A Comprehensive Guide to Grow Lights – EverythingGrow

A Comprehensive Guide to Grow Lights

There are numerous kinds of grow lights to choose from. If you are a newbie and confused about the best lighting for your grow room, this comprehensive guide to some of the most common grow lights could help you get past the confusion. Let’s get started!


LED Grow Lights


Let’s start with one of the best! LED Grow Lights are highly efficient and the latest high end LED lights are definitely one of the most remarkable. In case you are planning on growing flowers, we would recommend the high end LED lighting with higher wattage diodes and multiple spectrums, for example KIND LED. There are cheaper variants of LED lights available too, but these are probably just good enough for basic veg growth. These are made using old technology or have a weaker wattage diode. If your plan is just for regular greens, these may be sufficient for your need.


Fluorescent Grow Lights

T5 and CFL


A simple lighting method for the garden that is most commonly used by growers for a veg room. Fluorescent lighting is very efficient and produces much lesser heat as compared to HID lights. T5 and CFL are the most commonly known and available Fluorescent Grow lights.


T5 is recommended for indoor garden spaces. These all inclusive lighting systems need no external ballast and also comes with inbuilt reflectors. Most come with preinstalled bulbs and offer either a grow or bloom version. If you want to maximize your T5 veg lights, PowerVEG Tube, by Hortilux is the newest and first indoor gardening specific T5 bulb. It costs much higher than regular T5 bulbs.


CFL is also used for indoor gardening but are usually smaller 25w medium base socket or 125w CFLs. It is highly recommended to trust industry specific lighting systems rather than purchase one off retail stores and markets. CFLs specific to indoor gardening are self ballasted so all you need to do is install it to a CFL reflector. Most CFLs available off retail stores are not self ballasted and majorly for outdoor spaces.


Fluorescent grow lights are simple and produce less heat resulting in less usable plant growth specific light and less light penetration. While it is perfect just by itself for veg growth, it can also be used as an additional supplement for flower growth as it offers lackluster results if used as the primary source for flower growth owing to its less light penetration. If you insist on using fluorescent lighting for flowers, we would recommend a canopy method of growing for better results, as it will help maximize your lighting and reduce the need for light penetration.



HID Grow Lights


HID lighting comes in 4 variants; each unique and specific. Firstly, certain bulbs are referred to as lamps in the lighting industry owing to the fact that they use gases to burn instead of a filament. Let’s take a deeper look at each of these variants:


1.     Metal Halide(MH) or High Pressure Sodium (HPS) Lamps


MH and HPS are both HID grow lighting systems. All HID lights need a reflector/fixture, a bulb and a ballast. All these parts are separate and need to be put together for use; sometimes fixtures may be available with a ballast.


For the vegetative or growing stage of plants, MH lamps are most recommended. These produce a blueish yellow spectrum that promotes the plant growth at this stage. On the other hand, HPS lamps are recommended for the blooming/budding stage of plant growth, as the red/orange spectrum promotes the growth at this stage. Thus, depending on the stage of your plant growth you can switch between MH and HPS lamps to enhance the growth. In case, you need to choose any one, HPS is recommended as the blooming yield is the prominent stage of plant growth. These lamps are low on energy efficiency as they produce very high heat as compared to LED or Fluorescent lighting systems. However, these are much more affordable than LED growth lights and produces better usable light than Fluorescent grow lights.


2.     Dual Arc Lamps


This is another variant of HID lighting type. Technically a HPS, it contains both bulb type components that give a more natural and a better spectrum. To elucidate further, a 1000w dual arc lamp will be a combination of 600w HPS and 400w MH component.


3.     Double Ended Lamps (DE)


In a DE, voltage is generated at both ends that result in better and even burning of the gases within the tube. It also has a better stable spectrum output that increases the light intensity by 10% and the PAR output is increased to, as compared to HPS. Also, the UV and IR emitted is much higher. These kind of bulbs have a slower rate of degrading and as a result they produce 90% of the original intensity even after 10,000 hours. These kinds of lights require the three traditional components like the HID lighting, lamp, reflector and ballast. It is also commonly available in the all inclusive ballast units as compared to MH/HPS light systems.


You cannot use traditional HID hardware for DE. These require specific DE reflectors, DE compatible ballasts and specific DE grow light bulbs. Since most De reflectors are open and don’t have any cool ports or glass it is necessary to plan the grow room setup with open reflectors to use DE. The glass filters out a huge portion of the UV and IR that the DE gives out and as a result the air cooled DE works much better in comparison to HPS grow lights. We highly recommend a change of setup before going in for DE grow lights.


  1. Ceramic Metal Halide (CMH)

These grow lights are also known as LEC or CDM lights. These are the latest technology in the world of grow light types. With a highly broad spectrum and the ability to emit UV, it is the closest to natural sunlight as compared to HID lamps and lighting systems. These are most recommended for veg growth, SOG application or as an added supplement full spectrum for large grows. CMH is far more efficient than traditional MH and have a higher PAR to watt as compared to HID grow lights. These have a longer life span too and can give up to 24,000 hours! Most people believe it is necessary to include the Color Rendering Index rating for lamps to measure plant growth but in fact it is not required at all. Nevertheless, CMH lamps lie between 80-95 CRI range.

Similar to DE grow lights, CMH grow lights use open reflectors and are generally all inclusive units. It consists of a bulb, reflector and ballast. These too have a special socket just like the DE and need a special reflector and ballast. Even though some have been successful with flowering using CMH we still recommend a 1000w or 600w HPS for the same.


Now that we have gone over the different types of grow lights and made basic recommendations based on individual and specific needs, let’s run through a basic comparison between the various Grow Lights to understand the use of each according to different stages of plant growth.


Grow Light Comparison Based on Plant Growth Stages


HID vs LED vs Fluorescent


HID has been, and continues to be, the most popular amongst the different grow lights. Owing to the higher energy efficiency and advancing technology, both Fluorescent and LED grow lights are now gaining popularity as well. More and more people are understanding the differences and varying nature of different lights and the fact that HID grow lights, though cheaper to procure, produce very high heat and consume immense amount of electricity resulting in higher electricity costs, along with the added equipment cost like A/C. to understand the difference between the three, we’ll divide the use according to the different stages of plant growth.


-       Seeding


During the seeding or clones stage, the plant does not require too much light. The minimum light that it does require cannot be too intense either. We highly recommend using fluorescent grow lights at this stage, which also happens to be the most commonly used light by growers. Our recommendation is based on the fact the fluorescent lights produce just the right amount of light for the plant to grow at this stage. Additionally, the light produced is not very intense and will not damage the plant or produce heat it cannot withstand. Apart from fluorescent, LED grow lights are also commonly used at this stage. But one needs to be sure of using only the basic type of LED grow lights that would fit in the normal household socket and not use the K5 series or KIND LED grow light types.


During the seeding and clones stage it is best to keep away from HID grow lights because of the intense heat they produce that can be damaging to the plant. An HID of 150w put 3 ft above the seedling would probably be fine but any closer or higher wattage would be damaging. It’s best to avoid HID at this stage. The most recommended is fluorescent grow lights that are about 125w CFL with a basic reflector. The light hangers would be typically cheaper than a 2 tube of 2 ft T5 and give you more light. You could also source some cheap LED bulbs for specific veg growing and make your own setup.


-       Veg Stage


This is the stage where you require light to be more intense. You may still use florescent grow lights but with bigger fixtures and more number of bulbs. As mentioned earlier the newest T5 bulbs by Hortilux are exceptional for this stage but they are much more expensive than other variants. You can also opt for LED grow lights at this stage. The cheaper variants of LED are also alright at this stage. The most recommended and highly popular choice of grow lights at this stage is the HID Metal Halide. They have the capacity to offer great results for small as well as larger plants that fluorescent lights may not be able to give results for. Ceramic metal halide is also gaining popularity amongst seasoned growers.


At this stage many different types of grow lights offer good results and it is difficult to choose one over the other. The only disparity amongst them is the overall cost and efficiency they offer. Florescent grow lights are cheap, easy to source, and efficient for the veg growth at this stage. LED grow lights also give good results, including the cheaper variants, with lights that last a long time. HID has been, and continues to be, a popular choice of grow lights at this stage; including the cheaper variants.


-       Bloom Stage


This is the stage we all look forward to the most! All the attention and care finally shows results and your work starts blooming, quite literally! At this stage florescent grow lights are not largely recommended. You can use T5 at this stage but using the canopy method of growing and can expect good results from it. The T5 cannot penetrate too deep and thus cannot really help grow the lower portions and focuses just on the top. This could thus waste energy that can be saved by using the canopy method of growing.


High quality LED lights can also give great results in the bloom stage of growth. While some consider HPS to be the best grow light at this stage, LED is equally good. In fact, the overall cost of LED grow lights comes to be much cheaper because even though you may pay a higher price in the beginning the overall lower cost of energy, cooling and bulbs makes it a better option in the long run. HID lighting, especially the HPS is probably the best and most commonly used grow light for the bloom stage. It offers fantastic results and also has a low cost of setting up. The higher end variant gives exceptional results and using specialty bulbs can raise the great results even higher!


Different kinds of grow lights can be used at the bloom stage. It’s difficult to say which one is the best as each has its own distinguished advantages. But T5 goes to the bottom of the list of recommendations for sure! These can be used but the grower needs to take extra precaution while using these. High quality LED lights rank quite high in our recommendation list and also give good results for the money you spend for it. Traditional HPS and HID lighting are other good and recommended options at this stage.



Hope that makes it even more clear! Now that we know the different kinds of grow lights and also understand how each gives advantages at different stages of the plant growth, it now comes down to your personal space. Depending on your specific grow area, the size and whether it’s open or air cooled (AC) grow lights, you need to use the right wattage accordingly to maximize your growth results. Below is a basic guide to follow according to the footprint of your grow room:


2'x2' -- 250W AC or 150W Open

2'x'4' -- 400W AC or 250W Open 

3'x3' -- 400W AC or 250W Open

3'x5' -- 600W AC or 400W Open

4'x4' -- 600W AC or 400W Open

5'x5' -- 1000W AC or 600W Open

4'x8' -- 2x600W AC or 2x400W Open

8'x8' -- 4x600W AC or 4x400W Open

5'x10' -- 2x1000W AC or 2x600W Open

10'x10' -- 4x1000W AC or 4x600W Open

8'x16' -- 8x600W AC or 8x400W Open

10'x20' -- 8x1000W AC or 8x600W Open


These recommendations are based upon specific footprint of grow rooms. These are calculated on square footage with specific recommendation for Air Cooled (AC) and open reflector grow lights. Using higher watt grow lights may require additional cooling for the space due to the extra heat and is not recommended for a new grower. 


This basic and comprehensive guide to grow lights is especially designed to help newbies as well as be informative for seasoned growers. Every year, technology advances and newer and better products are added to the already long list of grow light options. It is extremely important to choose the right grow lights at the right stage of growth to maximize results and get a better produce. It may sound too technical, but once you get the hang of it, you’ll soon be making recommendations of your own. When starting anything out the first and most important step is planning. Once you have a basic plan sketched out, go into it deeper and make changes if necessary. You then start collecting your material and do the basic set up required. Again, stop and see if the setup complies with the plan. It’s always good to seek help and advice from someone who has experience. If not someone, we are always here to give you all the information you need about grow lights and getting the best growth results.


We hope this guide has been of help and you are now sure about the different types of grow lights and the ones to use at different stages of plant growth. We offer a large variety of grow lights that can help you get started and be of use all along the way of growing! There are many more lighting types, but we are sure this information is adequate and sufficient in itself to help you get started. Go through the rest of our eLearning guides and tips for more information. Happy Growing!