Best lighting for indoor cannabis growing

Grow lights for indoor marijuana growing have been changing lately due to technological developments in lighting and due to discoveries of how different light spectrums are used by cannabis plants.

Simply sticking a bright light over your plants for the duration of their grow and flowering cycles is longer seen as adequate. These days smart indoor marijuana growers will use different types of lights at different stages of the plants’ growth.

We’ll look at these newer grow lights for indoor marijuana in a minute. But to start, let’s take a look at the old standby lights that still many growers use – perhaps because its easier to use what you know than to contemplate change.

Though if you already know you want LEDs, scroll down a bit for information about these.


HIDs (High Intensity Discharge Lamps)

high pressure sodium grow lights hpsMost indoor marijuana growing gardens used to use High Intensity Discharge (HID) lamps. The two types most commonly used were Metal Halide (MH) which produce an abundance of light in the blue spectrum promoting plant growth.

The other kind are High Pressure Sodium (HPS) lamps which emit an orange-red glow triggering hormones in plants to increase flowering/budding.

The problem with HID lights is that they consume a lot of electricity for output, produce high operating temperatures, and produce a wider spectrum of light – much of which is not needed or used by the plants. In other words, HID lights are expensive to run, inefficient and a potential fire hazard.

That not to say that HID lights, if used properly won’t deliver great results. They most certainly will. But when you figure in the factors of cost and safety, the newly developed fluorescent grow lights as well as the most recent kid on the block, LED lights, have clear advantages.


Fluorescent lights (CFLs, Compact Fluorescent Lamps)

cfl lights indoor marijuana

125w cfl

High powered fluorescent lights are now specifically produced for indoor gardening. They are available in 2 types – Blue 6400K that emit the wavelength of light needed for plant/vegetative growth, and Red 2700K that emits the right wavelength of light for flowering growth.

To produce great crops of marijuana you’ll need both these minds of lights – more of the ‘blue’ wavelength for the first two months and then more ‘red’ when it comes to the flowering phase.

Unlike HID lights, no light falls outside of the needed spectrums which results in less waste and better growth for less power consumption.

With the development of CFL grow lights, HID lighting has been largely replaced.


LED (Light Emitting Diode) lights

best lighting for indoor cannabis growing

LED lights

The development of LED lights are increasingly being considered the best investment for indoor growing. This is partly because of their performance (in terms of versatility and efficiency) and also the huge saving in electricity running costs.

They’re also cooler, so you’ll have no worries about overheating your precious plants.

One of the main advantages of LED lights is the different colour spectra you can create with them. Since plants require different wavelengths (colours) of light at different stages of their growth, using good LED lights allows you to tailor the lighting to the growth stage of your plants in order to maximise your yield.

Some LED lights allow very fine-grained adjustment of the colour spectrum. Others have a more standard ratio of red and blue wavelengths (e.g., about 3 to 1), one which is considered good for all round plant growth.

Other advantages of LED grow lights

Other advantages of LED grow lights are the fact you’ll almost never have to replace a bulb since most of them last for 50,000 hours or more. This is roughly equivalent to having them on for 12 hours a day every day for ten years. So there’s a cost-saving right there.

The other advantage, as mentioned above, is that LED lights give out much less heat than any other lighting. With good quality LED lighting, you can even dispense with ventilation and fans (again, more cost-saving).

In summary, good LED lighting will save you a lot on running costs. And if you get the kind with an adjustable colour spectrum, you can really max out your yield. Thus getting bigger plants and greater yields for the same seeds and grow space.


If you’re thinking of using LEDs, do a bit more research to find the best ones for you,  bearing in mind that good quality LEDs are pretty pricey. On the other hand, they can give you the best results. For example, Kind LED lights have now won several awards for their excellent efficiency and performance – more information on them below.


So what is the best lighting for indoor cannabis growing?

If you have the money for the initial outlay, LED lights are generally the most efficient, the most effective, and the cheapest to run.

However, LEDs are the most expensive to buy. So if you don’t have the grand or so it might cost you, CFL lights are the next best choice. They’re the next most efficient to run, in terms of performance, electricity costs and bulb replacements. You can also do a limited bit of colour/spectrum targeting by using red and blue spectrum CFLs.

HID lights are the old standby for indoor growing gardens but due to the advancements in CFLs and LEDs, HIDs are now largely a thing of the past since the high power consumption, high heat generation and general inefficiency no longer makes them a viable option.



In short, if you’re the experimental type who likes to be on the cutting edge of technology, LED lights are the top choice – especially if you’ve got some extra coin to invest.

Otherwise you can’t go wrong with specially designed CFL grow lights. Power consumption and start-up costs are reasonable. Good performance is well documented.

Here are some links to top of the range award-winning LED lights, as well as a cheaper LED light, and some good quality CFL lights. Take your pick!


Selection of CFL grow lights on (UK)cfl grow light cannabis uk

click on the image to see specs, prices and availability

125-300W CFL grow lights, around £20 each




LED lighting for indoor cannabis growingCheap LED grow light – (worldwide delivery)

Lighthouse Hydro BlackStar Flowering LED Grow Light, 135-watt, $179.95

(recommended by some growers as a good one to start with if you want to do a very small grow under LED lighting)



Expensive but award-winning LED grow lights – (worldwide delivery)

best lighting for indoor cannabis growing - Kind LEDsKind LED lights, from $660 – $1895 (about £540 – £1550)

Fully adjustable 12-colour light spectrum, built-in timer, remote control (on some models)

Winner of High Times “Gear of the Year” awards several years running!

(Click on the picture for more information and/or to order.
Or click here to read our review: Best LED grow lights)


A few tips on using CFL grow lights

During the vegetative phase, the plants should be given 16 to 20 hours of light per 24 hours. (This is usually the first two months, depending on the strain.)

Some say you should grow your crop longer before inducing flowering as it results in a better more potent crop. But of course it depends to a degree on the strain. And opinions differ even among growers of the same strains.

The length of the periods of light should be reduced to no more that 12 hours every 24 hours when shifting to flowering period (which will usually last between 8 and 11 weeks depending on strain).

The plants will continue to grow in the flowering phase and can easily double, or even triple in size.


Using UVA and UVB lights for indoor cannabis growing

“The Dutchman” grower is experimenting with using UVA and UVB lights. He claims they are the best lighting for indoor cannabis growing if you want to increase the potency of your crop. For how to do this, watch the video here.

And to get the grow lights he recommends – 4 ft Zoo MedReptiSun 10.0 UVB/UVA Bulbs –  click here:

UVA-UVB lights by Zoo Med on

UVA-UVB lights by Zoo Med on


Good luck with your grow!