to grow bigger and better.  Traditional LED lights starve your plants of required colors and wavelengths they expect in nature.

Sometimes the colors that common LED grow lights give out are all out of whack and your plants just “deal with it” … but aren’t growing to their full potential.

Just because your plants are staying alive and getting bigger… doesn’t mean they are thriving!  You may have bought these lights online, and of course they work, but have you experienced growth greatness?  Growing alone is hard enough as it is…why should we have to worry about light when all we are doing is trying to save power with LED?

The good news is, most of these fixes require only a small investment, and one is even free!

 After you read this, join in the conversation below and ask questions if you have any.  Feel free to post what grow light you have if you’re looking for specific advice.

I’m excited for you and your garden! Are you ready?  Let’s go.


All LED Owners – Temperature & Airflow Check!


Even though your LEDs might run nice and cool… you do need to keep those temperatures up in your grow tent to get maximum yields.

The High Pressure Sodium bulbs give out a spike of heat that plants actually love, so you’ll actually need to run your grow environment hotter than what you normally would with high pressure sodium.

This is good because letting your room get hotter means you need to use less energy cooling it!

Aim for eighty degrees, but 78-82 degrees is the sweet spot.

Because LED’s run nice and cool, it’s also important to get extra airflow over your plants, they breathe less without exposure to high heat – so be sure you have at least one clip fan blowing over the tops of your plants.


Attn: All Purple LED Light Owners With “Veg” And “Flower” Switches or Color Dials


Does your LED grow light have a “Veg” or “Flower” switch?  If so, stop turning off the  “Flower” or “Bloom” switch for veg …. unless you’re hoping to preserve a small plant in a nursery setting.

Depriving your plants of red light and dumping them with blue light will stunt their growth.  Just check out what happens to lettuce below in a scientific study when blue light % increased…

The reaction of lettuce when exposed to certain percentages of blue and green light.


They found that blue light actually stunted growth by reducing leaf size while also diminishing the rate of photosynthesis.  Crazy right?

What’s more, blue light is the color that causes the greatest stress and light burn.

If possible, run your LED light with both “Veg” and “Flower” turned on.  Back off the light to reduce the intensity, and your plants will thank you in return with vigorous growth!

If you have dimmable dials on your LEDs, during veg try keeping blue lower than what you normally would and observe the results…   Every photobiology study out there recommends Blue light to be lower than 30% for optimal results during vegetative growth for flowering plants.  If you could get that down to 15% it would be even better.

If you have Red/Blue/White switches, try your results with just “Red” and “White” turned on.  “White” actually has a lot of blue light, just enough to give what plants need so that they don’t “stretch”.

Interesting, huh?

Take a peek at your spectrum (more on that below) and use the information above to try to reduce the amount of blue, especially in your vegetative growth cycle because it will change how your plant grows and how big and fast the leaves expand.

Bigger leaves…faster growth…more harvest…

You will be blown away at the results.

During early flowering, when the leaf growth is slowing, turn on all of the channels at max power and let er’ rip.

Trust me…. I know it sounds like one of those statements on the back of a Microwavable Popcorn bag that says “Do not use your Microwave’s ‘Popcorn’ button” … but seriously… don’t use your grow light’s veg and bloom switches as they are intended.  You will end up with smaller yields.

Drop me a note below with a comment and click “Submit” with any questions and I will respond and help you “fix” your grow light’s settings! 


All Purple LED Light Owners


We’re trying to do two things with grow lights that have mostly red and blue in their spectrum…

  1. Blue Light Correction – This is the most important step to fix if your grow light has primarily blue light.  If you own a “ViparSpectra” this is definitely a step to take for you (this light is really meant for aquariums).  Try to find the manufacturer’s web page.  You’re looking for a spectrum graph.   You can also count the number of red and blue LEDs to get an idea. If there is an equal or higher amount of BLUE than RED, you’re going to want to fix that for all stages of growth.  We want blue light to be UNDER 30% and OVER 10% of the total spectrum.
  2. Full Spectrum Correction – Our goal here is to nourish plants with some full spectrum light (green/yellow) to help them thrive with more light information.  In addition, that should help your eyes out!  Adding white light will assist you in caring for your plants so you can see them in natural color.  A win-win!


My recommendation is to add a 50W Warm White LED Flood Light to your garden.  It’s about $35 with CREE LEDs, so you cannot go wrong.  Above all, it will snap most blue-heavy or red/blue spectrums into balance.  These flood lights are great to have around and I use them myself!  They are fantastic to use on their own for young seedlings and can easily be positioned into tight areas of your grow space.

Plus, the more light sources you have in your grow space, the better light penetration and spread you will have.  This means a bigger usable grow area and more growth deeper in your canopy.  What’s more, you can experiment with positioning these lights to the side and getting more angles of light sent towards your plant that will create bushier growth… Talk about an upgrade!

To start, find out how much your grow light pulls from the wall, not the advertised wattage.  For example, the Viparspectra 300W, while advertised at 300W actually pulls 136 Watts from the wall.  Be sure to find the right number.  You’ll have to search for it!

You’ll want to take Total Watts / 2 and shoot for that in your supplemental lighting.  So if Total Watts is 136, half that is about 70W.   We want about 70W of supplementary light.

If you have a ViparSpectra 300W, we’d want 1 or 2 50W Warm White LED Flood Lights for our light supplementation project.

What are you waiting for?  At such a low price to get started with just one, you can’t go wrong.



White And Purple LED Light Owners (The Best Solution)


Buy a low wattage HPS Light!  You will not regret it.  I work with production-level growers and if they are growing with LED, many of them are also supplementing with HPS bulbs.

The reason?  It works.

I know it seems counter-intuitive, but you will save MORE energy by getting GREATER YIELDS with the kind of yellow, red, and infra-red light that the HPS puts out.  Simply providing just a little bit of the colors that are missing in white or purple LED systems will unleash a huge amount of growth in your garden.

The quality and quantity of your harvest will increase for just a small investment…  It will snap your purple and white LEDs and turn them into a monster grow setup.

You will want to supplement your grow ideally with a 1:1 ratio of LED to HPS power.  Half HPS power is great as well.

For $70 and only 150 Watts of power, how can you go wrong?





What about Next-Gen LED Technology?

I never thought you’d ask!  If you’re waiting for the next big thing, you’ve come to the right place.

Now that you’re here and learning, check out how plants use light and watch the video article to learn even more!

Keep growing green my friends, and don’t forget to leave a comment below!


159 thoughts on “[3 Easy Tips] How to Fix your LED Spectrum for Flowering Plants

  1. James Reply


    I’m a commercial Grower based in Oklahoma and I’m using the Electric Sky 300’s as my primary lighting source in many of my rooms. I have a couple that supplement with HPS – Holy Smokes; you weren’t kidding about this upgrade. I am curious about a singular detail though.

    I’m not the original Grower for this operation, the third, in fact. I have noticed a major spectrum difference between all of these systems. There seem to be two, possibly three different light spectrums present here. I see some lights are warmer than others; there may be a handful that are between the two, as well. Every light carries the same model number so I cannot determine if this has been an intentional spectrum shift, or if it’s simply a result of batches of LEDs from your suppliers. Care to shed some.. light!?😝😂

    Thanks for any information you can offer.

    Oh, by the way, the number and layout of red chips seems to be the same across the board. The only change looks to be the white chips; half are cool temp, the other half warm. Every light has the same white color temp, individually, so I could easily re-hang the cool systems in my veg rooms, warm in bloom. Thanks again.


  2. Garymuesch Reply

    I have a ppf 800 1 switch high n low which do I use 2 grow n which 2 flower

    • davidm Reply

      When using a light like that, it is best to just leave both switches on.

  3. tobias Reply

    Hi Dan,
    Great page with lots of good advice.
    I’ve just changed from HPS to LED with red white and blue dimmers. It also has UV and IR.
    I’ve never used led before and really need some advise if you don’t mind.
    I grow from seed for 4-5 weeks then move them to the main grow area. What combination of red/white/blue do I use from this point until harvest?

  4. John Reply

    Just wondering if a far red initiator puck would be of any good when using the ES300 v2 or v3. Some use it to assist with putting the plants to sleep is my understanding and it supposedly assists in initiating the flower cycle. Dan mentions this in his newest video with Mr. Grow it. I understand the ES300’s are much different than other lights in terms of spectrum and effect and before I purchased them I had also looked at these Far Red pucks or diodes. They would be easy to DIY and there are now a couple companies selling them.

  5. Dan Skroko Reply

    Orig Glue Auto. I have a MZVUL…100w 186 LED 3 Modes, Full Spectrum Grow Bulb $25 Amazon. I Put my Seedling under Blue light From CFL and it Immedietly Drooped …..Put CFL back on and MAGIC…Back to Perkyness. What can i do to Fix what I have? My Light will Not let me Use 2 Spectrums of Light….1 or the Other? Blue Veg or Red Bloom Buttons? What do I do? I am going with CFL until the Flowering Starts and Put in the led and Go to Boom?? Yes /No Thank you Dan

  6. James grant Reply

    I liked what I read and I am glad to have your opinion. I currently have a spider farmer 1000. Should I turn it down to vegetate at run it and 100% for flower? Is it the right light spectrum? and if not how do I change it.

    • davidm Reply

      Hey James, the spider farmer can be good budget grow light. However we’ve found that our light fills in a lot of the spectrum their light is missing for improved quality and yields!

  7. Kenny Reply

    Hi, I’m fairly new to this, after just using hps bulbs, I won’t to try leds, what would be the best all rou nd lighy to purchase, for a small I door garden, approximately 3 plants, do all leds have veg to bloom switches?, thanks and appreciate any help given, yours, ken

  8. Chris Reply

    Thank you for taking questions. My light is an Apelila 3000w / 576 LEDs / 320w power draw/ 372 full spectrum purple (25% blue) / 8 lime / 182 purple (2.5% blue) / 8 UVA. -Blue 12% – Green/yellow 20% -Red 57% -FRed 8% on Amazon for $136. I have a 3’x3’x6′ tent. I would like to add some cheap additional lighting, would adding 1 – 2 50 – 75w soft white LEDs throw my balance off to much.

  9. Chris Reply

    I am growing vegetables. My grow light has a veg switch (blue lights), bloom switch (red lights), or both switches on creating a purple light. What light color(s) should I use?

  10. Bavis Reply

    600w “blurple” LED, 5 weeks into flower. I’ve been running both switches to this point. I’m considering running just the deep red Bloom switch for the first hour of light and the last two hours each day. Then full spectrum for the other 9 hours. This is with the idea of transitioning to just running the bloom switch for the last week prior to harvest. Does this sound like a good idea?

  11. Fernando del Real Reply

    Hi! I am using norlma warm light leds, I was wondering, how do I know how much light do I need?

    Greetings from Mexico

  12. Mr Greenfinger Reply

    I have a viparspectra va1000 dimmable, my
    plants are 10 days old, still babies, but I’m having a big stretching problem, I followed the guide and I have them to 50% bloom and 75% veg, they’re growing well but they’re stretching a lot. Should I move the light closer? atm they’re about 13-16 inches away from the canopy and they’re still in the humidity box. Should I open the container?

  13. Moe Reply

    I am having some trouble. I have a 600w viparspectra WITHOUT bloom switch, which from what you wrote, is pretty unnecessary anyway. There is one plant and it appears to be getting light burn when I lower it the light. To have it on 100% intensity for bloom, I have actually had to raise the light and am already on a 12/12 schedule hoping to flower. Should I just keep gradually lowering while also turning down intensity? Should I be supplementing with a red light? Help!!! I am a beginner.

  14. dean Reply

    First time grower.
    1000 watt LED
    Pushing plants 12 /12 hrs for hair phase. Should I keep my VEG/ BLLOM lights on or just use my BLOOM lights?
    photo plants / Sog style

  15. Lilman Reply

    Hi, I would like to ask if its ok to use cfls for supplemental light when using led? If so, any tips

    • greensunshine Post authorReply

      Hi Lilman yes if you have CFLs around the house the more the merrier, but CFL need to be close to the plant, so perhaps place them on the edges. Would not go out of my way to purchase these for grow lightning, however

  16. Keith Reply

    I have a Mars Hydro TS 3000w LED equivalent to 800w-1000w HPS, two 1500w Carambola red bloom LED’s I’m guessing run a couple hundred watts a piece and a 40w white led shop lights running vertical for side lighting. My question is with the Mars Hydro led. It has a dial to turn the intensity up and down. With it all the way up it is real bright and puts off a lot of white light and heat. Should I dial it down and lower the lights with this? Some times I afraid I’m not giving enough light when I actually could be giving to much. I’m not sure because my second grow is lagging and I think it’s because summer is here and the tent is warmer.

  17. Aubrey Swinson Reply

    Hello! I’m using 2 450 watt viparspectra and one 300 in the middle. Currently I have two plants in a 2x4x5 tent. Right now they are in their 6th week of flower. The issue I’m having is the temp goes to around 85F. I added a air duct for cooling from my ac vent but doesn’t seem to help. Should I keep the 450s on bloom only and use the 300 on max to keep the temp down? Thanks!

    • greensunshine Post authorReply

      Hi Aubry 85 degrees is barely OK for LED. You might want to try getting a better airflow situation for your tent, and reduce the temperature of the room itself for the cooling. As long as your plants are happy, should be good to go!

  18. Brian Reply

    Hey! You’re super cute. Running in to an issue with the heat in my tent with both veg and bloom switches on. I have a 4×2 tent and am currently running an advertised 2000w and 1200w led. Thoughts?

    • greensunshine Post authorReply

      Hi Brian! Make sure you have adequate airflow. Go extra and get a fast fan and that will clear out your grow tent!

  19. steven f Reply

    hi mr greensunshine I’ve got a 2-600w viparspectra with veg and bloom switches, would you advise to keep switch off veg switch in veg as, ive added 200watt off warmwhite floodlights .and when in flower turn on veg switch ,i was running metal halide 400w but the temp was to hot ,

  20. visionrouge.net Reply

    Thanks for these tips.
    I’m working on a blooming flower video only.
    which color do you recommend for speeding up this part?
    The flower come out of a fridge every morning and I’m trying to get them open in 2/3 day time if possible.
    Do I still need a bit of Blue, or I should focus on Yellow and red only?

  21. Marc Pominville Reply

    Hello Mr greensunshine,

    I just bough a Growstar S600 ( months ) and many little flood light to help the blurple light to add more coverage and penetration also add more red with a 2700/3000k temps flood light .

    I am very happy to discover that I was not wrong with the blue spectrum.

    I already got a Par meter and I am building my spectrometer to pin-point the right amount of blue to my setup…

    My setup is for my seedling of citrus plant , it’s hard to found some specific data in regard of the culture of citrus like Par level quantity , do you have any suggestion where I can find that kind of info ….not the number which will great, but place like university or site that hold that kind of info.

    Thanks and it was a pleasure to read your page.

    Marc P.

  22. Chris hill Reply

    Hi there so I have 2 1200 wat kingled and a 1000wat led with a dial to turn the lights up and down now I’m just starting budding should I run both veg and bloom light and are the lights I have any good my plants are doing amazing in veg but ow it budding time and I want to know for sure lol thanks so much

    • greensunshine Post authorReply

      Hi Chris, yes use both of the veg/bloom switches!

    • greensunshine Post authorReply

      Hey Jerry, Those lights would certainly “get the job” done for seedlings, the lights themselves don’t look too powerful at 18W. I would use at least four if you wanted to cover a 4×4 area, definitely experiment. Not sure of their efficiency but if you have them try it out.

  23. MadeToLoveMagic Reply

    Hi, firstly thanks for a great article. i’m using a 1200 watt Viparspectra on my first grow and i was wondering what you’d suggest to supplement? Would a HPS light be better than a warm light LED floodlight for blue light correction? I know u said 1-1 ratio for HpS and LED but obs i’d then be running 3000w in a 4×8 space – would that be too much?! Would a 250watt HPS bulb be okay do u think? thanks 🙂

  24. MadeToLoveMagic Reply

    Hi, firstly thanks for a great article. i’m using a 1200 watt Viparspectra on my first grow and i was wondering what you’d suggest to supplement? Would a HPS light be better than a warm light LED floodlight for blue light correction? I know u said 1-1 ratio for HpS and LED but obs i’d then be running 3000w in a 4×8 space which seems a lot! Would a 250watt HPS bulb be okay do u think? thanks 🙂

  25. Rabbit Reply

    Do you know where to get lights with this optimum spectrum you speak of in one setup?

  26. Charles McKenzie Reply

    I’m wondering if a floodlight with 2700K warm white light, 1200 lumens, CRI > 85Ra would work as a grow light in the vegetative state? Reason I’m asking is because it also has color changing that syncs up with your cell phone to change the light color. Thanks.

  27. Jason Charles Reply

    Hello, I recently started growing hemp under a bestva 3000w led. My plants are autoflower and I want them to grow as big and as fast as possible. Should I be running my light on veg only? Or bloom and veg both? My light is about 24in above the plants

    • greensunshine Post authorReply

      Hi Jason, I would turn both of the switches on and let it rip! Back off the light 1 foot and then turn on both of the switches, observe plant health and adjust height as necessary, good luck! -Dan

  28. Levon MacRae Reply

    Hi there. Great article and thanks for the info.
    I just have one question; I’m running a viparspectra 300w but I wasn’t clear if I should use the supplemental warm white led’s in veg stage or flower stage or both?
    If you could let me know that would be great.
    Many thanks 🙏

    • davidm Reply

      Hey Levon,

      Yes some white LED’s will help balance out the spectrum of that Viparspectra. I would use it in both veg and flower for best results.


  29. Eva Reply

    Hi there, wow so many great tips! Can we please ask a question? Our indoor plant growing device has three modes, full spectrum, Veg. and Flowering. We’re growing hot peppers. We understood that we start with full spectrum first, is that correct? Then what? At what stage switch to flowering? or Veg? or just stick to full spectrum?

    • greensunshine Post authorReply

      I’d stick to the full spectrum! =). You can add in the others when the plants are big.

  30. Cg Reply

    Hi, I’m growing legal cannabis and during the vegetative and early flowering phase (the 2 week “stretch” for cannabis plants) the goal is for plants with extremely short internodal distance and low, bushy growth. Currently, I’m running them under just the veg switch of my LED and I plan to continue until they begin to produce flowers, then I’ll switch to my 3000k full spectrum 600w actual draw quantum board LED. Do you think this is a good plan to produce plants with very tight internodal spacing by the time they begin to flower?

    • davidm Reply

      Yes the lack of red light will reduce the amount of stretch in the beginning phase of flower.

  31. Jeff Reply

    I ordered no name Chinese LED grow light listed as 800-1200w. 4 COB. Arrived 1200w. No idea of light spectrum. Switch turns on/off 2 COB’s.
    Do I assume half power is 600w?
    Plants seem to like two lights more than four. Currently have 5 autos growing mostly indoors.
    I know asking for help with this info is a lot. I’m dealing with a language barrier.

    • davidm Reply

      Hey Jeff,

      Is there a driver exposed that would show the actual wattage of the light? Or you could also use a meter to see how much power it is drawing while on. Having a better idea of total power will help you adjust as needed.

      Thanks, David

  32. John Reply

    I have a 3×4 room with a viparspectra par 600, with the intention of having a 30 in diameter plant to keep it within the specs for flowering. I’ve been running all the lights, red white and blue, the plant is growing very well but it seems to be a little too bushy. After reading your article I too turned off the blue light. Is this the right move for the light I have, or should I turn the blue back on and add more white like you mentioned in the article? I’ve always grown outdoors this is my first time indoors so any help would be helpful. Thank you

    • greensunshine Post authorReply

      Hi John, Turning the blue off will make the plant grow bigger, you can probably drop the light a little closer to the plant with the red and blue on and it will start to stretch out the way you like and get larger. Once you get close to flower, turn on all the colors and you’ll get a great finish.

  33. Deivid Reply

    Thank you for you response.

    Can you please explain me is that high peak in blue spectrum in Mars Hydro TSL2000W means that plants mostly can absorb blue light? Ratio for blue colour as you discribed to find in your post is only 2.2% in comparison with other colours. Most are green that gives that high peak in blue spectrum that’s how I understand it but is that mean that plants mostly get blue light photons from this light?
    Blue: 2.2% red: 19.5% green: 78.3%

    • davidm Reply

      This light uses a lot of white diodes for effieciency which tends to run a little blue. Adding some additional red and deep red will increase flower production.


  34. John Ballard Reply

    I have a 2000 Watt King LED when would I use the veg and bloom mode at the same time and also wanted to find out about misting the leaves with water is it okay or not

    • davidm Reply

      You are going to want to use both switches when in flower to get every watt you can from that light. As for misting my plants, I don’t find much benefit unless applying a solution for purpose.


  35. Ansel Wade Reply

    This is exactly the reason I purchased from The Green Sunshine Company – Here is the Owner helping non Green Sunshine folks work their their light issues and sharing knowledge freely …. Love the ES180, best grow I’ve ever had, thanks Dan!

  36. Andrew Reply

    Awsome read brother how do I sign up for emails when you come.out with new info. Also quick question so if i wana keep mother plants and dont want them growing crazy just veg would be appropriate yea?

  37. Justin Reply

    I really liked the read. But I just wanna ask, when flowering is it better to run both veg and bloom settings all the way up? I have mine set with veg down to a minimum before it turns of veg mode and bloom all the way up when i flower.

  38. Alan Reply

    Very comprehensive and informative… Thank You!!
    I had 2 separate single grows last year using a 600w Viperspectera in a 2×2 grow closet…. both plants vegged great, but the flowering was a bust.
    After reading your article, I installed 2 clip on work lights with 100w Sylvania LED soft white floods. I’m into day 18 of 12/12 light change, she vegged great, got alot of hairs coming on, hope I have success.

  39. andre brown Reply

    Hi Greensunshine, thanks for your awesome post.

    I’ve got a 2-600w viparspectra with veg and bloom switches, would you advise to keep both the blue”veg” and red”bloom” light spectrums during the veg and flowering stage ? my plants seem to be growing very nice so far and I have only been doing veg light for veg since early growth there about 20 inches now . this is my first time using led I have venom go and the temp is about 78. thanks so much also I’m going to get the light as well..

  40. Mike Reply

    Hi was hoping for quick advice. I have 2 Aglex 1200w cob led lights both with veg and bloom switches. I’m running in a 4×4 tent is that too much light with both running full power? Draws about 200 actual watts each from thd wall. First timd grower 4 weeks into autoflowers.

    • greensunshine Post authorReply

      Definitely not too much light 🙂 . Could use more, actually.

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