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Growing cannabis easily with LED grow lights. Expert home grower tips and advice.




LED is now starting to become a mainstream alternative to HPS.  Although the initial purchase cost of an LED is still higher than an HPS, the ongoing running costs are lower. LED produces less heat than HPS and this affects many aspects of plant maintenance and grow room design.  

Orange hill special


  • Growroom heat levels are totally different with LED.  A 600W HPS bulb wastes around 450W (75%) of the electrical energy producing heat.  A good quality LED light with a 400W power draw would produce around 200W of heat despite having the same productivity as a 600W HPS.  So the best LED’s only produce about half the heat of an HPS.  For some growers that will allow a significant simplification of the grow room, such as no air conditioning in hot climates.  Other growers will be able to turn down air extraction rates or use smaller extraction fans.  Traditionally many cannabis growers fight grow room temperatures, their grow rooms usually running 3 or 4ºC above the optimum point. With LED grow rooms run naturally at a cooler optimum temperature.  Why waste electrical energy to create excess heat from HPS lights only to have to pay a second time to remove the heat.  LED is a better solution.  



  • Calcium and Magnesium deficiency.  LED lights usually produce much less heat than a HPS light of comparable productivity.  The lower heat levels from and LED means the leaves of a cannabis plant generally transpire (evaporate) less moisture under LED compared to HPS.  The transpiration differences mean that Calcium and Magnesium ions can be less mobile under LED and this may cause deficiencies that you will have to correct with nutrient additions.  You may not notice this issue since soil (and many grow nutrients) already contain adequate levels of Calcium and Magnesium.  Calcium/Magnesium supplemental nutrients are widely available in any grow shop.

Think Different

  • Plant bleaching.  LED power levels have been increasing significantly over recent years, and at the same time so have the LED efficiencies.  Early LED’s would convert 15% of electrical energy to light energy, now the best LEDs convert over 50% of electrical energy into light and that figure is rising.  When light levels are too intense the tips of the plants are bleached, they look white instead of green.  This can be a sign to raise the LED lights higher, or to tie down the tallest branches of your plants.  

AutoDurban Poison

  • Achieving the correct hanging distance.  These days LED is very powerful and hanging distance will play a large role in the performance.  The most common mistake we see is when LED’s are used a little bit too close to their plants, especially seedlings which can suffer stress if the light is too intense for the first couple of weeks.  One easy solution is to keep seedlings in the tent corner (which may have lower intensity light compared to the tent centre), or just to raise the light and allow the plant to ‘grow into’ the more intense light as it stretches later.



  • Water consumption.  Due to the lower ambient heat levels associated with LED the plants may often show a reduced need for water consumption.  Remember that when watering, since inexperienced LED growers can be tempted to over water their plants which reduces root growth and subsequent plant growth.  Cannabis roots need oxygenation to grow fast, over-watering them reduces root oxygenation and reduces plant growth and yield.

  • Taste and aroma.  The best LED growers have found that the lower levels of grow room heat and the cooler tent conditions with LED is allowing more of the delicate terpenes and flavonoids to remain in the plants tissues rather than being lost to the atmosphere in a hot HPS tent.  Anyone that has opened a tent with mature cannabis plants under HPS light which has been running at high temperatures (e.g. 30ºC) will have smelled the intense aromas that flood out of the plant.  Running your tent cooler with LED allows you to keep more taste and flavour in your buds instead of losing them to extracted air.  

Blue AutoMazar



  • LED lights are small and convenient.  Compare a bulky HPS light with a parabolic reflector to a small sophisticated LED.  The HPS is hot and heavy.  An LED runs cooler, is often small and slim and won’t take up all the space in your tent.  People with small grow tents often find LED is the best/only way to produce cannabis.




The advantages of LED are becoming more and more obvious and this is reflected in their increased popularity.  With each passing year the power and efficiency of LED continues to improve.  They are less expensive to run compared to HPS and run much cooler.  The combined benefits of LED mean that HPS is increasingly looking a dated technology, producing a light spectrum that is not optimised for cannabis and too much heat.  LED, by contrast, does not waste energy producing the useless orange/yellow/green wavelengths.  LED  only uses energy producing wavelength-specific useful light at high efficiency and with minimal wasted heat/energy.  Its a technology you will see much more of in the future.


November 13th 2015
Easy Indoor
Grow Guide

Recent comments (27)

On 16 -05-2016 at 23:36 u John Sloan wrote:
What would I need for light to grow in a 4' (W) x 8' (L) x 8' (Tall). I've been looking at LED Apollo of Gallaxyhydro 600w lights (QTY 2). I am wondering if 4 - 6 lights would be better?

On 18 -05-2016 at 17:09 u Tex Caliber wrote:
I was wondering if "The Ultimate" is hard to Clone? Is there a "Trick?"to clone it?

On 19 -05-2016 at 09:27 u Eddy wrote:
Tex, 18th May. The Ultimate is easy to clone in the normal way.

On 13 -01-2017 at 19:58 u Hustlerman wrote:
Hi. Would 720w of fair quality LED's be to much in an 80cm squared (around 2.5ft) environment?

On 16 -01-2017 at 11:06 u DutchPassionTony wrote:
Hustlerman, 13th January 2017. 720W of decent quality LED sounds more than sufficient for that grow area. Good luck !

On 22 -03-2017 at 18:41 u Randy wrote:
i have 2/ 450 watt led in a 6x6 room with 6 clones. is that enough wattage. Thanks

On 23 -03-2017 at 12:06 u Eddy wrote:
Randy, 22nd March 2017. 900w of actual power draw is probably enough for that room.

On 09 -04-2017 at 22:35 u Java the hutt wrote:
Hi! I have a flowering tent which is 80cm x 80cm and 2m in height, with a 400W (draw wattage) super Helios pro LED. What would be the best method for me to make the most out of my light and space? I try keeping an even canopy but not sure how tall to grow the plants before I start wasting time as the light struggles with penetration through the canopy. Should I just grow large and trim off fan leaves or keep them shorter? Thanks for your response and sorry for the multitude of questions!

On 10 -04-2017 at 12:07 u Eddy wrote:
Java the hutt, 9th April. trying to keep an even canopy in the tent is one way many home growers try to maximise light intensity for the blooming plant. Aim for a medium hight plant, maybe tie down the plants to keep the canopy even. Use google also, you will find articles with useful pictures showing you the options

On 28 -05-2017 at 10:29 u Mike hunter wrote:
LED grow lights are capable of providing a wide spectrum light. This is why LED lights are achieving popularity around the world. For LED lights, it is crucial how to adjust the colour requirements of plant. Otherwise benefits from LED lights can not be properly achieved. Thanks for great tips.

On 07 -10-2017 at 22:06 u Peter galolagher wrote:
just curiouse in the way to grow a 1st grow always wanted but too scared of the heat an smell ,just a bit fkn stupid haha

On 11 -01-2018 at 22:41 u Tommy wrote:
Hello my question is i want to know what is the best between one 1200 watts LED or four 300 watts LED for a better light dispersion

On 15 -01-2018 at 14:13 u Eddy wrote:
Tommy, 11th Jan 2018. Normally you will get more even light distribution from 4 smaller light sources than one large single point light source. It will mean less shadows, and better light intensities from centre to corner of your grow room. Good luck !

On 02 -02-2018 at 08:32 u Brad wrote:
Guys I have just bought a Viparspecrta 300w led light and want to stick 3 Auto Mazar's under it in a perlite/lightmix soil using 20l pots. Can somebody let me know the distances I should keep the light from the plant? How far should the light be from the seedlings? and how far should the light be away from the plants in veg? and how far should the light be from the plants in flowering? Thanks in advance guys!

On 05 -02-2018 at 16:59 u Eddy wrote:
Brad, 2/2/2018. Typically people have them some 75+cm away from seedings, and in bloom a little nearer maybe 50cm from the tops. Good luck

On 09 -02-2018 at 20:28 u PurpleRein wrote:
How many plant can grow in a 5x5 tent usingii (1) 600 & watt & ( 1) 300 watt viper-spectra

On 12 -02-2018 at 09:28 u Eddy wrote:
PurpleRein, 9th Feb 2018. How many plants? depends on your goals, and other things. But with a 300W LED perhaps around 4-5 plants. With a 600W LED maybe 6-8 plants? Good luck

On 05 -05-2018 at 12:29 u Greenlady wrote:
Hi would a 240w LED be sufficient for a 3 x 3ft tent?

On 07 -05-2018 at 10:29 u Eddy wrote:
Hi Greenlady, 5th May 2018. a 240W LED in a 3 x 3 foot tent would be OK !

On 16 -05-2018 at 15:07 u Graeme wrote:
there, i bought a 120cm x 120cm x 200cm tent, my aim is 6 plants ,wold a 600w mars hydro led light be perfectly fine for this inside this size of tent?

On 21 -05-2018 at 09:38 u Eddy wrote:
Graeme, 16th May 2018. Yes, a 600W LED in a 1.2 x 1.2 tent sounds like a great way to go. Good luck!

On 08 -07-2018 at 16:59 u Nathan wrote:
Hi Mate. Ive got a 1.2 x 1.2 x 1.6. Only putting 2 big pots in. Should i go with 1x 600w led or 2x 300w led (one for each plant). As ive seen mixed answers. Thanks in advance.

On 09 -07-2018 at 17:05 u Eddy wrote:
Nathan, 8th July 2018. Normally, 2x300W will offer better coverage and less shadow than 1x600W. This is true of LED, HPS or anything else. One other advantage of 2x300W in your case is the limited headroom (1.6m), again a factor which would suit the 2x300W option. Good luck!

On 31 -07-2018 at 21:41 u Natalie wrote:
I actually have two grow "boxes". One is a 4' x 5'(height) x 2' grow tent and the other is a 3' x 7'(height) x 2' closet. I'm wondering what would be minimal or better lighting for each grow box?

On 10 -08-2018 at 13:39 u Mr.greenthumb wrote:
I want to start with 6 plants in a 10x10x6.5ft grow tent how many led lights should I use? Four 300 watt lights? Two 1000 watt lights? I want to make sure each plant is getting the proper amount of light I feel that due to the height of the led lights from the plant, the range wont be enough for all six plants with two lights. What would you recommend to provide the perfect amount of lights and wattage for 6 plants?

On 13 -08-2018 at 13:24 u Eddy wrote:
Mr Greenthumg, 10th Aug 2018. With around 9square metres to cover, consider daisy chaining between 7 and 9 SolarSystem 550 grow lights and control them all from a single hand controller. Each light uses 400W of electricity on full power, so somewhere around 3kW total draw. That would allow you to control power and spectrum. It's always better to have several smaller light sources to give even illumination and minimise shadows. The lights are here https://crazy-leds.com/solar-system-550-led-grow-light.html

On 27 -08-2018 at 19:52 u MadMatt wrote:
I've got two 300w Led lights, I've just experimented my 1st crops, playing with the light source & strains. I used to grow in Holland Using MH & HPS with great results. Led is a learning curve, yet I've got a far better idea on my new 2nd crop. In order to keep the nodes near and compact, I find the lights perform best near the plant, as I found out. In total I took 4 1/2 months, with varying yields, not impressive yet Strong. Perseverance with soil, perlite & nutrients, & ph level of

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Dutch Passion advise their customers to reassure themselves of local applicable laws and regulations before germination. Dutch Passion cannot be held responsible for the actions of those who act against laws and regulations that apply in their locality. Cannabis seeds should be kept as collectible souvenirs by anyone in an area where cultivation of cannabis is not legal.