The 8 Best DIY COB Grow Light Kits Reviewed

Best DIY COB Grow Light Kits

Growing marijuana can be a challenging task, especially if you are doing it indoors and for the first time. There is so much that you need to know about it and the deeper you get into it the more complex it becomes. Lighting is one such complex topic as you’ve got to understand why your plants need light, how can they get light indoors, what kind of light they need, etc. Grow lights tend to play a major role when it comes to growing marijuana plants indoors. In this article, we shall be taking a detailed look at the 8 best DIY COB grow light kits and review them.

In case COB lights do not make much sense to you at this point, do not worry. We shall be going into the depth of what COB lights are and why should you be using them. We will also talk about the importance of DIY COB lights and then proceed to show you some of the best options that you have got when it comes to buying these kinds of lights which you can assemble on your own! 

Over the course of this article, we shall be talking about why lighting is important, what COB lights are, which are the best DIY COB grow light kits that you can buy off the web, and what are some factors that you need to keep in mind when you buy such lights or DIY kits. We shall also be answering some frequently asked questions about COB lighting before we conclude. This is a great guide for those growers who have already started off with indoor growing and are looking forward to experimenting with their lighting and learning new techniques about the art and science of lighting. 

Lighting for Marijuana Plants

Plants need light for a number of different things – primarily to produce food and for the process of photosynthesis to take place. When you grow your marijuana plant outdoors, it will make use of the natural light of the sun but when you are growing them indoors, you need grow lights that act as an artificial source of natural lighting. In this article, we shall specifically be discussing COB lights which are indoor lights. There are many different types of grow lights that you can use to grow weed –  these include High-Intensity Dicharghe grow lights, Fluorescent Grow Lights, and LED grow lights

Over the years people have begun to prefer using LED lights to grow their weed because of multiple reasons. First off, while their initial cost seems expensive compared to older forms of lighting, people have realized that they can make quite a big saving when it comes to the operational costs as these lights consume very little electricity. LED grow lights consume a fraction of power when compared to HID/Flourescent lights. Furthermore, they also produce the least amount of heat and do not damage the plants at all. Another major benefit is that even if a couple of chips stop functioning, the light will still function. Finally, the overall lifespan is significantly longer in comparison to older forms of lighting. LED lights can last about 50,000 to 100,000 hours without any problem! There are many different types of LED lights that exist. COB lights are also a kind of LED lights. Let us now take a closer and detailed look towards understanding what COB lights actually are. 

What are COB Lights?

When we say LED lights, most people usually think of panelled lights or quantum board lights. These are traditional LED lights which are also known as SMD lights – SMD stands for Surface Mounted Device where LED chips are fused on to printed circuit boards. These are the kind of lights that we see being used most popularly among growers. However, COB lights are also LED lights – but they are quite different in comparison to SMD lights.

COB stands for Chip On Board technology. While SMD lights have a maximum of three LEDs put together as one unit on a chip, COB lights allow you to put together far more number of diodes together. COB lights tend to have dozens – or in some cases even hundreds – of diodes fused on to the same circuit board. You generally get a much better lumen per watt ratio when you use COB LED lights, which means they are much brighter while consuming the same power as a traditional LED light. 

What is a DIY COB Grow Light Kit? 

A DIY COB grow light kit includes some elements which you can assemble on your own and set up your lighting system. To set these up you need COB lights, light holders, reflectors, and heat sinks as the primary equipment. In addition to that, you would require all the wiring and hardware that you need to assemble it all together. However, when you assemble all of it together, you would find it more satisfying that you are getting the best quality lighting for your plants!

8 Best DIY COB Grow Light Kits Reviewed

In the list below, we have a number of grow light kits going from small to very large in size which should help growers with different kinds of plants and for growers who grow a different number of plants. The wattage goes from 75 watts to 1500 watts, which will be suitable for growers of different ranges.

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1. Rapid LED 75W CREE CXB3590 COB LED Grow Light Fixture (3500K)

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To begin with, this is the most basic and beginner-friendly unit for growers who either want to experiment with DIY COB lights or are just starting out. If you are a small-scale grower who is growing very few plants this is perhaps the right choice for you. Here, you get an average coverage of about 22” x 22” – which is a little under 2ft by 2ft, ideal for growers who are growing like one or two plants. This is something that small scale growers can really benefit from. 

The PAR values that you get from this is also quite good for a small-scale setup. What makes this one of the best DIY COB grow light kits is that you get a PAR reading of 800 to 950 in the central areas. This DIY kit features the CREE CXB3590 Top Bin COB LED, along with the Mean Well HBG-100-48A driver as well as a high-quality and high performing Ledil ANGELINA XW Reflector. This COB light also comes with a rope ratchet setup which makes it easier for growers to hang it. All said and done this is a great option for beginners and novice growers. 

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2. Rapid LED 100W LED Grow Light Fixture, Samsung LED with 660nm Supplements

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Made out of aluminium and featuring LED chips made by Samsung (LM301B), this is among the best DIY COB grow light kits that you can buy in the markets right now! Offering 100W of lighting, this is somewhat of an improvement over the 75W grow light we saw above. This also covers a little larger area and allows the growers to grow properly in a 2×2 setup. Talking about other aspects of this grow light, the high quality Samsung chips are among its biggest attraction. Then there’s also the heat sink attached on the back side which will ensure that the heat does not gather inside the device and does not damage it. 

This COB light can be used during both, the vegetative growth phase as well as the blooming phase of the marijuana plant, which is quite a relief as you do not have to change the lighting setup every few months. The grow light comes with ropes and ratchets included in the package which will make it easy for the growers to hang their light. It also includes the HBG-100-48A driver from Mean Well which ensures great quality performance. All said and done this is a great DIY COB grow light kit which can be used to grow weed with ease!

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3. Rapid LED CXB3590 100W LED Grow Light Kit (DIY)

This is another 100W product but the coverage improves slightly here as there is space for more COB lights. This is among the best DIY COB grow light kits for growers as it comes with 2 CREE CXB3590 COB LED lights, along with 2 holders to fit them in. There are also 2 pin heat sinks of 140mm, which ensure that heat escapes the lights properly and they operate at cooler temperatures. The fixture included in this kit can be used for growing marijuana during both – the vegetative and the flowering phases. As mentioned earlier, this kit covers a larger area in comparison to what we have seen above. About 2.5-3 Square Feet can be covered using this kit.

This is also a dimmable setup, thanks to the potentiometer that is included with the DIY kit, which is great for growers as they can create a near-natural environment. You also get the Mean Well HLG-185H-C1400B driver in this grow light which is great and will help deliver a solid performance. In addition to all this, this COB light grow kit also comes with 2 reflectors which will help amplify the coverage of the light. Growers have found this kit to be quite useful for growing weed indoors.

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4. Rapid LED CXB3590 2′ X 2′ LED Grow Light Kit (DIY)

If you use the standard driver in this grow light kit, you will get a total wattage of about 150W using three 50W bulbs, which will be great for covering a flowering area of 2×2 square feet. Growers who grow their marijuana in a small-scale setup will really appreciate this light and will find it to be among the best DIY COB grow light kits. There are three COB lights here, each of which come with a 140mm pin heatsink for dissipating the accumulated heat. You also get a Meanwell HLG-185H-C1400B driver along with the kit.

3 extra-wide reflectors with hole are also provided along with this grow light kit, which will make sure that your light is intensified. Furthermore, the lighting on this kit is dimmable, allowing the growers to control the brightness of the LEDs using the potentiometer’s knob. You have the option of buying the dissembled or pre-assembled verison of the kit. You can even customize the spectrum and the LED driver that you want from the LED Grow Lights Depot website. One pro-tip on using this grow light is to provide some extra airflow to ensure that the running temperatures remain low as some growers have reported of heating related issues!

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5. Rapid LED CXB3590 2′ X 4′ LED Grow Light Kit (DIY)

Finally moving beyond the 2×2 area, this is a grow light for growers who have a slightly larger need – covering an area of 2 x 4 square feet, this grow light is ideal for those who use a basic 2×2 or 2×4 grow tent to grow weed indoors. This is among the most customizable and the best DIY COB grow light kits you can find on the web as you can buy it in spectrums of 2700K, 3000K, 3500K, 4000K, 5000K and 6500K depending upon your need. There are two options when it comes to the LED drivers too. The overall wattage of this DIY kit is 300W. 

This is a slightly larger setup as it features 5 COB lights, which come along with five holders and five heat sinks of 140mm. There are also 5 extra-wide reflectors which will be useful for the growers in amplifying the intensity of their light. On the other hand, when it comes to reducing and dimming the intensity of the light, you can dim the intensity of the light using the knobbed potentiometer that comes along with the kit. You get a 15 foot red and black wires for connectivity along with a main power cord for this grow light kit. The kit ships freely to the lower 48 states of the US and there’s no tax on it as well! 

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6. Rapid LED CXB3590 3′ X 3′ LED Grow Light Kit (DIY)

The CXB3590 comes out into the markets with an impressive 3×3 coverage which makes it a great choice for growers who have larger needs than 2×2 setups. When you take a look at it, this is a six-bulb setup where you get 3 on each side. This grow light makes use of high-quality Top Bin CREE CXB3590 LED lights, and features 6 bulbs, 6 holders, 6 reflectors and 6 heat sinks – each of which are critical towards making this one of the best DIY COB grow light kits that you can find in the markets. Various driver brackets and hanging kits also come with the package which will make it easy for you to set it up and hang it in your tent or your grow room.

This grow light kit is also equipped with a potentiometer which makes it easy for growers to dim the lighting as and when needed. Dimming the intensity gives the plants an “all natural” feel just like the sun would. Before the sun sets the intensity dimmens – similarly before the lights go completely out, they dim to provide the plants a real-life feel. Covering a 3×3 flowering space, this is a great fir for growers who have a setup that size!

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7. Rapid LED CXB3590 4′ X 4′ LED Grow Light Kit (DIY)

Moving forward from 2×2 and 3×3 grow light setups to one that covers a 4×4 area, this is a slightly larger variant which fits well for growers who are growing larger than small-scale setups but not something that is too large either. The CXB3590 4×4 features 12 COB lights arranged in rows of three. There are 12 lights, 12 holders and 12 reflectors, as well as 12 heat sinks to ensure that the heat doesn’t damage the product or the plants. Even with the heat sink, we recommend the use of external fans to keep temperatures cool because when 12 lights are operating some heat is bound to get generated. 

There are three HLG-185H-C1400B drivers that come along with this grow light. When you look at the wattage consumption, the light draws around 600W of power from the LEDs, and provides a PPFD reading of about 760 when you are not using reflectors. Reflectors can also be purchased separately for this grow light kit. What makes this among the best DIY COB grow light kits is that it comes with three potentiometer with knobs that allow you to dim each row based on your needs. Reflectors, substrates, canopy rails, driver brackets and hanging kits can be bought separately if needed. However, at this cost you’d wish it were included along with the kit.

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8. Rapid LED CXB3590 5′ X 5′ LED Grow Light Kit (DIY)

Our final product on the list – but the largest of the lot. This one can cover a flowering area of 5ft x 5ft, which is quite big. It can cover an even larger vegetative area. This is also a 12 light setup, but has an overall wattage of 1500W (while drawing about 900W from the power socket). You get 12 bulbs, holders, as well as 12 heat sinks featuring 140mm pins which will help keep the whole thing cool. Nonetheless, as suggested above, we would strongly recommend the use of external fans because so many COB lights put together are bound to generate quite a bit of heat. There are also 12 thermal pads included in this DIY COB grow light kit which make it easier for the heat to dissipate. You also get three potentiometers here for controlling the intensity of the light. All in all a great buy for those people who have a large setup and thereby have larger lighting needs.

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Buyer’s Guide to COB Grow Lights

How to decide which is the best COB grow light for your needs? There are a large number of options available in the markets right now but here’s a quick checklist of a few questions for you to make an easy decision. Answering these questions will give you a better perspective:

1. How many LEDs are in your COB light?

The more the number of LEDs in your COB light, the higher lumen per watt output you would get. In simpler terms, having a higher number of LEDs is always better. Number of LEDs in a COB light could range from about minimum of 9 running into hundreds! So always take a look at the number of diodes. Apart from the number of LEDs, the manufacturer also matters. Getting a grow light which has diodes manufactured by credible names such as Samsung is always better!

2. Check the coverage of the COB light

Coverage is perhaps the most important factor based on which you should buy any grow light! Measure your setup (or the size of your grow tent) and buy a COB light (or multiple such lights) which cover at least that much area. 

3. Can you use the light for all phases of the plant’s growth cycle?

This is another question that needs to be answered when buying the best DIY COB grow light kit for your plants. If you cannot use the light for both phases (vegetative and flowering), then you should perhaps look for other alternatives. Changing lights when your phase changes is a tedious task.

4. Make sure to check the Heat Sink

The heat sinks play a very important role in any COB light! These structures help the heat escape the light and make sure it does not damage the plants (or the light itself). Ensure that your COB lights have a high quality heat sink else you might have to use external fans to keep your lights cool.

5. Is the light dimmable?

Potentiometers in DIY kits help you control the dimmable nature of the lights. Having them is always an advantage.

6. How long are the cables and the power cord?

Make sure your cables are at least 10ft long to cover the entire bracket/kit.

Pros and Cons of Using COB Grow Lights

Here are some pros and cons about COB grow lights which every grower should know about:


  • High-intensity lighting solution compared to regular SMD LED lights
  • They improve the overall electric efficiency and consume lesser power than regular LED lights
  • Higher Lumen Per Watt output
  • More focused in distribution of light than standard LED lights


  • Tend to heat up and require the use of external fans to keep the systems cool

Frequently Asked Questions (FAQs) About COB Lights

Here are the answers to some of the most common and frequently asked questions about COB lights:

1. Why do my plants need light?

Plants need light for the process of photosynthesis to take place properly. Here, plants covert light into energy. Sunlight also helps break down sugars, as well as aides the process of formation of chlorophyll which keeps the plants green. 

2. Is it legal to grow weed using COB Lights?

As such COB lights are not illegal but growing weed in itself can be illegal depending on where you are living and what your local laws are. Make sure you are doing it only if it is legal as per your local legislation.

3. How much can DIY COB grow light kits cost me?

DIY COB kits range from $75 to $1000 depending on how big the coverage is and what kind of wattage you get in that grow light.

4. How to keep grow tent cool while using COB lights?

While most COB lights come with heat sinks of their own, we urge growers to use external fans (clip-on fans) to ensure that there’s a constant breeze inside the tent which ensures that hot air does not gather at one place.


In conclusion, we hope that this article has helped you gain a much better perspective and insights on COB lights and DIY COB grow lights than you had before heading in. We have tried and simplified each and every aspect of these lights, including an explainer on what DIY lights are and what all is a part of a DIY COB light kit. If there are still any questions that persist, do let us know over email or in the comments section and we shall get back to you as soon as we can! Till then..

..Happy Growing! 🙂


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