LED grow light manufacturers frequently bill their products as “full spectrum”, but what exactly are full spectrum grow lights? Does every full spectrum lamp give out the same light? And why should you care about whether a light is full spectrum or not?
In this post we’re going to answer all those questions for you and more. Plus, we’ll review four affordable models, so you can give full spectrum grow lights a try without spending a fortune.
Table of Contents
- 1 Using full spectrum lights for hydroponic and indoor growing
- 2 The Elements You need for Hydroponic Growth of Cannabis
- 3 How the Hydroponic Cannabis Process Works
- 4 What is a full spectrum LED grow light?
- 4.1 The absorption spectrum and the action spectrum
- 4.2 Do all full spectrum grow lights produce the same spectrum?
- 4.3 No perfect spectrum? So how to choose?
- 4.4 Beyond PAR and photosynthesis: Other important light wavelengths
- 4.5 Don’t forget about green light
- 4.6 No such thing as a white LED
- 4.7 Intensity also plays an important role
- 4.8 Full grow cycle too?
- 5 How to Choose the Appropriate Hydroponic LED lights for Growing Marijuana
- 6 4 of the Best Affordable Full Spectrum Grow Lights You Might Have Overlooked
- 7 Things to Keep In Mind When Selecting LED Grow Lights
- 8 What Makes LED Lighting the Better Choice for Indoor Growing
Using full spectrum lights for hydroponic and indoor growing
When you decide to start growing cannabis, you probably already have a basic understanding of the way the growing process works. However, there is still sometimes the debate about whether you should grow your plants indoors or outdoors.
Indoor growing has the advantage of complete control of your growing environment. And because you’re not tied to the seasons you can get through more grow cycles in a year. Many growers even claim that with a little practice you can get better yields, faster and with denser more potent and flavorful buds compared to outdoor growing.
If you are thinking of growing marijuana indoors, the best thing you can do is simply give it a go.
If you have been reading our site for any length of time, then you know that hydroponic grow lights are special indoor light lamps that simulate the sun’s rays. And in our opinion these types of led grow lights can help you grow marijuana faster—especially when you use indoor hydroponic growing methods.
However, figuring out which hydroponic LED lights work best for marijuana growth can be a bit confusing because there are many lighting options to choose from.
Read on and we’ll help you to choose the best full spectrum LED grow lights for your needs.
Wondering why we prefer LED to HID lights? Click the link for a full comparison.
The Elements You need for Hydroponic Growth of Cannabis
If you are decided on growing your own cannabis indoors in a hydroponic garden, you will need a few things to get you started. These are the basics for hydroponic growth.
- A nice sized growing space in your home, or even something like a grow tent
- Hydroponic grow lights that offer plants the same type of light as sunlight—or even better
- A growing medium such as peat or coconut moss that will support the root structure and base of the plant
- Nutrient solution
- pH tester to confirm the acidic levels of the growing medium
- Germinated seeds, or clones
Check out this article for a full explanation of exactly what hydroponic growing is, why you might prefer it to simply growing with soil, and the different types of system you can use.
How the Hydroponic Cannabis Process Works
Whatever the cannabis strain you choose to grow and whatever the hydroponic system you employ, the basic growing process is relatively similar.
You need to keep your grow area at about 80 to 85 degrees F and you must keep this temperature consistent throughout the growth process. If possible you want to use non-chlorinated water for watering your plant and keep it between 5.5 to 6.5 pH level.
You also need to get the lighting right and keep the overhead grow lamps at the proper height for even plant coverage. The right set of hydroponic grow lights can give you a nice even growth for several marijuana plants.
Let’s look at how to choose the right indoor hydroponic led lights to make your plants grow to their fullest potential.
What is a full spectrum LED grow light?
- Full spectrum means that a grow light contains every wavelength or color of light a plant needs to photosynthesize, usually focusing especially on the wavelengths the plant is able to most efficiently use and absorb. It covers the range of wavelengths between 390 to 700 nano-moles.
Photosynthesis is, broadly speaking, the process by which plants convert light into fuel; the photochemical reaction by which they feed themselves. Which is why good grow lights are so crucial to plant growth.
The absorption spectrum and the action spectrum
There are two light spectra you need to know about when growing cannabis indoors and when choosing your grow light:
- The absorption spectrum: These are the light wavelengths a plant can absorb and use for photosynthesis.
- The action spectrum: This is the spectrum of light that is most effective for photosynthesis, the light wavelengths that most actively drive photosynthesis.
The reason most grow lights give out a lot of blue and red light, for instance, is that the light wavelengths in those areas of the spectrum are not just readily absorbed by plants but are also those that they can most efficiently convert.
Good full spectrum grow lights cover all the wavelengths of light a plant needs, but also emit more of the wavelengths that your plants use best. In other words, they cover the absorption spectrum but in a ratio of wavelengths that fits the action spectrum.
This isn’t just good for your plants though.
It’s also good for your electricity bills, because no energy is being wasted producing light your plants don’t need.
Do all full spectrum grow lights produce the same spectrum?
No, is the short answer. Full spectrum is not a standardized term.
Spectrum for Viparspectra 1200W LED grow light.
However, the idea is always the same: to produce only the light wavelengths your plants most need and the specific quantity of each wavelength that your plants can best utilize.
Broadly speaking, a full spectrum light will cover the main bands of color in the PAR spectrum, i.e. the wavelengths between 390–700nm (see below for more about PAR). But exactly how much of each wavelength will differ from manufacturer to manufacturer, as well as the kinds of LEDs used and the way they’re set out on the light. Also, some manufacturers will add infrared and/or ultraviolet wavelengths too (again, see below).
Why the differences?
Because there is no “perfect” spectrum (there’s always a trade-off) and there’s more than one kind of LED technology. Different strains of cannabis have different light requirements, too. And some full spectrum LED grow lights are designed for a full grow cycle, while others are optimized more for veg or flowering.
No perfect spectrum? So how to choose?
Yep, no perfect spectrum. The problem lies in choosing the exact mix or ratio of each wavelength or band of wavelengths. Different ratios optimize or maximize different aspects of plant growth and of your end product.
Really, the best spectrum depends on what you want from your end product and how you’re going to use it. For example, are you going to be making oil, shatter, buds? Do you want high THC, CBD, flavor? Is your priority flower appearance or sheer weight and resin quantity? Edibles, vaping or smoking? And so on.
The BESTVA 2000W covers the full spectrum but optimizes more towards red wavelengths than some lights.
To optimize towards the end product you want, you can use a full spectrum light with an adjustable spectrum and gradually vary settings at different stages of the grow, to reflect how sunlight changes across days and seasons. Or just keep things simple using a fixed spectrum light for the whole grow and vary other factors—employing plant training methods, for instance, can have a big impact on yield and bud quality.
Many aspects of the final product are still very much strain specific, too. Not to mention the effects of other factors such as temperature, humidity, nutrients, etc. So we recommend that you research which strain you’d like to grow and its exact light (and environmental) requirements. Then choose a light that can best cover the optimal light conditions for your chosen strain.
Beyond PAR and photosynthesis: Other important light wavelengths
We’ve covered Photosynthetically Active Radiation (PAR) in more detail elsewhere on this site.
The short version is that PAR is the light wavelengths that plants can use.
However, either side of the PAR spectrum, there are additional wavelengths that plants don’t use for photosynthesis but which are nonetheless important to how they grow. Especially when you’re growing cannabis.
Ultraviolet (UV) light provokes various defence mechanisms in cannabis, which cause greater production of trichomes, terpenes and cannabinoids. Also, it helps light penetrate deeper below the canopy.
At the other end of the spectrum, infrared (IR) is supposed to speed up photosynthesis through the Emerson Effect. Which leads to optimal yield, budding and trichome production.
Don’t forget about green light
Plants don’t need green light…
Actually, they do. It’s a common misconception that all green light is reflected by plants.
Some green light is reflected, yes, and that’s why leaves and stems, etc. are green.
However, plants make plenty of use of green light (PDF). Green light quite literally reaches parts of a plant that other light does not. Plants can get by without green light, but they grow even better with it.
If full spectrum grow lights don’t include any green, then they just aren’t full spectrum!
No such thing as a white LED
LED technology can’t directly produce white light. There are no white diodes. Instead, there are two ways that LEDs produce light that appears white to the human eye.
- Method 1: Chips that are an equal combination of red, green and blue diodes.
- Method 2: Blue LEDs with a phosphor coating. (These are much more common.)
Both methods have their drawbacks in terms of efficiency. Moreover, whether light appears white is largely irrelevant to your plants.
However, the overall output of a full spectrum grow light is sometimes tailored to appear white to the human eye. Which is nice for you, the grower, because you can see your plants’ natural color and spot any discolorations more easily than when the light is tinted blue, red, purple, etc. But it’s the different wavelengths within this white-seeming light that are important to your plants.
Similarly, some manufacturers make the inclusion of some “white” LEDs a marketing feature. Why? Because in practice these so-called white LEDs are often the light’s main source of green and yellow wavelengths. Which is why they’re not an irrelevant feature when you’re looking for a full spectrum light.
That said, always check out the charts of the actual spectrum of light your plants will be getting. That’s what’s really important. Some people also argue that a smoother curve, rather than a spiky looking chart, is closer to natural sunlight and thus better for your plants. The advantage of the spikier spectrum is less electricity usage.
Intensity also plays an important role
Intensity or brightness isn’t about how bright the light appears, but rather the sheer quantity of photons that are falling on your plants and how far they can penetrate below the canopy.
The intensity of the light that a plant receives is conventionally marked by the wattage of the bulbs, and by how close you place the lamp to the plant. But when it comes to LEDs, wattage isn’t the main thing.
A light specified as 300W, for instance, could mean one of two things. Usually it means that the light is designed to replace a 300W HID light. However, sometimes it simply means that the light draws 300W at the wall. In the latter case, since LED technology is much more efficient at turning energy into light, the 300W LED light will actually be much brighter than a 300W HID light.
Plants differ not just in their need for certain colors but also in their need for light intensity. How much light they need also depends on their growth stage.
Unlike shade plants, marijuana plants require high levels of sunlight. So when grown indoors, they need high intensity hydroponic LED lights. You can judge their intensity by checking out the manufacturer’s PAR diagrams. Click here to find out more about PAR.
Full grow cycle too?
Lighting needs will change over the lifespan of the plant. For example, early stage germination of marijuana does not need light. However, once you have early stage sprouts, you’ll need to start using the hydroponic lamps for about 18 hours, whereas flowering stages only require 12 hours of lighting.
Many full spectrum grow lights can be used for a whole growth cycle. Indeed, many growers argue that using the same light(s) (often with some additional red lights added during flowering) optimizes growing times. Plants adapt themselves to the spectrum they’re getting. So when you suddenly switch to a different spectrum for flowering, it’s a shock to the plant. The plant has to adapt to the new spectrum, which slows growing time.
Once your plants hit the flowering stage, you can determine the sex of the plants and separate the males from the females. Remember, male buds are really only good for pollination.
How to Choose the Appropriate Hydroponic LED lights for Growing Marijuana
A good (though not perfect) rule of thumb is to stick to 32 Watt LED units and calculate one unit for each square foot of growing space. Especially on cannabis plants that are flowering. So if you have a growing space of about 16 square ft you would want to purchase a grow light of about 550 Watts. That is if we assume that your plans are all in a single area.
However, plants that are still in the vegetative state only need about half of this amount of light.
Also, always consider the specific light requirements of the strain you’re growing and choose a light that can give your plants the intensity required across the whole grow space.
Why do LED grow lights cover a smaller grow area during flowering?
When flowering, cannabis is usually grown on a cycle of 12 hours of light, 12 of darkness. Whereas during veg it’s receiving light for up to 18 hours a day. So, to compensate for fewer hours of “daytime” during flowering, the light is usually lowered closer to the plants to maximize the quantity of light falling on the plants. (You could also add another light, but for most people lowering the light is the best solution.)
So make sure to buy a light that can comfortably cover your grow area for flowering, not just at the veg stage.
4 of the Best Affordable Full Spectrum Grow Lights You Might Have Overlooked
Deciding on the type of hydroponic lights can be a challenge, as there are so many types and kinds to choose from. And so many different interpretations of the term full spectrum. That is why we’ve listed a few different hydroponic LED light options below to help you start your new project. If these lights aren’t the right size for your grow space, don’t worry, most of these models come in other sizes too.
While Viparspectra is already a well known name for cheap full spectrum LED grow lights, the other three models featured below might not yet have caught your attention…
VIPARSPECTRA 1200W Full Spectrum LED Grow Light for Indoor Plants Veg and Flower
While starting a project of growing marijuana indoors doesn’t seem like too complicated a project, if you’re going to create nice sized cannabis plants then you need a little beforehand preparation.
Okay, so you usually don’t need a lighting system with more than a thousand watts, which is what the Viparspectra has. But wait, this is an LED lamp that can help you grow any number of cannabis plants you need. It is a 1200W system. And while certainly not a cheap option, it is an effective one—and very competitively priced compared to similar units. It is a system that includes a full spectrum of light for your cannabis plants, which means it has appropriate lighting technology for all growth stages of the plant. All you need to do is adjust the amount of light exposure the plants get during the different growth stages. In the end, this LED light option offers a better solution, as there is no need to change out LED lamps when the plants mature.
The Viparspectra has an integrated cooling system which keeps the lamp cool at all times. There are six separate cooling fans built into the tray. This is a very impressive feature as most LED lamps come with less cooling power. For additional temperature control and LED chip longevity, we also see aluminum heat sinks, which further dissipate the heat produced by the lamp, affording a more durable LED lamp system. It is very versatile as it offers a much needed feature that other lamps just don’t have, and is one reason for the upper range in price.
Veg and Bloom switches
Unlike other systems, this LED light lamp offers a way of turning off certain spectrum colors at different growth stages, and it is this feature that allows you to better control the growth between vegetative and flowering stages. While the Viparspectra is rated at 1200W, that does not mean it draws this much energy from the electricity. It just means that this is the wattage of HID lamp it can replace. This system only consumes an average of about 524W of power but produces the same lighting for your plants as a 1200 watts HPS light. Warranty Coverage is also excellent here as this LED lighting system offers a three-year warranty.
BESTVA 2000W Double Chips LED Grow Light Full Spectrum
The Bestva system is a 2000 watt COB grow light. This high-tech innovation could make this one of the best LED light panels for growing cannabis. COB stands for Chip On Board, and it is the technology that keeps the LED panel cooler than in other lighting systems. The COB system on this lamp offers a large number of chips with well placed soldered points which give the light durability but less heat. The more solder points on a lamp the hotter it will run.
This offers a full-spectrum LED lamp safe for all plant stages. It covers an area of about 4×4 and a height of about 6.5 feet. You can’t beat this LED light system for durability either as it comes with a lifetime use of about 50,000 hours which is about 5 years of 24 hour use and substantial warranty of 3 years.
So if you have a mid-sized budget, and a smaller grow tent, the Bestva 2000 will do the trick. Again, although this system offers an output of 2,000 watts HID equvialent, it does not draw that much energy from the electricity. Amazingly, it only consumes about 390 watts.
Galaxyhydro 300w LED Grow Light Full Spectrum
Studies on hydro culture demonstrate that the use of more red and blue LED chips offers better growth of your marijuana plants indoors. The intensity and spectra is controllable on this lamp which means you can control the plants to create sturdier and greener cannabis. The LED Grow Plant Light is an option when a limited budget is a factor. Still, this grow light offers 300W (HID equivalent) with more red and blue chips than white.
Overall, this lamp is sturdy and well built (better than many others on the market.) It offers a hefty 5 pounds and measures about 12x8x2. There is only a 2 year warranty here, but for the price, it is a standout feature.
The Galaxyhydro also offers IR for photosynthesis and greener plants. The power consumption here is also as low as 140 watts which is a nice feature for beginner growers. While the lamp does not have COB technology there are integrated fans to help keep it cool when working. The manufacturer only offers a two year warranty on this lamp but it is still a good deal when we compare this to the build and the price.
Best World LED BWL
1000W 300W Double Chips Full Spectrum LED Grow Light
Editor’s Note (Feb 2018): Since we first wrote this article, it appears that this light has been re-listed as 300W (100 3W LEDs) and the warranty reduced to 1 year. We’re not sure whether the 1000W model was originally incorrectly rated or whether 3W chips are now being included on the same unit instead of 10W double chips.
While we originally included the BWL because the price was excellent for a 1000W light, the 300W version remains a very cheap full spectrum light, and there are certainly some happy customers out there. So if it’s the best you can afford and it suits your grow space, or if you just want to try indoor growing without a big outlay, it’s worth considering. However, we’d strongly recommend investing a little more, if you can.
Here are the main details:
Like the other panels we recommend, the BWL is full spectrum. However, it doesn’t include IR or UV wavelengths. Of its 100 3W leds 82 are red, 12 are blue and 6 white, so it’s probably more suited to flowering. The BWL 300W can cover a maximum grow space of… well, frankly, the manufacturer doesn’t say, but no more than 2′ x 2′ during flowering seems likely. Within the panel there are multiple heatsinks and fans to keep the lamp panel at an ideal temperature. The LEDs are rated at up to 50,000 hours lifespan and the warranty is one year. While the lack of detailed specs available makes us very wary, this is still a very affordable unit if you’re on a very tight budget.
For some other affordable 300W options we’re more enthusiastic about, check out our roundup of the Best Full Spectrum Grow LED Grow Lights for Under $100.
Things to Keep In Mind When Selecting LED Grow Lights
LED grow panels are a relatively new element in the cannabis growing world, but they are now extremely popular and when used they tend to offer better yields. With the average LED light you can expect to get about .05g per watt. Of course, this is not a hard set fact, as it also depends on the strain and how experienced you are in the field.
Modern LED panels have wide spectrums of light and make for healthier plants, and manufacturers have developed LED focal lenses that point as much light as possible at the plant and increase full spectrum light penetration.
LED grow lights for cannabis create higher yields, and offer cutting edge grow methods, however, you do need to make an initial investment, which as you know, will pay off over time.
What Makes LED Lighting the Better Choice for Indoor Growing
LEDs offer less energy consumption and give off less heat, so they won’t burn the plants when they are kept at appropriate heights. Unlike their similarly cool-running predecessor, the CFL light, LEDs are very intense so do need to be set at a higher level from the plants. But that makes these lamps a better option when you need more plant coverage. A general rule of thumb is to keep LED grow lights about 12 to 18 inches from the tops of the cannabis plants.