Mars Hydro 300w LED Grow Light Review

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by Morgan

Last update:

January 16, 2023

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During our Mars Hydro 300w LED grow light review we found, surprisingly, that for this particular Mars Hydro LED, although small, packed a mighty punch. For a small 300w LED it did a great job in our grow rooms and has made our list as one of the best small grow lights at an affordable price point. In other words, the Mars Hydro 300 watts actual wattage kept up nicely with other models of Mars Hydro lighting like the Mars II.

The Mars Hydro 300 watts version is perfect for beginners because it takes a lot of extra leg work away such as setting it up in grow tents are very easy, runs at cool temps due to smart choices of heat sinks and their customer service is outstanding.

If you are new to growing plants indoors, you have probably already figured out that you are going to need some good grow lights.

Being a new indoor gardener the real challenge is what led lighting is the best based on ease of use, cost, and other gardening factors.

We wanted to do a review based on the best grow lights for amateur indoor growers. Many brands of grow lights were thrown in the pot to be reviewed and as we shuffled through the different possibilities and finally landed on the Mars Hydro 300 watts LED grow light for many reasons.

Let’s get into the Mars Hydro 300w review in a second…


We chose the Mars Hydro 300W for a few good reasons that are geared to a new indoor grower.

  • An LED grow light for one costs less to run and operate than older bulbs that glow hot and have less spectrum than that of their Light Emitting Diode counterparts. Many advancements in LED chips make the Mars Hydro 300w an easy choice.
  • LED offers full-spectrum lighting, rather than swapping out different bulbs during different plant phases you only need one good LED grow light such as the Mars Hydro 300 watts.
  • The cost of purchasing extra fans is reduced because LED’s give off far less heat than a traditional HPS bulb.
  • LED grow lights last a long time. The typical LED lasts around 50,0000 hours. That is a ton of plants you can grow in that time frame.
  • Perfect for either hydroponic or soil-based growing in your grow tent.

Mars Hydro Mars 300W Review Specifications

mars hydro 300w review

The 300w LED by Mars Hydro is one of those models that are cheap in price but powerful in quality. A great combo that we saw in our Kind LED K3 review as well. We used a couple of different seedlings for our test review grow in order to give feedback, not only on the functionality of the light but also the final product and its yield. The strain of plants we used to grow was our indica hybrid bud, White Walker and a classic Maui Wowie.

Ordering 2 lights from Amazon the packages came and were discrete in the standard packaging, but there is an option on top of this to request discrete packaging should you live in a place that indoor growing is frowned upon. We started with our seedlings sitting beneath our easily hung Mars 300w LED.


The Mars Hydro 300w is easy to install in any grow tent. The packaging included a pair of steel hanging kits a power cord and of course the Mars Hydro LED grow light for our reviewing pleasure. There is no need for a fancy ballast as the hanging kit did the job and was easy to adjust as our plant canopies began to grow.

The 2 by 2 foot growing area was perfect for 1 plant at its recommended hanging height of 12″ to 30″ above the plant tops depending on the plant phase.

The full spectrum light produced from the LED is not bright to the naked eye but I always recommend using protective UV glasses when dealing with any LED as to not damage your eyes. A good choice (I own several pairs) is the Apollo Horticulture UV400’s. Affordable and provide decent protection.

Mars Hydro 300W Features Reviewed

  • 132 watts  — Power savings are great compared to HPS and HID bulbs
  • VDE and UL-certified safe wiring — easy to use
  • Low Heat Tubes – reduce fire dangers from lights being on extended periods
  • 85V-265V — can plug into European sockets as well as US
  • 50,000-100,000 hour 5w bulbs — long-lasting bulbs
  • Full-spectrum light with red, blue & white LED’s  — works well for all stages of plant cycles
  • 3-year warranty and 30-day satisfaction guaranteed — easily replaced or returned

Mars Hydro 300w Disadvantages

Single plant flowering is easy with this LED grow light. However, the strength of the light, being smaller seemed to lack the power it needs during the bloom cycle which gave us slightly lower yields. Not a terrible yield by any means but if you intend to grow more plants a larger wattage might be required. If you like Mars Hydro and need more power, we recommend the Mars Pro II 400w LED grow light.

For the 2020 version of the Mars Hydro 300w led grow light they added a single on/off switch for all stages of plant growth which is better than the past LED in which you had to unplug from the wall. The single switch for advanced growers is an issue but is a plus if you are new to indoor gardening with LED grow lights, which can take some guesswork out of the equation.

Mars 300 Watt Grow Light Review Verdict

We found during our Mars Hydro 300w review of this LED grow light that it has gone through a couple of revisions and their updated 2020 model is much sleeker, looks and feels more sturdy and includes 30% higher PAR levels compared to the older version of the Mars Hydro 300w LED grow light.

With the Mars Hydro grow light review, we also found that they increased the warranty from 1 to now 3 years, which says a lot about the quality increases with the latest version of this model.

From the affordable price to the ability to grow in tight places like a small closet or tent the Mars Hydro Mars 300 watt LED grow light is the perfect choice for those just starting out as new growers. With not many over-the-top features it keeps things simple and the price low. It is a great light that can teach you the fundamentals of growing and light supplementation.


1. Are Mars LED lights any good?

LED grow lights are a popular choice for many homeowners because they are energy-efficient and long-lasting. While there are many different brands of LED grow lights on the market, Mars LED grow lights are a reputable brand that is known for producing high-quality products. If you’re looking for an LED light that is sure to last, the Mars LED light is a great option.

2. How many plants can I grow under 300W LED?

You can grow a lot of plants under 300W LED, depending on the size and type of plants. For smaller plants, you could probably grow up to 10 plants. For larger plants, you may be able to grow 3-4 plants.

3. How far should a 300 watt LED light be from plants?

300 watt LED grow lights should be kept 18 to 24 inches away from plants.

4. How long do Mars Hydro LED lights last?

The lifespan of a Mars Hydro LED light is about 50,000 hours. This means that if you were to use your light for eight hours a day, it would last for about six and a half years.

5. How far should Mars Hydro light be from plants?

The distance between the light and the plants should be about 18-24 inches.

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About the author 


I discovered the benefits of Cannabis at a young age in 2002, with years of trial and error, my knowledge grew just like my plants. As my love for cannabis unfolded I began to teach and learn, trying to gain as much information and practical growing experience.

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