How To Find the Right Indoor Light on Amazon, Ebay, and Walmart
It's a real jungle out there. There are just pages and pages with LED grow lights of various shapes, forms, sizes, and prices. Some brands make ridiculous and confusing claims about their lights, other brands withhold crucial information which makes it difficult to compare one light to the other. We'll teach you what to look for, what to look out for, and how to compare one light to the next.
We'll also explain the basics to understanding grow lights and the most common terms used when measuring and comparing the lights' specifications and performances.
Our focus will be on lights in the lower end of the LED grow light price range, around $100-200.
Look up the brand; website, socials, responsiveness
If you're going to spend a significant amount of money on a grow light, you want to be sure you're buying it from a good and reliable source. When you find an interesting light on Amazon, for instance, look up the brand elsewhere. Do they have a website? Do they have social media channels? Can you reach them on Facebook or by email? A complaint we often see in the business is that some brands don't reply to customer questions or emails. To us, this is ridiculous as we feel that a fairly expensive product should also come with good after purchase care.
One more thing. A high review count on Amazon doesn’t always equal a good product. As several news sites report, there are plenty of fake or bought reviews floating around on Amazon. Apply critical thinking!
Location-based? China, US, EU?
It's no secret that the American and European online marketplaces are getting flooded with brands from all over the world, primarily from China. While "Made in China" doesn't reflect the products' quality (I mean, even our expensive phones, laptops and TVs are all made in China), it speaks a lot about the seller and the way they do business. It's usually easy to get an idea of the seller's location and origin simply by looking at a product's description: product/listing title, images, and the describing text. Phrasing, sentences, and grammar will be a bit off and just by reading a couple of lines the signs are there; subtle but visible.
If a product looks generic and the same (or very similar) design is used widely across different brands it's also a common sign of non-US/EU brand. While a sellers' base isn't necessarily a deal breaker, it leads to my next point…
Generic lamps, generic lamps everywhere (brand names crossed out).
... do the sellers know what they are talking about? Do they grow themselves?
Manufacturing a light is not that difficult. However, putting together a light that is good and efficient, is harder. A grow light should be practically tested and used to determine how well it works. In many parts of the world, China for instance, growing cannabis is a big no-no. Some plants (tomatoes) have very similar characteristics to marijuana and could to some extent be used as substitute test plants, but even this is done at a very small scale.
To conclude this point: find a brand that knows what they are doing, knows how to grow, and knows the product they are selling. There's quite a lot to it to make a good light. If a brand can't present their product well it's a sign that they don't fully understand it or its use.
How reliable is the lamp's information and specs?
It's easy enough to write "1000W Grow Light", "Super High PPFD/PAR" or similar claims online. Consumers rarely try or are able to verify this. Expensive testing equipment such as Apogee quantum meters are required to accurately measure light intensity (PPFD) which aren't an economically viable option for small scale grows or hobby growers.
Our suggestion is to cross reference the specs and information on as many different sites and places as possible. Ideally, you'd want to see videos of live recordings and testing, or testing by independent users that are knowledgeable in the field.
It's also important to know which values to look for. A typical misleading trick is to boast with watt (W) claims. 1000W, 1500W, or greater values. For inexpensive grow lights (<$500), this 1000W> value will never reflect the consumed watts (draw power) but rather the total wattage of the chips/diodes used in the light. Diodes come in various sizes; 1W, 1.5W, 3W, 5W, 10W, 15W, etc, and some brands like to count the total number of diodes and multiply it with the diode wattage. Eg. 100 diodes at 15W would be presented as a “1500W light”.
The truth is that the smaller the diode, the more efficient it is. This is important to keep in mind and this claim can also be verified in plenty of other places online.
The 1000W+ claims some brands make either refer to which HID/HPS lamps their LED light could replace, which is highly inaccurate as there really is no reliable way of comparing HID/HPS to LEDs out there other than light coverage and intensity (more on this later).
Or, they refer to the total wattage of the fitted diodes, ex 100 diodes at 10W each = 1000W. The problem with this is that a high diode wattage doesn’t speak about the lamp’s performance. As mentioned previously, the higher the wattage the less efficient diode but also that large diodes product larger amount of heat. This means they need to be run at a lower maximum capacity.
Theoretically, 10W or 15W diode could produce more light than a 3W but looking at the draw power for these "1000W" and "1500W" lights we see that they consume about 150-200W. This means they are running at around 15% of max capacity (150W draw power/1000W total LED wattage = 0.15 = 15%). Smaller diodes, with good heat disposition, can run at 50-60% capacity.
10W diode at 18% capacity will actually draw 1.8W (10W*0.18 = 1.8W)
3W diode at 60% capacity will also draw 1.8W (3W*0.6 = 1.8W), meaning the total light output of these two diodes will be roughly the same. But it’s obviously much less sexy to write “300W LED grow light” than “1000W LED grow light” so some brands opt for large diodes. See what I mean by misleading information?
Here’s an example of a popular light that makes false claims and also boasts with misleading information. 185W consumed/1000W diode wattage = 0.185 = 18.5% of max capacity in average per diode. 18.5W output per diode, similar to a 3W diode but 3W generate less heat.
Less heat (lower operating temperature) equals longer lifespan.
Understand your needs
This is pretty straight forward. How much money do you want to spend, or can afford to spend on a light? You typically need to spend about $100 for a grow light that produces enough light for 1-2 plants. Around $150-200 for a light that covers 2-4 plants.
If growing a high-value crop you quickly recoup the investment after a harvest but you may still want to start out with a reasonable budget. If you're growing primarily as a hobby, the price point of your light may be even more important.
A rule of thumb is: higher grow light price = more light = better coverage = more plants = bigger harvest. Pretty logical. A small and cheap (<$50) grow light simply can't be fitted with enough light emitting diodes to make any significant light impact on large plants such as cannabis. They may work well for smaller plants as herbs, spices, and some veggies, but large plants will need a lot of light to bear fruit/buds. More on this later.
Here’s a picture of a marijuana plant (autoflower) that has already transitioned into its flowering stage but due to the lack of light it received, it’s tiny and doesn’t look very healthy.
Grow area (light footprint)
Ask yourself how many plants you intend to grow? How big are they expected to grow? How large area does your light need to cover?
As light (and water and nutrients) is your plants' "food", if they receive less than required, the plants will not grow to their full potential, as per the picture above.
Not every square inch (or square centimeter, for non-US growers) of the plant needs maximum possible light coverage for the plant to thrive, but the majority (the more the better) of the plant should be well illuminated.
Indicas grow smaller than sativas in general but it also comes down to how you manage the plant throughout its grow cycles. You can train the plant to grow a certain way and have a certain size or area.
Beginners that are still learning plant management will likely have smaller plants, around 1-2 square foot (~0.1-0.2 square meters) per plant, than experienced growers.
Find a grow light or a number of grow lights that cover the area of your grow. Sometimes it makes more sense to buy two (cheap) lights rather than one expensive.
The area a light illuminates should be specified by the grow light manufacturer. If this info is not available, it suggests the seller is either withholding information or doesn’t really know how to best use the light.
Here’s our LEDTonic Z5’s light footprint. The area marked with green is our recommended grow area. The tests were made in a 3x3’ tent. If using a 2x2’ (4 square feet area) tent, which we recommended, light will reflect off the walls and better illuminate the outer edges of the 2x2’ area, increasing the PPFD. More on PPFD below.
Light output and intensity (PPFD/PAR)
Your plants need a certain amount of light to grow. To keep this guide short and in point, your weed plants will need around 300 PPFD (sometimes also referred to as PAR) when they are small and in their vegetative stage, then about the double (600 PPFD) during flowering. With added CO2 and the right ratio of nutrients, temperature, and humidity, cannabis plants can take even a bit higher PPFD levels but 600 is still a good general rule of thumb.
Smaller plants like herbs (basil, rosemary, and microgreens) require about 150-200 PPFD while veggies (cucumbers, peppers, tomatoes) can take anywhere from 200-600 PPFD.
PPFD basically means photon density; how much light hits a certain area every second.
High PPFD means high light intensity. To put it plainly; see this as sunbathing at the beach. If you'd go to the beach in north Canada you'd get less tan (low PPFD) than going to the beach in southern Florida (high PPFD). To get tan you need plenty of (sun) light. Same thing goes for plants but the light is measured in PPFD.
Light color spectrum
Plants need a full spectrum of both blue, green, and red light, similar to the sun.
Light is fundamentally photons; light particles with a certain wavelength (color). Light color is measured in wavelengths, nanometer (nm). Blue light has the shortest wavelength of around 400-475 nm, then green 475-550 nm, yellow/orange 550-625 nm and red 625-700 nm.
LEDTonic Z5's light spectrum
Various research says an ideal color spectrum for plants consist of 15-20% blue light, 15-25% green light, and about 60% red. This balance is optimal plant growth, health, and photosynthesis. The natural sun color spectrum has more green and yellow, and less blue and red but plants actually thrive when boosting blue and red a bit.
Practically every brand and every grow light out there has a different spectrum (different ratios between blue, green, and red). Most of them claim they have the "perfect full spectrum light" when the reality is different. Some brands even make this claim when they barely have any green light at all coming out of their grow light.
Here’s a picture from an Amazon listing that advertises the light as “full spectrum” but its spectrum chart clearly shows a spectrum with almost exclusively blue and red. Brand name crossed out.
In short; look for a color spectrum that has a decent amount of blue and green but a lot of red as it's the red light that the plant craves the most. Looking at large scale cannabis grow operations or industrial grows, you'll see that they never use BLURPLE (blue-red-purple) colored lights.
Lamp efficiency and watts (efficacy in umol/J or PPF/W or PPE)
You want a grow light that is efficient; high efficacy measured in umol/J (or PPF/W or PPE, same thing, different names). An efficient light will be able to put out (emit) more photons (light) per consumed electricity (watts, W). Typically grow lights in the cheaper price range ($100-200) will consume anywhere from 50W to 150W. This should be specified by the manufacturer.
More consumed (drawn) watts somewhat correlates to more light output, but there are TWO additional important factors to add into the mix: (1) efficacy and (2) spectrum.
1. Efficacy means the grow light's efficiency in turning electricity into light. High efficacy, measured in umol/J or PPF/W means the lamp is better at converting electricity to light.
Grow light A consumes 100W and has a 1.0 umol/J rating.
Grow light B also consumes 100W but has 1.5 umol/J rating.
This means grow light B is 50% more efficient at turning electricity into light and effectively will emit 50% more light per consumed watt.
Generally speaking, budget lights will perform at around 0.8 to 1.5 umol/J. High-end lights (usually $500+) can reach twice as high efficacy ratings.
LEDTonic Z2’s efficacy is 1.4 PPF/W (or umol/J) as shown in the test report.
An example sometimes use to describe efficacy is to compare with the size of a car’s engine. Just because the engine is big doesn’t mean the car will go fast, but the engine will definitely burn a lot of fuel. Same thing goes for LED lights. Just because a lamp has high draw wattage doesn’t necessarily mean it produces a lot of light. Look for both efficacy and power draw to understand a lamp’s performance and output.
2. The above example is correct assuming both grow lights have the same color spectrum. I.e. both grow lights emit light of the same color. If you take a quick look among grow lights you will see that some lamps emit a light that is very blue, red, or purple-colored. Whereas your typical desk lamp or ceiling lamp emits a white/yellow-ish light. Right?
Certain light colors, primarily blue and red, are easier to produce. Green, UV and far red, for instance, requires much more electricity to produce.
Therefore many grow light manufacturers opt to have a color spectrum of primarily or even exclusively blue and red light (see image above). While this will produce the maximum amount of light output, this spectrum is very imbalanced and not ideal for plants or for your eyes. It's an unnatural light and irritating to look at for long periods of time. A light color spectrum close to natural sunlight, or at least pink-ish (less heavy on blue and red) is the ideal choice for both plants and humans.
I wrote this above but it's worth repeating: various research says an ideal color spectrum consists of 15-20% blue light, 15-25% green light, and about 60% red for optimal plant growth, health, and photosynthesis.
So, to determine lamp efficiency of a grow lamps, compare the spectrum (make sure it's well balanced) and efficacy (umol/J, PPF/W, or PPE). You want a fair spectrum and high efficacy. Then look at how much electricity (watts) the lamp draws, how much light it puts out (PPFD) and how large area it illuminates. Some lamps will have a high light output but they focus the light into a very small area. This is good if you only grow one plant but not ideal if you have a larger area to cover.
Cross-reference information: compare Amazon listing to website, Youtube, etc.
To finish off this little guide, I'd like to urge you all to think critically and not take any claims made online as facts unless you can verify it. Sometimes an email to the manufacturer asking how they did their test and provide any kind of evidence is enough. Best way is obviously to see indisputable evidence in the form of video test reports that cannot be faked or modified.
Understanding the basics of how lights work and knowing what numbers to look for is necessary for you to make a smart purchase decision.
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