Jan 252012
 January 25, 2012

bc budWhat Lights to Use For Growing Weed Indoors

Growing marijuana indoors has its advantages and disadvantages just as growing the cannabis plant outside does. Indica marijuana strains are perfect for growing marijuana indoors because of their short and wide plant growth compared to the thin and tall growth of sativa marijuana strains.

When setting up a home grow location its absolutely essential that you choose the right lights at the right growing stages for your marijuana plant. Marijuana plants grow in two stages; the vegetative stage and the flowering stage.

The Vegetative Stage (A)
When a marijuana seed is first planted it enters the vegetative stage where it begins to grow out its stems to prepare for budding and the flowering stage. The vegetative stage can last anywhere from 1 week to about 40 days and requires a standard day light cycle of 18 hours on – 6 hours off for the most effective results. Some growers prefer a 24 hour light cycle for the vegetative stage, which will stimulate quicker and faster growth. Either one should work fine, however, a standard day light cycle may work better for pure Indica weed strains.

The Flowering Stage (B)
After 40 days or a couple weeks (or whenever you want to end the vegetative stage) the light cycle needs to switch to 12 hours on – 12 hours off in order to start the flowering stage, which starts as soon as you switch the light cycle allowing the plant to produce buds. When choosing when to enter the flowering stage, after about a month use good judgment based on plant size and health. For maximum growth most strains can enter the flowering stage after about 40 days as long as the plant looks healthy and is tall enough.

Keep in my mind that different weed strains combined with various growing techniques will produce different results at different times. Some strains may take longer to mature and prepare for the flowering stage compared to others. If you know the exact marijuana strain seed you have its a good idea to look up the average height when grown indoors. This will give you a perfect measurement of when your plant has matured and is ready to enter the flowering stage.

Ok, so now to the point of the article. What lights should I use for the vegetative and flowering stages?

The best lights to use for the vegetative stage would be any kind of fluorescent bulb. This is because the cannabis plant loves tons of blue light in the spectrum which can come in the form of many different fluorescent bulbs which are common for home growers in the vegetative stage because of their low height output and efficient blue hues of light. I wouldn’t recommend using high energy and heat consuming Metal Halide lights (which give off nice blue hues of light) unless you have a license to grow medical marijuana and live in a state where its legal.

When you use lights that consume a lot of electricity, you run the risk of having your energy bill draw suspicion from authorities. Luckily, there’s really no need to deal with anything other than blue hue fluorescent bulbs for indoor growing until you get to the flowering stage. This is where a High Pressure Sodium light would works best (alone or with the fluorescent lights) and you can get away with it because the lights will only be on only 12 hours a day which will consume less energy and heat.

You can see in the diagram below that the cannabis plant requires blue and white light (Metal Halide & Fluorescent lights) for the vegetative stage (A), and red, orange, and yellow light (High Pressure Sodium Bulb) for the flowering stage (B).

Light Spectrum For Growing Marijuana

marijuana cannabis light spectrum

image: howtogrowmarijuana.com

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Note: Metal halide and high pressure sodium lights require a ballast for proper use and may consume a high amount of energy with high levels of heat output.

Get a free guide about growing marijuana at this link here.

Order some high quality marijuana seeds at this link here.

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About Johnny Green

Johnny Green is a marijuana activist from Oregon. He has a Bachelor's Degree in Public Policy. Follow Johnny Green on Facebook and Twitter. Also, feel free to email any concerns.
  • Easy

    I am bringing 4 plants indoors that have nice buds. What simple bulbs and how many do I need 2 put them in my closet?

    • Zack

      i’m on a low budget so i would say CFL 100w or 150w 3000k to 3400k for flowering i think but it could be different. i just know t5 tubes are 3000k.. i do have cfls for my grow box but i’m too tired to go look.

  • nas

    I had bud my plants useing cfl 100w bulbs 10 each and the buds does not have any strength. Can the light be a problem it looks great. But no smell and strenght i need help please.

    • professor Muir

      Check the ph of the soil first and make sure it is around 6.5. If that is good check nutrient content and maybe flush if to high. Then water less marijuana likes it dry and if it is a sativa it will take longer

    • MrMcFreely

      How far do you have the lights from the plants? Floros need to be real close to be affective since they are not as intense as HID’s. Make sure your lumen/sq ft ratio is good. 3000 per is bare minimum. 5000-8000 is better.

    • Zack

      mylar and as he said close to plants but measure to 4-1/2 -5 or 6 inches away so you dont burn the plant.

    • http://www.ExposingTheAgenda.com/ Rob

      How did you determine it was time to harvest? Were you watchimg the trichomes? Or, were you doing something else?

  • allin green

    agro lite xt..the bomb light for colors, lumens & yield!! also useable for not only 16/8 but also for 12/12. my favorite pick!!!

  • Zack

    i would just use hydrofarm t5 6500k and then agromax 3000k nevermind buying another light… i cant afford that. i dont work for many reasons and i’m on disability and the fact i use cannabis for insane joint pain and i will never take pain pills cause i know this is the best for my condition and as said it’s safe. my family isnt as supportive of this as i… they live by false information and never will wake up and smell the coffee. it’s stupid that i hear bs from brother especially.. just said from information from the government that it causes heart attacks but ive never had one in all the years ive smoked it so thats just bs. at the moment i’m out of smoke and i will probly not get any till around christmas and hell i’ll be in alot of pain then and probly in a week or 2 it willl just creep in with a punch.. jeeze!!

    • phrank

      Check out kratom. Non opioid opioid receptor agonist, legal, non addictive(well, sort of), and will help your pain and get you moving. Kratom and kanna kept me from losing my mind as I stopped smoking after geting busted. Don’t suggest kanna its a little risky for some, but kratom rocks. Kratomherbs or kratomnaturals. I don’t like tea, so I use uei. Many extracts are junk.

      • mary

        ok holyer than thou..ok you got caught…you made mistakes..get off here…what you got caught and now your holy…leave real people to medicate there pains with what god gave us..natural medication…natural…

        • phrank

          I’m not sure what you’re taking that you imagine me acting or being “holy”, but its all in YOUR head. Kratom and kanna are BOTH natural plant substances, go do YOUR preaching somewhere else, leghair. And yup, I got caught, but I was as good as any grower in the country, and have solid advice to offer. If you had a brain you’d listen instead o bitchin, these kids are wasting time and effort, apparently without ever reading so much as a high times q and a section. Go grow under a 75w equivelent cfl, dumbass, I won’t waste any more time here.

          • FunkyBrains

            I might as well join in the fun here. Phrank is totally off base and clearly has no actual grow knowledge of using cfl. Maybe it’s just been a while since he grew, like back in the 70’s or maybe he just doesn’t grasp certain concepts. Truth be told, more small lights actually DOES do more good than one large one. Simply put 1 lumen is one lumen. I have had a few successful grows over my time utilizing only low wattage cfl’s. I’m talking big fat juicy quality, its all in how you present it. Just read up and go for it.

  • phrank

    Wow, just wow. Lots of bad ideas here. I got busted years ago and can’t play anymore, but ill fill you in on some good knowledge. First, a whole bunch of weak lights do not equal one bright light. 10 weak cfls at 100w(assuming you mean 100w equivelent) each for flowering is crap, you’re wasting time and energy and giving bad advice. There are much better standard output t5 tube fixtures and 300w equivelent cfls(4000lumens each at 3000k) available if you can’t use a hps lamp. 10 100w cfls use roughly 150w, buy a 150 w hps and stop wasting time(and don’t try more than one or 2 under it). The whole fixture and bulb won’t cost much more than quarter bag of dank, and you ont ever get any dank at all with low watt cfls. Lastly, unless your state is legal, stop seeking advice on line, buy a book, and visit a hydroponic store for some literature. Big brother IS watching you. I won’t lie, I miss it, but a whole night of questioning, watching your love get hauled out in evidence bags, the expense and limitations from court proceedings and probation, al make you feel pretty stupid when you’re caught. Lay low, shut up your bragging, and don’t solicite criminal advice online.

  • Mark

    Still spend $1499.00 for a full spectrum 255w ??? VANQ will tell you how you pay less money, at the same time , enjoy more newest technology of led growing . VANQ latest full spectrum(380-780nm) COB 300w led grow light. the earliest full spectrum led grow light for medical growing . http://www.vanqled.com Skype: vanqled12 email: vanqled12@vanqled.com

    • Den of Earth

      Those lights are 1 watt LED lights. The sweet spot for growing plants are grow arrays using 3 Watt LEDs.

      • Mark

        they are COB 72w grow arrays. consist of 72pcs 1 watt on one array. with phosphors full spectrum.

        • Den of Earth

          You won’t get much depth penetration of light through the canopy with 1 watts led arrays. You need 3w led arrays to get the depth penetration for decent flowering. Those lights you are pushing are over priced junk.

          • Tang Mark

            Well , let’s say people hobby difference . We have one customer in Holland , professional grow shop seeking for a totally great led grow light for marijuana, i know it’s also growers looking for . it’s a super large market . before that he has test many led grow lights, but no would be satisfied.
            this time, he prepared a fully perfect test condition,many testing machines import from US, Germany ,China ,and do the test in Vienna Austria with 300W 7band from May to July , more than three month passed , the outcomes seems sweet . what his one words impressed me most is “none of this LED could beat a 300W Vanqled”, this is his original words. I really appreciate all the awesome work my buddy has done for the testing . after that , he will do very aggressive promotion in the Whole Europe.

          • alf Jahag

            Listen you silly little girl, those 1w diodes are barely 2mm together they are on 1 big diode, and it’s all packed together under 1 optic lense, not some big lumbersome peice of plastic. So what is better? 3w diodes placed half inch apart or dozens of 1w placed onto a diode only 2 inches square?. Think about it next time den comes back down to earth..

    • Eggy

      Exactly mate, dizzy fools still rocking foot long panels with infinitely doubtful performance, when they could have all that power and penetration in 1 big super powerful diode. Vanq bitches van rucking Q..

    • Tang Mark

      and now 600W(4X150W) COB LED Grow light available , full spectrum 380-840nm imitate the sunlight. super intensity and high lumen which would solve the problem now usual grow lights facing.
      80lm/w , actual power more than 572.76W , all those main data most manufacturer can not achieve. i believe it’s a revolution for modern growing ….

  • ZackDaddy

    hi im growing my own strain of marijuana and am currntly using an LED lamp called desk-brite to grow during the vegetation stage and was wondering if i need brighter lights or higher watts for my lights just for veg. stage. please help me i cant find this anywhere on the internet also i’d like to know how much watts are in these desk-brite lamps?

  • alf Jahag

    Fucking A, VANQ my friends VAN fucking Q. They do a 75w full spectrum 380-840 nm phosphor LED for only £20, and a 100w for £29, power supplies are cheap as shit of ebay auction and buck boost to help precisely control voltage and current are also peanuts. It cost me £50 for 2x their 72w 7-spectrum chips and only £33 for a 100w version including power supply and regulators, so that’s £80 for 240 actual watts of LED power, add an optic lense and your rocking dense buds. Fuck kessil, bysen, hydro grow and the rest of them capitalist rip-off sellers who charge £250 for barely 200w of power on a peice of plastic over 1 foot long, this is why growers still doubt LED effectiveness. You can have all that power in a diode barely 2 inches square, vanq bitches check em out on aliexpress, especially their ground breaking full spectrum 380-840 phosphor.. do iT..

  • alf Jahag

    Yes vanq on aliexpress sell very high PAR chips with multiple 1w LED’s in a matrix barely 2 inches square, the penetration is sick, and the price sells itself, around £25 for 72w chip and £33 for 100w, they have 7-band (660,630,440,470,600,380,730). Not those doubtable big-arsed plastic panels that Look cheap and fail if 1 diode dies and takes the whole unit with it.. Bysen charge over $1000 for their full spectrum 380-850 nm chip, but vanq sell it much much cheaper.. Sound good then type VANQ led into Google and see for yourself.. Vanq ladies van bloody Q..

    • Tang Mark

      you awesome guy know the key for the grow leds. appreciate….

  • JoeGrow

    Cool White fluorescent bulbs are full spectrum.

  • anonymous

    i just need more money my job pays me shit. what is the cheapest way to grow a few plants in my closest without all this technical crap?