Mars Hydro 300W LED Grow Light (2024) – Reviews, Buyer’s Guide & FAQ’s

Last Updated on December, 2023 by Rob Wilson

Growing marijuana is an art as well as a science. While most people tend to see it as purely a technical thing where they need to provide a basic amount of light, heat, and water to their plant – it is actually much more than just that. It is also an art form – you need to know exactly which lights to use, which angle to use it at, and when to use what – and with an appropriate amount of ‘love’ that your plant must get. Growing a plant involves nurturing it with care and providing it the best possible equipment such as grow lights, tents, fans, etc. However, when it comes to the best LED Grow Light for growing marijuana, Mars Hydro 300W LED Grow Light comes out as one of the top names in the markets.

Grow lights are among the most important components for growing cannabis plants indoors. This is because they emulate the sun, which is the most important and essential natural resource needed to grow any plant as it provides the plants with light and heat. Hence, it is important for an indoor setup to have a great LED grow light which can provide the best possible substitute. Here, we have reviewed Mars Hydro 300W LED Grow Light for you – which we believe to be among the top names in the markets right now if you want a grow light for your indoor plants.

Let us now take a closer look at our review of this grow light – but before that, let us focus on why your plant needs grow lights

Understanding LED Grow Lights – Why Does Your Cannabis Plant Need a Grow Light?

In order for a plant to grow naturally, it needs air, water and sunlight which are the three basic elements available naturally. However, sometimes due to bad weather conditions, one (or more) of the three are not available and hence the growth of the plant falters. Light is the most important element as it is due to the light of the sun that the plants are able to grow upwards towards the direction of the sun and they can also let all the processes such as photosynthesis happen smoothly which provides ‘food’ and energy to the plants. Hence, light is the most critical element.

When you grow a plant indoors, you need to ensure that your cannabis plant gets the best grow lights because they provide the appropriate warmth and light which will allow the plant to grow as it would in nature. Moreover, it would take things one step further – if you’ve got your art and science in the right place and you have the right grow light such as Mars Hydro 300W LED Grow Light, you can actually tweak the settings to emulate a ‘best case’ scenario where your cannabis plant grows even better than it would under natural circumstances. 

Which is the Best LED Grow Light?

There is no clear cut answer to this question as there are a number of good LED grow lights in the markets, such as the Viparspectra 600W, etc. However, in our opinion, the Mars Hydro 300W LED Grow Light is among the best names that you can purchase today for your plant. In order for your plant to grow well, you need to ensure you get the best of products and with this Mars Hydro light you need not worry at all. While it wouldn’t be fair to call it ‘the best’ LED light in the markets, as that title just cannot be given to any single light because of everyone having different needs – this is unquestionably one of the best options that you have if you want to grow cannabis plants indoors.

Mars Hydro 300W LED Grow Light Features: What Makes it Special?

Now that we’ve said that this is indeed one of the best LED lights that you can get for growing a cannabis plant indoors, let us take a closer look at WHY we think so. First off, this is a full-spectrum grow light, which means it has multiple wavelengths and is quite similar to the natural light of the sun as it consists of lights of all colors. However, the focus here is on the red light as there are more red lights in this grow light than any other lights. Red light is beneficial for the growth of your cannabis plant as it ensures bigger buds and larger yields. 

This light comes with an upgraded power switch and a feature known as ‘daisy chaining’ where you can plug another grow light on to your grow light allowing you to create a chain of grow lights connected to each other with only one main light plugged to the main power source. It is also quite an energy efficient as compared to other similar grow lights. 


For a detailed understanding of why this is considered an ideal choice and among the best grow lights for marijuana and weed, here’s our complete review of the grow light:

Mars Hydro 300W LED Grow Light 2024: Reviews

Here’s everything that you need to know about this grow light before you purchase it! We have divided the features of this light into various sections where you can get a detailed idea about each of it. Here we go:

1. Design

First things first, the design of this grow light is the first thing that is going to catch your eye! Long-time growers would know that this grow light used to have an older, bulkier model. However, this new and improved Mars Hydro LED grow light offers the users with a redesigned version of its older self. The bulk has been removed from the sides and the broad white box that surrounded it has been replaced with a sleek black frame. In this new design, the heat sink has been removed! However, you don’t need to worry about that because it comes with a new fan and cooling slits which ensure that the heat will be dissipated. 

Apart from the exterior, the LED lights have also been tweaked here! SMD LED technology has been introduced in this new design, which the company claims to be 3 times brighter than regular LED lights. Mars Hydro 300W LED grow light also comes with additional red LEDs which ensure that the flowering cycle goes on smoothly. 

Talking about the design of this grow light, we also need to mention the ‘daisy chaining’ function, which basically allows you to create a series of plugged-in grow lights. You can plug one grow light on to another in this one with only one of them having been connected to the main power source. However, this is seen in most good LED grow lights and was also a part of the previous model.

2. Grow Light Spectrum

What is really cool about Mars Hydro 300W LED Grow Light is that it offers a full-spectrum, meaning it is good for all phases of the plant’s growth! It can be used well during the germination stage, the seedling stage, the vegetative stage all the way to the flowering stage! This light comes with a 12-band spectrum that ensures you get a high-quality output across all stages. You just need to ensure that your distance and your on-off timings are appropriate, thereby creating a best-case scenario for the indoor growth of your weed plant.

For those who want a detailed look at the spectrum, here are the numbers that this grow light offers: 400-410nm,440-450nm,450-460nm,630-635nm,650-660nm,730-740nmand 2700K-3000K

3. Light Coverage

Light coverage is an important factor when it comes to grow lights and buyers must know of what they are getting into. If you are growing larger quantity of plants you would require a larger coverage area and therefore need multiple of these grow lights. However, for those planning to grow on a smaller scale, one should be enough. The maximum light coverage that this grow light offers you is that of 2’ x 2’ (2 square feet). While this isn’t an exceptional quantity, it is indeed something that you must consider good enough considering the high-quality output that you are getting. 

4. PPFD Measurement

PPFD (Photosynthetic Photon Flux Density) measurements are also important as they help you measure the intensity of the light. While you know that you get a 2 square feet coverage area in this light, you need to know that the light is strong enough for it to properly penetrate through the leaves of your plant. When hanging from an 18-inch distance, the PPFD measurement of this light stands in at 190 umols at 1.5 square feet. When you keep a plant right under the light, it offers a PPFD reading of 450 umols. For most plants, this reading is perfect and ensures that you can grow them properly. 

5. Power Consumption

Power consumption is also an important metric that you should know if you are planning to make use of your own LED lights. While one thing is certain – power consumption of LED lights is always going to be lesser when compared to traditional form of lights such as filaments or gas, etc, making use of LED lights can also be confusing because while all LED lights are more energy efficient and cheaper compared to traditional lights, some LEDs are better than others! 

As mentioned earlier, this is a new and improved version of the Mars Hydro LED light. The older version of the light consumed 135 watts of power off your outlet, the newer version is more efficient and consumes even lesser electricity – just 110 watts of power! Power fluctuation is something that you need to be careful of with most lights, as it can go as high as 10% – but with Mars Hydro’s latest LED lights, you can rest assured that it won’t go beyond 5%. Basically, with an input of 110W, it offers you an output of 300W. While this offers 18% better power consumption, the real effect is visible when you use multiple lights you save a lot more!

6. Cooling

Everyone who has ever used grow lights to grow marijuana indoors knows exactly how important cooling is. Given that grow lights emit a lot of light and heat (emulating the sun), they tend to get heated up especially if you use them for longer periods of time. While this used to be more of a risk for traditional lights as compared to LED lights, this continues to be something that bothers many users. Overheating is not only bad for the plants as it might end up burning them, but it is also bad for the lights as it might end up damaging the circuits. 

However, this isn’t  a problem when it comes to the latest version of the Mars Hydro 300W LED Grow Light. The company came to realize that while it uses about 110 watts of power, the device doesn’t really heat up that much and the heat sink has been removed and replaced with a single fan on the back-side. The fan, too, isn’t that noisy and runs at around 49 dB on an average. There are cooling slits on the sides of this grow light which ensure that the grow light remains cool. 

7. Warranty

Last but certainly not the least important of it all – warranty is something that one must give a detailed look to. Hence we decided to give it a section of its own in our Mars Hydro 300W LED Grow Light review. This full-spectrum grow light comes with a 3-year warranty and they even have a service factory in California. In addition to that, the company is so confident of the product that it even offers a 30-day money back guarantee if you are unhappy with their grow lights. The customer service team is available online on Mars Hydro’s website which has an average turn-around-time of 8 hours.


Pros and Cons

Now that you’ve gone through the Mars Hydro 300W review in detail, here are some pros and cons that we have noticed that users of this grow light tend to face.

  • Great for beginners, easy to use
  • Consumes only 110W of electricity
  • Provides a uniform spectrum to all your plants under it
  • Easy to set up
  • Durable, low maintenance
  • Doesn’t heat much
  • Follows all the safety standards for cables and wires
  • 3-year warranty
  • 30-day return guarantee
  • Support team is very helpful


  • Lack of waterproofing
  • Not suitable for those who want a larger growing area (optimal coverage only of 2’x2’)


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Frequently Asked Questions (FAQs) Regarding Mars Hydro 300W LED Grow Light

  • What Do You Get In the Box?

When you purchase Mars Hydro 300W LED Grow Light, you get the following items out of the box: 1 ECO 300W LED Grow Light – the actual light that you have ordered, along with one power cord which is 6.67ft (200cm) in length. In addition to these essentials, you also get 1 hanging kit which allows you to hang this light at an appropriate distance from your plants. This is adjustable and you can move your lights up and down based on the stage of growth your plant is at. 

While these three things are the bare minimum of what you’d expect, this grow light also comes with some other items which you might actually find pretty useful. First off, there’s a thermometer packed in with the light, which ensures that you always know what temperature of heat the light is emitting on to your marijuana/cannabis plants. It also comes with a timer which allows you to automate the on-off cycles even when you’re not around. Finally, there’s an instruction manual which comes bundled with the product which tells you exactly how to use it. 

  • What is the Cost of Mars Hydro 300W LED Grow Light?

Under normal circumstances, the Mars Hydro 300W LED Grow Light costs $89.99 – however, Amazon runs offers and discounts from time to time where you can insert a coupon on the page where you buy the light and voila! You get a discount on it. In any case, even without the discounts and coupon codes, this is indeed a very good price to pay for a great LED grow light. Amazon also offers free shipping on this grow light on most places. You can also get other Amazon features such as one-day delivery on this if your region is eligible for that. Basically, at almost $90, this is truly the perfect bang for your buck. 

  • How to Use Mars Hydro 300W LED Grow Light to Get The Best Output?

Depending on which stage of growth you are, you need to make use of this grow light in a different manner. At the germination stage, when the plant is yet to sprout out from the seed, you need to hang the grow light the farthest from it. An ideal distance of 24 to 30 inches is preferred during this phase. As your plant starts growing and enters the seedling phase, you need to take the grow light a little closer to it – at about 24 inches. Once it progresses from being a seedling to a vegetative phase, you can move it even closer – at about 18 to 24 inches, so that it offers even more intense light and warmth. Finally, at the flowering stage, you can move it to (or let it be at) 18 inches. Ensuring that you move the lights closer to the plants from time to time ensures that your plants grow in a really good manner. This is something that you need to take good care of. 



  • Rob Wilson

    Rob Wilson is a maverick horticulturist and alchemist of the herbal world. With an uncanny green thumb and a passion for unlocking the secrets of cannabis cultivation and processing, he blends science and artistry to orchestrate nature's most intricate symphony. Rob's journey is an odyssey of coaxing delicate trichomes and potent terpenes into harmonious existence. When not lost in his garden, he's a devoted educator, guiding fellow enthusiasts through the verdant realms of cannabis cultivation. Wilson Rob