Overheating, burning leaves, melting plastic sheets – these are just some of the concerns when discussing what grow lights are best for growing weed indoors.
Though there are many solutions that provide a full spectrum light, not all light sources are created equally, not even those from the same category.
Different manufacturers have different designs and views on how to approach the concept of grow lights. To make it easier for you to understand the differences, here are our top picks and our complete buyer’s guide for weed-growing hobbyists looking at best lights for growing weed - complete reviews and comparisons are surveyed.
Best Lights for Growing Weed Reviews
1. MiracleLED Commercial Hydroponic Ultra Grow Lite
These LED bulbs are recommended for growing both plants and vegetables in grow tents or hydroponic systems.
The bulbs are 12W each. If you’re looking for an energy-efficient solution, MiracleLED might be on to something. The bulbs also come in a variety of colors.
Another good reason to consider these bulbs as your go-to indoor grow lights is the fact that they don’t emit a lot of heat. However, that doesn’t mean that a proper distance from the plants shouldn’t be considered.
What's to like about the MiracleLED Commercial Hydroponic Ultra Grow Lite
LED lights cover a wide spectrum of wavelengths that covers both the blue end and the red end. These are essential to weed plants when they’re young and respectably flourishing.
What's not to like about the MiracleLED Commercial Hydroponic Ultra Grow Lite
If you put the lights too close to the plants, you can still burn the leaves and the flowers once they reach maturity. Even if multiple bulbs don’t increase the temperature in your grow tent by much.
2. Relassy LED Grow Light
This is a rather sophisticated LED grow lamp you can get for your home and use over individual grow containers such as those found in modular DWC hydroponic systems.
The lamp has a 20W power draw – the light is equivalent to that of a 45W incandescent bulb. It also comes with two light sources, each of which is equipped with 88 LED lights. The lights cover a full spectrum which means you get plenty of blue and red light for your weed pots.
Extra heating is not an issue. The lamp has a solid aluminum heat sink. It also has a flexible gooseneck of stainless steel. This allows you to adjust the height and intensity of the light. The table clamp allows you to secure the lamp in various positions and locations in your home.
The lamp is of course multi-purpose. It can also double as a desk lamp which you might find very useful at some point. This is because of its limitation as a complete solution for a hydroponics system or a small grow tent.
What's to like about the Relassy LED Grow Light
Given the full spectrum coverage, using the Relassy dual-head grow lamp for 10 hours a day should be enough to spark a faster grow rate than growing your weed outside in the garden.
What's not to like about the Relassy LED Grow Light
The longevity of this dual-head lamp is somewhat concerning. On the one hand, the LEDs are rated at 50,000 hours lifetime and yet the light decay limit is rated at 18 months.
3. Sansi 15W LED Grow Light
These LED lights come in two colors – yellow and rose. This means that the wavelength spectrum coverage is not as impressive as you might see from other LED bulbs.
The rose Sansi bulbs should provide very good lighting for plants that have reached maturity. All bulbs fit standard E26 sockets, so you don’t have to buy a complex lighting and mounting system for your indoor garden or hydroponics setup.
These LEDs come with a ceramic heat sink. This allows for highly efficient heat dissipation, which is required of LED bulbs which generate a lot of heat and zero irradiation (nearly the opposite of incandescent bulbs).
Given the power and light distribution, the bulbs should cover an area of about 2.8 square feet. That’s while being mounted at a height of between 12 and 20 inches above the plants.
What's to like about the Sansi 15W LED Grow Light
The 5-year warranty is just hands-down amazing. LED lights are also subject to dimming over time, but that’s something these Sansi lights are not particularly prone to do.
What's not to like about the Sansi 15W LED Grow Light
Although advertised as having full spectrum coverage, the color filters applied to the bulbs seem to favor the medium to high end of the spectrum. This means that they’re not as efficient for weed in its infancy stages.
4. Hydrofarm Agrobrite FLT24
This is a T5 fluorescent grow light panel (also available with T8). It is somewhat powerful and expensive, but it covers a large area and it’s one of the most energy efficient choices for growing weed indoors.
Hydrofarm offers its FLT24 panel in three patterns – 2 tubes, 4 tubes, and 8 tubes. Depending on how large an area you have to cover, you can take your pick. The T8 is available in 4-tube panels.
The T5 tubes are rated at 6400K each and the combined light emission is up to 16000 lumens for the 8-tube panel. This doesn’t make for the most powerful system, but the coverage area is humongous, best if you’re growing in a whole room.
What’s also interesting is that you can hang these profiles overhead, vertically, and horizontally. This can make all the difference if you use a modular hydroponics system layered on various shelves.
What's to like about the Hydrofarm Agrobrite FLT24
The main highlight of this system and any other fluorescent grow light system is the energy efficiency and wide coverage.
What's not to like about the Hydrofarm Agrobrite FLT24
Hydrofarm doesn’t sell its fluorescent grow light systems for cheap. Yes, they’re energy-efficient but not everyone can afford the initial investment, but it’d make sense for those with larger tents or grow rooms.
5. Sun System HPS Grow Lights
Just in case you’re bored with LEDs, here’s a very effective 150W HPS (high pressure sodium) grow light for your small weed crops.
This lighting system comes complete with a heat sink and mounting box. It has a lightweight design which means it can easily be used in a small grow tent.
It covers a rather large spectrum of light. This gives your weed enough blue and red light to cover the entire growth process.
What's to like about the Sun System HPS Grow Lights
HPS lights tend to give out a lot of heat. But due to the design of this mounting system, enough heat is absorbed close to the source instead of being released into your ecosystem. This also allows the inline fan to dispose of most of the heat before it interferes with the plants.
What's not to like about the Sun System HPS Grow Lights
Although powerful, this HPS grow lighting system is also power hungry. It’s probably best suited for rooms with very poor lighting to begin with.
Types of Grow Lights
There are two main types of fluorescent grow lights that you can use to grow weed. There are T5 grow lights which come in panels and can be attached a couple of inches above the plants without burning them.
There are also CFL grow lights which are found as twisted bulbs. They’re available at hardware stores and they fit in the smallest of grow tents. Fluorescent lights put out a lot of light, which is why they’re used in factories and warehouses.
Light emitting diodes – LEDs. These are rapidly becoming the industry standard when it comes to growing weed. One of the reasons is the large wavelength spectrum that they cover from 250nm to over 1000nm.
Many plants require wavelengths from both the blue spectrum and red spectrum. This means that they need light sources capable of delivering wavelengths of around 450nm and 730nm. But this gets too tricky for most artificial light sources to deliver.
Why? – Plants need different wavelengths at different stages in their development. This is what makes LEDs so valuable. Another reason is the outstanding lifespan.
They also come with a downside. The cost is quite high. Depending on the brand and setup, you could end up paying up to 10 times more on an LED setup to get the same amount of light as a basic HPS system.
Metal Halide (MH)
MH lights are also referred to as gas lights or discharge lights, or a subcategory HIDs (High-Intensity discharge lights). The way these lights work is by passing electrical currents through a tube that’s filled with gas. These lights have the highest level of intensity and are therefore the brightest grow lights.
MH bulbs offer enough blue light, better than HPS and other HID sources. However, they’re not too energy efficient. Although good enough by some standards, MH bulbs aren’t used in small setups such as small home tents.
High-Pressure Sodium (HPS)
HPS lights are probably still the most common and popular choice as far as grow lights go. The light beam of an HPS light source tends to cover the yellow to red range of the spectrum. This is between 565 and 700 nanometers.
The lifespan of HPS lights is very good. Most of them are rated up to 10,000 hours or more. However, it is suggested that they are changed a lot sooner than that to maintain a high quality light. Although the bulbs may not go dull, the light becomes less intense over time.
Another problem with HPS bulbs is the heat. The bulbs give out more heat as they get older which could increase the temperature in your grow tent or room too much.
Although widely used, HPS lights are almost never used as the primary grow light source. They are often used as secondary light sources. Because of the color of the light, an HPS light source can’t give plants anything from the blue range of the spectrum.
Sulfur Plasma Grow Lights
Sulfur plasma lamps as a light source are even newer than LEDs. They’re not cheap and not that common. However, because they’re supposed to be as close as it gets to sunlight’s wavelengths and frequencies, they are believed to be a potentially revolutionary solution. They’re also the only grow lights that use microwaves to emit light.
Grow lights only do so much. Your weed crops wouldn’t get almost anything out of an overhanging lamp if the walls and ceiling of the tent or room weren’t covered with reflective material. White plastic and silver mylar are the two most popular at the moment amongst hobbyists and professional growers
Mylar is the better of the two. It has a very high reflective efficiency of around 90%. The material is a bit expensive, at least in comparison with white plastic, but it is also less malleable which makes it less susceptible to wrinkles, bubbles, and waving, all of which could create damaging hot spots.
White plastic is the cheapest reflective surface you can get for a grow tent or the walls of your grow room. It has a decent reflective efficiency of around 80%. However, it is a lot harder to maintain a smooth surface and prevent hot spots.
There’s also a concern regarding melting points. When used in combination with powerful light sources, the plastic could melt if the light is not distributed evenly throughout the tent. The material may also cause some excess humidity which is not a good thing.
How many LEDs should you use for your weed crop? – This depends on the size of your grow tent or grow room. To find a rough estimate, you should first do the math on how much sq. ft per plant you’re using.
Then you can calculate how many LEDs you need by multiplying the wattage of the LED bulb with the sq. ft of your farm. But, keep in mind that LED lights are not all the same. Comparing different LED setups is not like comparing HID lights.
This formula for a rough estimate might force you into making too big of an investment. When possible, check the manufacturer’s specifications or recommendations on square footage coverage.
LED grow lights win the lifespan race. With around 50,000 hours of runtime, they’re a solid long-term investment. However, because of their high initial cost, they might not be as efficient as HPS lights just yet.
HPS lights also have a decent lifespan. 10,000 hours looks great on paper. However, due to the fact that they start losing their efficiency quite quickly, after about 5000 hours, you may need to replace the bulbs sooner than that.
At the end of the day, it depends on what you’re looking to get from your weed crop and how much you care about your electric bill. Fluorescent lights may also work up to 10,000 hours at a much lower cost but with a considerably lower yield.
No matter which you go for, keep in mind one thing. LED technology has not been perfected yet. It gets considerably more advanced every couple of years. There are already LED lights on the market that can last up to 100,000 hours.
Power & Energy Efficiency
Whether you’re growing weed for profit or personal use, energy efficiency is super important. Weed needs plenty of light, therefore you’ll be running those grow lights a lot. If you’re looking to save a few bucks on electricity, fluorescent lights are a good place to start.
But these lights aren’t as powerful. Compared to HIDs for example, fluorescent lights can produce as little as a quarter of the yield per watt. However, just because HIDs are more powerful doesn’t mean they’re always the optimal choice.
All that extra power produces a lot of heat that needs to be managed. Not only that, but they also draw a lot more energy which means your electricity bill will skyrocket in comparison.
LED lights are not always as energy efficient as you may think. There’s no real standard yet so different models of lamps and different wattages will have different results. Some LED lights can still produce enough heat that you need to provide extra cooling. This adds to the electric bill.
And, in terms of raw power consumption, again LED lights differ greatly from one manufacturer to another and from one lamp design to another. Some of these setups you find on the market don’t give you the same value per watt as HPS grow lights.
Combinations of LED and HPS lights are still common as the two complement each other, especially when used in medium-sized grow tents. But as far as raw cost efficiency is concerned, nothing beats a fluorescent grow light setup. Fluorescent lights also run the coolest.
Lights for Growing Weed FAQ
How to use grow lights?
Grow lights should be mounted on the ceiling of the grow tent or grow room. That way the light can get total coverage over the entire crop. It is important that you use an adjustable mounting system. Weed needs a different light intensity and wavelength depending on its maturity.
For the most part, the lights also play a major role in setting the temperature in a grow tent. Because of this, you may want to get softer or more powerful lights to tend to your plants. If you have poor insulation in the room and your house is not particularly warm, you could compensate by using stronger lights in the grow tent.
On the other hand, if your inline fan can’t handle the heat or if you’re afraid of actually burning the plants, then softer lights like fluorescent bulbs or panels may be a solid choice.
What is a grow light?
A grow light – also known as a plant light – is what we call artificial light sources used to stimulate plant growth. They are usually electric light sources that emit sufficient light to support photosynthesis.
How do grow lights work?
Grow lights give the plants what they need to achieve photosynthesis. Some compensate for the lack of sunlight by emitting similar wavelengths. Others are designed to provide a specific spectrum that’s better suited for specific plants – in the case of weed, blue spectrum and far-red spectrum.
Because of this, some artificial light sources also produce a lot more heat than others, so they require a much more carefully thought-out setup.
What kind of lights for growing weed?
Different-sized tents may need cooler lights such as fluorescents. Others want the maximum gram yield per watt and don’t care about electricity costs. Then HPS and LED lights become the obvious choices.
Weed grows with pretty much any type of grow light. But your crops will yield more with some lights as opposed to others. The choice should come down to personal preference or specific tent requirements.
How far should LED grow lights be from plants?
If there’s one mistake that most hobbyist weed growers make is thinking that cooling the grow tent is enough to make it ok to hang the LED light closer to the plants. LED light is very intense and despite the beefy heat sink, it can often burn plants when kept too close.
Unfortunately, LEDs are still constantly retouched, reimagined, and improved. This creates a bit of a problem. There’s no set standard yet as to how high or low to hang your LED lights in your grow tent or grow room.
Different manufacturers might have different specifications listed on their LED setups, so it’s best to consult the manual if you want to get a sense of proportion. Some rough approximations would be about 30” or higher for high wattage setup (300W+). And anywhere between 18 to 20 inches for a 5W bulb.
Still searching for the best lights for growing weed? – You need to condider all the factors for your set-up before making your choice. The grow lights can make or break your indoor crops and harvesting plans.
There is a wide variety of grow lights on the market, but even with the increased popularity and availability of LED solutions, you can’t always pick the same lighting system to tend to your crops.
Whether money, space, or results are of prime concern, all the lights on the market today are relevant in their own way.