A grow light is a artificial light used by growers to provide lights to plants in indoor spaces, they can also be used to add additional lighting to outdoor crops in green houses and poly tunnels.The idea behind a grow light is to provide plants with a spectrum similar to natural sun light or more specifically a spectrum that is of use to plants.
There are many lights available to grow a whole range of plants. In this post i will focus on the types we as ganja growers use to grow the glorious herb!
Cannabis plants require different spectrum's of light for different stages of growth, as well as different intensities of light. For example, a cannabis plant in the vegetative stage of growth requires more blue light, a plant in the flowering stage will require more red. The beauty of this is plants needs is that it has created many different types of grow light to be used. Each has its own pro`s and cons, each has reasons for and against using. These will vary from set up to set up and individual growers needs.
Grow lights usage
Grow lights have been around for a long time. They are not just used by us ganja ganja growers. They are used to grow food and crops worldwide in indoor environments and as additional lighting for outdoor crops, this means the development in grow lights has come a long way in recent times. This has produced grow lights in many shapes and forms, no matter what your situation, growing area, growing needs, there is a light perfect for you.
What do we need from a grow light
Many plants will thrive under different spectrum's of light. Mimicking natural sunlight would seem the obvious answer, however plants dont need all the spectrum produced by natural sunlight to grow. More of a specific spectrum/colour will promote better growth in different stages of a plants life.
Lights with more Blue spectrum:
Cannabis growers around the world have been using lights with more blue spectrum for many years during the vegetative stage of growth. Blue light will keep a plant more compact, promote healthier and faster growth of leaves which is very important. Most of us grow indoors, so keeping a plant shorter and more squat in the vegetative stage means the plant is easier to manage and train easier, while keeping node spaces close together which will help increase the flowers and flower density come flower stage.
Lights with more red spectrum:
Lights with more red spectrum are used in flower. Red spectrum mimics that summer is coming to an end and a plant needs to reproduce. By introducing red spectrum or more of it a plant will produce more fruit, cannabis plants seed factories are the bud we all love and grow for. So increasing the red spectrum in this vital stage will promote greater yields.
Mixed colour spectrum:
Going by the above 2 examples of what colour spectrum to use at different flowering stages seems clear cut, it isn't. There are differing opinions on whether blue for veg, red for flower will produce the best results. Many growers will use a mixed spectrum grow light for the veg and flowering stage, others will use a predominantly blue light for the entire grow, other a predominantly red light for the entire grow. There is a strong argument for all aspects, the biggest of all being whether a plant should have the full spectrum it needs at every stage or the specific spectrum's best suited to each stage of growth.
Light types, usage and pro`s and con`s
Here i will list the main types of lights used to grow cannabis, there are more but we will stick to the most commonly used lights for indoor growing.
High intensity discharge lights
There are a few lights in this category, and some are the most commonly used lights in indoor cannabis growing. HID grow lights produce a high lumen to watt efficiency and are very intense offering great penetration of a plants canopy, this means more light will reach lower plarts of the plant. HID lighting is very good a replicating the spectrum of natural light.
Metal Halide (MH):
Metal halide bulbs produce more blue spectrum. This is closer to the light plants outdoors will receive naturally in spring. Metal halide produce the correct spectrum to promote fast healthy compact growth, strong roots and resistance against decease. All of these things give a plant a good start and build the perfect structure to get the best of your plant once you are in the flowering stage. Common sizes used for MH bulbs are 250w, 400w, 600w and 1000w.
Lumen output of a MH (the below lumen outputs are a guide only, different manufacturers may vary)
250w 13,500 lumens
400w 24,000 lumens
600w 50,000 lumens
1000w 90,000 lumens
Pro`s:
Excellent at promoting healthy roots and growth early in the vegative stage.
Cost effective to set up and use.
Excellent watt to lumen ration.
Cons:
Run very hot. You will need a good extraction system to deal with this heat.
Not the cheapest of the grow lights to run.
Not ideal for the flowering stage of growth. Should be changed or supplemented with a light of mixed or red spectrum.
Ceramic Metal Halide (CMH):
Ceramic metal halide bulbs are the new kids on the block. CMH grow lights are basically a variation of both metal halide and hps. By using new materials in their design they are able to produce a greater spectrum than MH and HPS (the 2 most commonly used lights in growing). They are more efficient and claim to last longer than the equivalent HPS/MH bulbs. The above means these HID bulbs can be used for both veg and flower. Ceramic metal halide lamps are commonly available in 315w.
Lumen output of a CMH (the below lumen outputs are a guide only, different manufacturers may vary)
315w 33,000 lumens
Pro`s:
Greater colour spectrum over other HID lights.
More efficient than other HID lights.
Cooler than Other HID lights.
Cons:
While cooler than other HID lights these still run very hot and will need a good extraction system to deal with that heat.
More expensive than other HID lights to set up.
High Pressure Sodium (HPS):
HPS lighting is the most widely used of the HID grow lights and arguably the most commonly used grow light today. HPS is more efficient than MH. HPS lights produce a more more of a yellow/red spectrum, closer to natural light at the end of summer into autumn. They produce more of the spectrum needed by a flowering plant meaning a plant will produce a better harvest. HPS bulbs are most commonly used in 250w, 400w, 600w and 1000w.
Lumen output of a HPS (the below lumen outputs are a guide only, different manufacturers may vary)
250w 25,600 lumens
400w 50,000 lumens
600w 95,000 lumens
1000w 150,000 lumens
Pro`s:
Have the correct spectrum for flowering plants.
High watt to lumen ratio.
Cost effective to set up.
Con`s:
Not the ideal coulour spectrum for all stages of plant growth.
Run very hot, a good extraction system will be needed to deal with the heat produced.
Dual Spectrum HPS:
Dual spectrum HPS bulbs still produce more red than blue spectrum, but enough blue is produced to enable a grower to provide a plant with enough of each spectrum for every stage of a plants life cycle. They dont produce as much red as a hps and not as much blue as a MH. But are a good in between for growers not wanting to have numerous bulbs for each stage of growth.
Lumen output of a dual spectrum HPS (the below lumen outputs are a guide only, different manufacturers may vary)
250w 33,000 lumens
400w 55,000 lumens
600w 90,000 lumens
1000w 140,000 lumens
Pro`s:
Mixed spectrum ideal for all stages of growth.
Cheap to set up and maintain.
High watts to lumen ratio.
Con`s:
Run hot so will need a good extraction system.
Summary of HID lighting:
HID lighting has grown countless plants over the years, there is a reason it is still the most commonly used grow light today. Issues with HID lighting is mostly the large amount of heat produced, meaning they are not ideal for smaller set ups or large growing areas where a grower wants numerous lights in a area. They are very efficient, meaning you are getting a lot of lumens per watt of electricity used, they come in many types as mentioned above, blue, red and mixed spectrum's mean they can supply the perfect spectrum's for your plants, used alone or mixed. I have given a summary of some lumen out puts to give you an idea of the lumen per watt comparisons between the different HID light, lumens are not everything when it comes to growing cannabis.
Note: Most HID bulbs will loose efficiency over time, the bulbs will need replacing every 1-2 years. In order to achieve the correct spectrum designed by the manufacturer these bulbs must reach certain temperatures. Many growers will buy a 600w digital dimmable ballast and a 600w bulb, dimming a 600w bulb will mean that the bulb is not at the correct temperature and will not be producing the desired spectrum.
Compact Fluorescent Bulbs
Compact fluorescent bulbs have been around a long time. They wre the go to lights for many indoor growers when people first started to grow cannabis indoors. They come in a range of spectrum's, blue, red and mixed. There are 2 main types used to grow cannabis.
Tube style fluorescent lights:
The most common of the tube style fluorescent lights used are T5 and T8 grow lights. They are low wattage fixtures that can be used for seedlings and cuttings. They can also be used for plants in the vegetative phase of growing and keeping mothers but are not efficient and dont produce many lumens compared to other grow lights. Due to the slim nature of the fixture itself and the very low heat produced it is a good solution to very small grow areas, typically where seeds and cutting are started. These lights are availible in a range of sizes and wattages.
Pro`s:
slim profile means they can be used in small areas with little headroom
Low watts mean cheap to run.
Con`s:
Not powerful enough for anything other than early stages of plant growth.
Compact Fluorescent Lights (CFL):
Compact fluorescent lights are still widely used in many grow rooms around the world. They are available in blue, red and mixed spectrum's. There are dedicated grow versions that produce the correct spectrum of light to grow a plant. They run very cool making them ideal for small spaces. They run on low watts so are also ideal for plants not requiring large amounts of lumens, seedlings, cuttings, mothers ect. They are most commonly available in 23w, 42w,85w, 125w, 200w and 300w.
CFL lumen output (the below lumen outputs are a guide only, different manufacturers may vary).
23w 1,600 lumens
42w 2,800 lumens
85w 4,250 lumens
125w 7,000 lumens
200w 10,000 lumens
300w 22,000 lumens
Pro`s:
Varied sizes mean they can be used in small and stealth set ups.
Low heat means large extraction systems are not needed to control heat.
Cost effective to set up.
Con`s:
Not as efficient or powerful as other grow light types.
You will get many more lumens per watt using other types of grow light.
Summary:
While Fluorescent lights have a place in indoor growing they are limited. They are not as efficient or powerful as many other types of grow light available. For low cost small set ups they are ideal, mother plants, seedlings and cuttings. For a full set up there are much better options.
LED lighting
LED lighting was the new kid on the block a few years ago. Unfortunately the early models were not great. The spectrum's were not up to growing a plant properly. Many growers suffered deficiencies and reduced harvest per watt.
That being said, LED lights have come a very long way in a short time. They have gone from strength to strength and new models now include full spectrum's of light and very high lumen output per watt.
There are many types of LED available now, from standard boards using a range of LED diodes, COB light fixtures and focused lens fixtures.
Newer LED grow lights are now using specific diodes that have been designed to grow plant, the future seems bright where LED is concerned.
Pro`s:
Led are now available in full spectrum.
Some models have a very high lumen output per watt.
They come with everything needed, essentially plug and play.
They run very cool.
LED lights have a life rating of 50,000 - 100,000 hours.
Running costs are lower than most other types of grow lights for lumens produced.
Con`s:
LED lights come in range of prices, as with most things you get what you pay for. A good LED grow light will be very expensive.
It can be confusing when buying a LED light, do your research and check reviews.
Some LED lights dont have great penetration.
Summary:
You may have noticed i have not mentioned lumen output for LED lights, this is because they are so varied from manufacturer to manufacturer. For many growers LED lights are the future of growing, for others they are just a fad. LED has many appealing qualities but the price for a decent one, or enough to cover a large area puts them out of reach for many hobby growers.
Plasma Grow Lights (LEP)
Plasma grow lights burst onto the growing scene a few years ago, with claims of full spectrum, longer lifespan and other benefits. The major issue with plasma grow lights is the price, putting them well out of reach of hobby/personal growers. This has a knock on effect meaning that they have not been used/tested anywhere near as much as other newer lighting technologies like LED and CMH for example. Because of this there is little info out there at present. The first LEP lights lacked the power/spectrum for flower, the newer versions claim to be up to the job. Time will tell.
Pro`s:
50% less energy used compared to HID lighting.
Full Spectrum.
Long life span of bulbs 30,000 - 40,000 hours.
Deeper penetration.
Con`s:
Price, these are so expensive they are not cost effective for personal growers, this may change in the future.
Lumen output still isnt inline with MH and HPS.
Untested, again the price is stopping these lights from getting the field testing needed.
Summary of the above grow lights
So....After reading that i hope you have a better understanding of the numerous lights available to us growers. We have lights for every set up, style of growing or budget. Of the above lights the 2 stand outs are HID and LED.
HID has done the job for many years and continues to do so, cost effective to set up, good lumen to watt ratio, you can ask for more from a light. The downside is the heat produced and running costs for larger grow areas.
LED, it has promised great things, until recently it hasn't delivered. We now have dedicated growing diodes being created, the price is still high but not as much as it once was. Low running cost but high set up cost.
Interesting times lay ahead!
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