Which Grow Light Is Best for Growing Cannabis Plants?

Growing Cannabis plants indoors is a sweet science that combines lights, growing medium, good genetics, and plenty of fresh CO2 rich air. With so many brands offering various types of Cannabis grow lights. It can be difficult to know the best options for growing Cannabis indoors, so in this article we break down the different types of lights traditionally used. The difference between P.AR and lumens, as well as mistakes to avoid when growing Cannabis.

Compact Fluorescent (C.F.L)

C.F.L’s have been around for decades and will probably be the most abundant light in your household. These low-powered and energy-efficient lights are available in two wavelength spectrums. One is blue / white light at 6400k designed for the vegetative phase (18/6) and the other is red at 2700k designed for flowering Cannabis plants. It is possible to grow good quality buds using compact fluorescent; however, the yields may be far less superior to any other type of Cannabis grow lights.

High-Pressure Sodium (H.P.S)

For the longest time, an indoor grower would typically work with H.P.S grow lights as they were cheap, easy to set up, and only require a ballast to power up. The only downside to using high-pressure sodium grow lights was how much excess heat they would produce, and the spectrum provided was questionable compared to L.E.D lights. H.P.S grow lights will come in 400w, 600w, and the most popular among indoor growers is the 1000w model.

Metal Halide (C.M.H)

Metal halide lights are normally used in car parks or football stadiums for their clear white light they produce. When used during 18/6, these cannabises grow lights will offer the best spectrum for vegetative plants. It will produce a more bushy and more compact canopy compared to H.P.S and C.F.L. Many old-school growers have worked with metal halide and high-pressure sodium together in the same room to benefit from the combined spectrum both lights can provide.

P.A.R and Lumens Explained

In the old days, indoor lighting was widely populated by high-pressure sodium filled grow rooms with the impression that the brighter the bulb, the more efficient it was. That was true in the sense of the lumen rating provided by the manufacturer. For example, a 600w H.P.S will produce 80-90,000 lumens, which would be the equivalent of that many single candles.

P.A.R has now become the industry standard for Cannabis grow lights and will be a conversion of how much photosynthetically active radiation is present at any given moment. An example of a P.A.R rating would be 2.7μmol and 1700 PPF. L.E.D grow lights will normally explain the efficacy of their lights using μmol and PPF and is the value you want to know over lumens.


One question we often get asked at Nirvana is which Cannabis grow lights are actually better? H.P.S or L.E.D? In our professional opinion, we believe that L.E.D grow lights are far superior as for spectrum and intensity for growing Cannabis indoors. However, there are pros and cons to H.P.S and L.E.D, so the final assessment should be made based on your requirements and your budget.

Pros and cons of using H.P.S for growing Cannabis indoors

• H.P.S are reliable and have been used consistently for decades by indoor growers.

• They are a cheap alternative to expensive L.E.D grow lights.

• You can easily fill a room out with H.P.S lights with a small budget.

• The wasted heat energy produces by the ballast and bulb can be very hot.

• For vegetating Cannabis plants, they are not the most efficient.

• The spectrum produced is not as effective as L.E.D.

Pros and cons of using L.E.D for growing Cannabis indoors

• L.E.D can produce a much more effective spectrum for both 18/6 and 12/12.

• The heat output is much less significant than compared to an M.H or H.P.S bulb.

• L.E.D lights can use heat sink cooling, meaning no internal fans are present.

• The initial investment and return on investment may be too much for many growers.

• Beware of cheap imitations and always search for the company spec sheet.

3 Mistakes To Avoid Using Cannabis Grow Lights

If you are new to growing Cannabis indoors, and have most of your equipment checklist covered, it is important to consider a few things before buying your grow lights. Below are some mistakes to avoid and bad habits that you do not want to develop.

1) Low Intensity Lighting:

Indoor Cannabis plants thrive under intense lighting and will produce the biggest and best looking, smelling, and tasting flowers possible. If you choose to use H.P.S, then avoid using 400w high-pressure sodium lights as these will only yield small-sized buds and stick with 600-1000w.

2) C.F. L’s For 18/6:

When it comes to seedlings and clones that require soft lighting, then compact fluorescent work very well. Once the Cannabis clones and seedlings reach a certain point of maturity, then avoid using C.F.L for anything else than a starting point and switch to H.P.S or L.E.D for flowering.

3) Checking for Lumens

Lumens are a measurement of light that is created as a reference for the human eye. Cannabis plants rely on the P.A.R levels which will indicate how much red, blue and white light is present and the spectrums the plants require. The brightness of a growth bulb should not be a way to calculate the efficacy of the Cannabis grow lights.

Nirvana Seeds Conclusion:

In an ideal world, every indoor grower would choose to have the very latest technology and most expensive Cannabis grow lights, however not everyone can afford to fill a room with high-priced lights. As long as you understand the lighting spectrum that Cannabis plants require at the different stages of their life cycle, and can provide them with the intense quantity they prefer, then it is easy to grow high-grade flower and large yields as well when it comes to growing Cannabis indoors.