There are 3 types of Grow lights.
Here’s which one to use:
The important Growers rule: Light = Weight!
CFL Grow Lights
Easy to use, for an alright harvest with not too much electricity used.
- 2700K = Flowering, 6400K = Growth
- Not as much light as HPS lamps, but easier to use and not as much heat
- You can mix 2700K + 6400K and use it through whole grow period
- Keep them close to your plants for best results
- You could use 1 x 2700K bulb for whole grow (Cheap Micro Setup)
- 1 x 150Watt is ok for 2 – 4 plants
CFL Lights are relatively inexpensive. They are easy to use, just plug them into a timer and then the outlet.
They don’t produce too much heat and thus don’t require much ventilation.
And yet, they still yield impressive results.
Available in different colors. 6400K for vegetative phase and 2700K for Flowering.
For a very small setup, just one of these in 2700K with a reflector will do for the whole plant life.
You can get good results by using 1 x 2700K and 1x 6400K at the same time.
Pics of Weed grown under CFL Light:
HPS or MH Lamps
High Pressure Sodium or Metal Halide bulbs deliver fantastic light for Cannabis.
But, they are becoming outdated.
These lights are a bit like a 70’s muscle car.
Quite powerful but uses heaps and heaps of gas.
These lights use lots of electricity but deliver a very good harvest.
Cheap to buy!
You’ll save money on initial purchase, but over time you’ll pay more for electricity.
(Compared to a good LED light which I’ll talk about next)
- HPS can safely be used for veg and growth phase
- MH = Growth phase only
- These produce more light than CFL
- Produce heat. Ventilation needed
- 1 x 400W HPS is good for 6 – 8 Plants
For better quality get a DIGITAL system. Listed here.
These lamps come with a Ballast to run them. Do yourself a favor and get one with a digital ballast. They use less electricity, produce more light and the bulb lives longer. Also, they throw less electro-smog. So the digital ballast is very recommended as opposed to the old dirt magnetic ones which are still being sold every now and then.
I recommend 400 Watt. It produces lots of weed while not overly stretching the electricity bill.
Pics of Marijuana Grown under 400 Watt HPS:
Marijuana Grown under HPS lamps looks a bit more “Professional” than the same grown under CFL It is denser and has more volume.
HPS and MH Lights can be bought on eBay here.
LED Marijuana Grow Lights
Led Grow lights can produce great harvests.
- These can produce great results with little electricity
- Produce little heat
- Fake units very commonly sold. Watch for original brand LEDs (e.g. US made CREE)
They are still expensive, but use very little electricity.
Currently, a lot of people sell these with outrageous claims like :”Replaces 400 W HPS” … or so.
That is most often not true. Especially cheap ones on eBay, they don’t really work.
LEDs have big quality diferences. Additionally, brand names are widely faked.
Genuine CREE LEDs seem to be the best. But, they are often faked. It’s important to check the sellers reputation.
Underneath are links to an eBay seller who seems to produce LED grow lights himself. I trust his lights to be genuine.
Also, I have found a remarkable LED Grow light from an engineer in Holland. His name is Hans and he builds, in my opinion, the worlds best LED Grow light.
It cost as much as 4 large HPS lamps. So it is a bit like a Rolls Royce car. It uses quality LEDs and has a switch to change it from vege to flowering phase.
The best I found –> Hans’ LED Light
fantastic quality, switchable for vege and flower.
Bit difficult to buy from Hans but worth it.
Marijuana grown under Hans 160 Watt LED Light
Marijuana Grown under 160 Watt LED Grow Light
This grow yielded 3.8 ounces (110 gram) for the price of $15 electricity.
2 LED grow panels with 80 Watt each. No big fan required because there is not much heat.
LED Panels are modern, silent, cold, beautiful and energy efficient but expensive on initial purchase.
So which Light is best for me?
If you are on a small budget, or have only little space available, or just want to grow a little weed for yourself: Use CFL Lamps. They are easy to use, inexpensive and produce decent results.
If you have a bit of space available, like a pantry or your garage, you could go for HPS Lamps. They produce big, but you’ll need a fan to get rid of the heat and may also need to filter the smell with a carbon filter. Read more about building a grow box, if you like.
If you are settled and have mastered the game of money. Or if you are generally into new and fine things, try Hans LED panels. You’ll have a silent grow box that uses little electricity and yet produces big yields.
Cannabis’ 18/6 or 12/12 light schedule
When you grow cannabis, you will put your plants initially under 18 hours of light. For the remaining 6 hours they need total darkness.
This 18/6 hours period is called “vegetative stage”. The plant thinks it is spring. It puts its energy into leaf and stem growth. It will not develop buds.
After 2 – 4 weeks of vegetative growth, you are going to switch the light to 12 hours on / 12 hours off. This will make the plant think that it has become middle/late summer. Time to develop buds!
If you have decided to use different light bulbs for vegetative / flowering stage, now is the time to change them.
If you want to avoid stress for your green friends, don’t switch the light radical from 18 hours on to 12 hours. Go 2 or 3 days with 16 hours / 8 hours and 14/10.
Switching on and off is done by a timer. Not manually. Because otherwise one is likely to forget about it.
Grow Light in more Detail: Light Color
As mentioned earlier, diferrent light bulbs have diferrent colors.
Plants in vegetation mode need more blue light. MH Lights provide that. MH lights even deliver some red light which makes it possible to use them over the whole plant life.
Flowering plants need more red light, as supplied by HPS lights.
The CFL Lamps are available in red, blue and mixed colors.
Light Color (also called light temperature) is described in Kelvin. 2700 K is a very red spectrum for flowering. 6400 K is a cool blue/green light, as needed for growth. There is also 14.000 K available which has even more blue.
Light Color Temperature Table
|Used for||Kelvin||Color Name||Color|
|Growing||around 6400||Daylight, Cool||blueish|
|Flowering||around 2700||Warm||yellowish – redish|
Types of Lamps and their color.
There are High Pressure Lamps, Compact Flouro Lamps and LED Lights available. They all have their strength and weaknesses.
High Pressure Lamps
These are the (still) most commonly used Lamps.
Their brightness and good light color bring great results as Marijuana Grow Lights.
However, they also use a lot of Energy (200 – 600 Watt) and produce a lot of heat. Strong ventilation systems are needed. High Pressure bulbs also need a balast to start them up.
High Pressure Sodium Lights (HPS).
High Pressure Sodium Lights emit an orange/red light. Cannabis needs this during the flowering stage.
These Bulbs have a lifespan of ca. 24.000 hours.
Metal Halide Lights (MH).
They send out light in the blue spectrum, which is used in the vegetative (growth) stage of plants.
These bulbs also emit some red. Therefore they can be used for flowering, too. They will yield a good harvest. These bulbs are the best option when you decide to grow under high pressure bulbs.
One disadvantage of MH Lights is their relatively short lifespan of only 10.000 hours.
Compact Fluorescent Lamps (CFL)
A very inexpensive but good option is the use of Compact Fluorescent Lamps (CFL). As shown on the left.
The bulbs are fairly cheap. They do not need a ballast. They run relatively cold
One Lamp with at least 100 Watt will be enough for 1-2 plants. Better use 2 CFLs.
They are available in diferrent colors for vegetative (6400K) and flowering stage (2700K). I had success even with using only one flowering bulb for the whole plant life.