Welcome to UK420

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customize your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more!

This message will be removed once you have signed in.

Sign in to follow this  
Followers 0

Why I use and prefer LED grow lights!

59 posts in this topic

I know when I first got into LED growing I was the classic HPS devote, borderline religious fanatical zelot, like i'd throw a Jihad if anyone said a word against the sacred HPS units and their lovely bright Son-T-Agro bulbs for all they had done for me and everyone I knew of the faith, but, one day ......

Well one look at the few pics i have loaded so far to UK420 and it is clear that I only grow with LED nowadays

Ice from Nirvana at 6 weeks under 5 band LED Red(660nm) / Red(630nm) / Blue(455nm) / Orange(610nm) / Yellow(585nm) 3w diodes running at 70% (I am assured) this is to prolong the life of the diodes to 10 years each, I have CREE LED units that run higher but lets not confuse it right here :wallbash:


Exact same plant just before leaching under natural light with a background


Once you get into using the right LED and see the change in your plants vigour and health you don't need any science hebegeebee to convince you it works or why.

Before you have used them especially if you are well experienced in the well known and well written ways with solid paths to follow it is like hearing a heretic talk about using magic instead of your religion to grow your sacred medicine.

Gonna see here if I can throw in some of the simple science I deciphered from sales patter and from harrassing companies that produce the units, for those wanting to take the leap but finding the leap a big step to take this might help you find the right light for you and your setup.

Please do not send me endless links to products asking me to vet them, for 1 they be a chore for an admin to remove as they are against site policy and for 2 after reading this you should know yourself if the unit you are looking at for £17.99 is shit or not :yinyang:

So then here goes

What type of lights do plants need to grow?

Really this is the most important issue to bear in mind when comparing different types of grow lights.

Traditionally light bulbs have been measured in terms of Lumens.

Lumens is a measurement of VISIBLE light to the human eye!

The higher the Lumens rating on a light bulb the brighter the light will appear to the human eye!

When we're thinking about the lighting needed to grow plants we need to gain an understanding of what specific types of light plants respond to.

Traditionally the solution has just been to use the most powerful HPS / HID lights which although very effective only have a small percentage (approx 15-30%) of their actual output in the correct spectrum for plant growth.

One of the many key advantages to LED lighting is that the wavelength of the LED can be specifically manufactured to coincide with the wavelengths that plants require to grow.

This means more efficient at converting electricity to light that stimulates growth.

LED's used for growing can also be refined only to produce the spectrum of light which the plant will use to grow.

Simply put, watt for watt LED can be 15 times more efficient than HPS / HID lighting at producing growing light for plants.

This means less heat, and less electricity costs.

Below is a chart of the plant growth plotted against light wavelengths.

From this chart it is possible to see which wavelengths of light will produce growth in plants.

It allows a specification of LED light to be produced which outputs only the light at the wavelengths which are useful for plant growth for the maximum growth potential.

How Sunlight effects plant growth


The wavelengths of light are on the horizontal scale

The plant growth response is charted in the vertical axis (higher numbers on vertical axis = better growth as measured by chlorophyll production)

Below is a break down of the different wavelengths of light (plotted along the horizontal axis of the above image) and the effect each one has on plant growth.

200 - 280 nm

UVC ultraviolet range which is extremely harmful to plants because it is highly toxic.

280 - 315 nm

Includes harmful UVB ultraviolet light which causes plants colors to fade.

315 - 380 nm

Range of UVA ultraviolet light which is neither harmful nor beneficial to plant growth.

380 - 400 nm

Start of visible light spectrum. Process of chlorophyll absorption begins. UV protected plastics ideally block out any light below this range.

400 - 520 nm

This range includes violet, blue, and green bands. Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis. (promotes vegetative growth)

520 - 610 nm

This range includes the green, yellow, and orange bands and has less absorption by pigments.

610 - 720 nm

This is the red band. Large amount of absorption by chlorophyll occurs, and most significant influence on photosynthesis. (promotes flowering and budding)

720 - 1000 nm

There is little absorption by chlorophyll here. Flowering and germination is influenced. At the high end of the band is infrared, which is heat.

1000+ nm

Totally infrared range. All energy absorbed at this point is converted to heat.

Breakdown of it all and what it means in regular terminology

The above information can be simplified into a measurement called PAR (photosynthetically active radiation )

This measurement is similar to Lumens, however whereas lumens measure visible light output (to the human eye) PAR measures light output of wavelengths which are applicable to plant growth.

Very simply put, the higher the PAR reading the better the light for plant growth, regardless of wattage and regardless of Lumen output.

The Peak growing wavelengths for plant growth occur at 425nm and 460nm and again at 640nm and 670nm.

To get maximum plant growth it is ideal to target any lighting specifically around these frequencies.

Any lighting out side of plant growth frequencies can actually be damaging to the plants as described in the data above.

The lights I go for have a mix of spectrums covered (Red(660nm) / Red(630nm) / Blue(455nm) / Orange(610nm) / Yellow(585nm)), as us canna growers know it is more than just red and blue, a little is needed from elsewhere on the scale affecting germination and flowering, this is where most inferior units let us down when aiming to produce medicinal grade donkey dicks in a small space without that space having to be the inside of a working freezer to handle the heat of the light confined.

Hope that helps :wassnnme:

8 people like this

Share this post

Link to post

Interesting as it is....I'm still 100% sure that LED lighting is still a long long way behind HPS for your average percy grower.

15 times more efficient than a 600w sodium? can't wait to see that..... just how many LED's would you need to produce around 20oz(give or take a few OZ) in a area roughly the size of a 1.2 metre tent? is it even possible never mind being more efficient because that is the going rate for a 600w percy grow?

Share this post

Link to post

In a tent that size i would have 6 to 8 of the units i use.

I currently run 70cm x 70cm x 100cm (scrog is 60x60)with 3 units in and produce around 6-8 oz every 14 weeks including drying which is done in the same box, in mid summer i get around 6 due to external heat issues affecting internal heat issues, autumn winter and spring is the heavier yielding times for me

Edited by GGTBod

Share this post

Link to post

Is that me on the blacklist for life? Permanently self banned through statement from the secret handshake treehouse.

I am not trying to convert anyone from their religion, I am just sharing my experiences as I know from the questions i have already had that a lot of people want to make the change

2 people like this

Share this post

Link to post

What watts are the leds you use mate?

Share this post

Link to post

Each diode is 3w and the controller runs them at 70% maximum possible output, the only diodes that run higher than this reliably are the CREE diodes, the controller can run these at 90%+ of their maximum possible output without them blowing according to claims by the CREE LED diode manufacturers, I have a single 135w unit constructed of 3w CREE diodes running at 90%+ but I have only been using it a short time so i can not speak from experience yet on these specific units which is why i never covered them fully, the units made from these are way more expensive too and for some reason are only covering 3 spectrums so far.

1 person likes this

Share this post

Link to post

Not starting a shitstorm here, and I admire your enthusiasm for leds, but a couple of points:

Your opening thoughts about "HID zealotry" are misguided, in my opinion. Most growers here want the best for their plants, in terms of both health and yield, and I'm willing to bet good money that if an LED light came onto the market that was reliably producing 2gpw or above as standard, we would be all over it. The zealotry usually comes from the LED users themselves, particularly the ones that have paid well over the odds for panels that produce less (or at best, equal) bud per watt, compared to HIDs.

We've all had the "simple science I deciphered from sales patter" put to us many times before, and while it may seem to make sense if you take it at face value, the results just don't seem to add up. Why, for example aren't these panels producing crazy amounts of bud, if the "15 times more efficient" argument is in any way valid? Alternately, why do HIDs produce bud so well, when the majority of their light doesn't even correspond with the chlorophyll spikes that are supposedly all that the plant needs to thrive?

Thie plant has evolved for millennia with a full spectrum to work with, and I'd hazard a guess that it makes use of most of it, one way or another. There's more than just photosynthesis going on, for example the far red band, which your post discounted as being of little use, has been shown to influence stretching, since the plant uses these wavelengths to assess if it is in crowded conditions. This seems to hold true of other parts of the spectrum too, and some of the most successful LED grows I have seen have used far red, IR, UV, green and other combinations of lights that wouldn't make sense to use if the chlorophyll spike thing was the be-all and end-all that these LED sellers make them out to be.

There's no doubt that LED panels are improving, but the claims that they are currently "15 times more efficient" etc. are just not true, and won't be true until they translate to yields.

15 people like this

Share this post

Link to post

I like the idea of it and in time, when prices come down and more market experience is gained I will probably have a crack @ LED, There's no doubting their production capabilities I've seen they can grow plants on the same par as HPS.

Four problems for me tho while I'm here:

1) I grow in the loft, which is super cold in the winter and without the heat from my HPS I would have to increase my heating = more leccy (like I need that) lol

2) I have limited headroom and some of the distances I've seen mentioned from unit to canopy are too large for me.

3) They are pricy, but then I also understand theres no replacing bulbs/ballasts as often etc.

4) Not 100% on this but I've heard some say they are noisy?

This LED malarky is still like a red flag to a bull and you will get mostly doubters so I wish you good luck with this thread man, really lol

CK :v:

2 people like this

Share this post

Link to post

i have also started down the led path to a lesser extent.

I have 2 15w panels that are currently keeping some seedlings alive(although about 50% of them have toppled from stem wilt this morning)

I also spent a considerable sum on half a dozen Cree based panels. However these have been more headache just getting them delivered to the right address thus far.

So im wondering in your extended use of leds, have you used them for seedlings with much success?

Im thinking that maybe its just too unusual for them at such an early stage?

Also im interested in the 135w cree panel you have, do you have a link or some google ref?

Watering is going to be totally diff without the evap rates of HID's

but i cant wait to see a decent RDWCLED Harvest... The HPS/MH & A/C are just too expensive for me now.

Share this post

Link to post

The CREE unit is called 135w Cree LED UFO, i can not link as it is against site rules, i'll try and answer any questions better after some sleep, i had a couple edibles at 1am and typing and thinking together is getting tricky.

I use led for seedlings but i use the same light that i use for flowering and veg, I know the boards you speak of and I would not advise them for canna ( they are great fro growing cacti seedlings) for seedlings my light is just at 30cm distance instead of 5cm as in flowering, the little seedling in my avatar has never seen any light other than LED, every photo loaded to my gallery has been LED from germ to harvest except for the Reclining Buddha and kali-mist pictures as they were done under t5's and HPS

Edited by GGTBod

Share this post

Link to post

This is your thread, Bod, so you're welcome to politely tell me to piss off if I'm butting in, but I have a few photos of seedlings started under LEDs which might be relevant. They were very healthy & squat with no spindliness or stretching. Poor photography gives them a much lighter green appearance than they actually had.


1 person likes this

Share this post

Link to post

I was so close to getting an LEDs but this board helped me see the HPS light.

There's no doubt LED's are good, what changed my mind was a) the price b) as I will be doing a loft grow I need the heat from the HPS c) the actual light/lumens.

i reckon Lumigrow make LED's as good as any HPS but not many of us have £1400 (equivalent to HPS600) to spend on lighting alone.

It'll be interesting to see the developments over the next couple of years, as they are not far behind and there will be a massive switch soon -maybe worth buying shares in the company if it floats.

Good luck and keep posting your developments.

2 people like this

Share this post

Link to post

I'm just buzzing everyones talking about it, part of me thought i was just in for a storm of abuse, i am really looking forward to the further advancements in this field, I couldn't use my HPS in the space i am at the minute :headpain: with one of those cooling unit reflectors i'd have no space left for bud. I love what i used to do with HPS, I couldn't imagine LED being as good at a 2m tall sativa for example :smoke:

Your seedlings look very happy mate, do people go on like that here all defensive and abusively territorial over their thread??? I better watch my step some ganster might kick my digital arse. I was gonna post some of my seedlings into the thread but i got lost somewhere between half watching Avengers in a box on the corner of the screen and reading around the site, instead i loaded a mix of pics using hps or LED separately into the gallery

Share this post

Link to post

Hey podencoid, which led's are you using/did you use on the seedlings?

Ive avoided the UFO's but cant recall why, possibly from pre-millenium led ufo junk..?

Even though they're CREE based, mine were overpriced & 4 out of the 6 have been sent to places other than the twice agreed upon destinations.

The customer 'service' is also horrendous, and from a dutch firm too... i expected a LOT more in the helpful dept.

Right now i'm being forced to claim compensation for lost / non-delivered goods rather than them send what i ordered to where i requested...etc..zzz

So i'm back looking at aliexpress again, seeing whats hot n whats not.

right now i'm at the point where i think reds, whites & blues are all that are really needed... Maybe multiple red w/lengths & multiple blues with warm AND cool whites,... still unsure but these are the main providers of what the plants desire/require.

Edited by eurasian_farmer

Share this post

Link to post

When I first found this site, everyone scoffed at LEDs, and anyone coming here talking about how good they were got accused of working for the company that made that particular LED!

Since then, a few members have tried and are having success (Vince comes to mind). It seems to me that the current thinking is that growing under LEDs is definitely possible once you understand their strengths and weaknesses.

I'd like to know more about what distance you keep the panels from the canopy, because I've read that they have to be very close, but I've also read that you have to increase the distance over what it would be with a HID! :wallbash:

What is your experience with the panels you use?

Natty :afro:

Share this post

Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
Followers 0