Which is the highest yielding grow lamp? What makes one LED grow light higher yielding than another? Is there one lamp that is far superior to the rest?
These are common questions we see online in various forums. In this article, we’ll try to debunk the myths and shed some clarity on the situation.
What determines yield when growing indoors?
This is a question that isn’t as simple as it might appear to be. There isn’t one magical answer or a process that will give you the highest possible yield every time. How our plants grow and develop boils down to five major topics and each has its own sub-topics:
- Nutrients, soil, and watering
- Pot size
- Plant & grow space management (including temperature, humidity, CO2)
A plant grown in a small pot will never be able to grow as big as a plant in a big pot, even if all other aspects are carried out exceptionally.
A plant that’s not given the right amount of nutrients will never be able to grow as big as a plant that’s given just the right mix of nutrients.
Follow my drift? What I’m trying to say is that even the best grow light out there, the one that has the best potential to give the highest possible harvest, will fall short if the other aspects of growing are mismanaged.
But assuming you’re doing everything right, then this is what you need to know about light to get the highest possible yield…
Light : The rule of thumb is: more light = higher yield
This is true to a certain extent. We measure the quantity of light (or light intensity) in a given area as PPFD (sometimes confused with “PAR”). High PPFD = lots of light. Low PPFD = not much light.
PPFD (Photosynthetic Photon Flux Density) is measured in unit µmol/m2/s. We discuss PPFD in detail here
f you’re unfamiliar with the term, all you need to know for now is that light intensity, or PPFD, is measurable and there are general PPFD recommendations for cannabis plants in the indoor growing community.
Just like we measure speed in miles/hour or km/hour, we measure PPFD in µmol/m2/s.
High PPFD would be defined as 500-800 µmol/m2/s. Above 800 µmol/m2/s usually does rather little to the end yield and values above 1200 µmol/m2/s generally do more harm than good.
Mature cannabis plants do well when given high PPFD levels so a lamp that covers as much of the plants’ area as possible with high PPFD will result in high yields.
The answer to how well a lamp covers an area (or a plant) with light intensity (PPFD), the lamp’s light footprint map or PPFD chart should be considered. If these terms are new to you, we have a blog about light footprint maps, also called PFPD chart
Generally speaking, the more light a lamp puts out, the more expensive it will be. Each diode that’s fitted inside the lamp costs money. The more diodes a lamp has, the more powerful driver it needs to power the diodes. This comes at a cost.
To demonstrate what I mean, let’s take a look at three different grow lights. We’ll use one high-end, one mid-end, and one low-end lamp to visualize their performance and how it affects yield.
1- Fluence Spydr – $1500
This is the Rolls Royce of grow lights. It’s incredibly high performing but also very costly. As we see on the light footprint map, the PPFD values are both high (which means the lamp emits a lot of light) and even. I.e. the highest PPFD value is not far from the lowest PPFD value.
The Spydr is able to achieve such high and evenly distributed light intensity due to its design and high end parts.
2- LEDTonic Z5 – $179
LEDTonic makes good LED grow lights and we talk about them sometimes on this site. They present clear and transparent specifications which are easy to use when calculating a grow space needs.
Here’s LEDTonic’s Z5 lamp’s light footprint map inside a 2×2’ (60×60 cm tent) at 12” (30 cm).
We see that the middle of the 2×2’ space is well covered with high PPFD but the outer edges getting a bit less exposure. This is to be expected due to the lamp’s shape and size.
3- Bestva “1000W” – $139
Finally, we have a Bestva lamp. This is one of the many “Chinese Amazon brands” that seem to be popular even though the lamp itself doesn’t really stand out in any way.
We see that the lamp emits a blue/red (BLURPLE) heavy spectrum that doesn’t have much green in it. The provided data is also lacking. Bestva uses a different type of PPFD chart that pretty much only shows the PPFD value in the center spot underneath the lamp, except on one height. It’s impossible to tell how big area this lamp actually covers but the listing says:
“5.1′ x 4.7′ growing area at 24″.
This is far from the truth as even the center PPFD value at 24” isn’t near enough what cannabis plants require during flowering. And the PPFD values off-center will be far, far lower.
This should give you a bit of context on how to judge a grow light and estimate how much yield your plants will produce based on the amount of emitted light.
Conclusion on LED Grow Light Yield
The yield you can expect from a grow lights will depend on the power the lamp consumes in relation to how efficient (high efficacy) it is as well as how well the lamp covers your plants with light.
High-end grow lights are built with good, efficient, parts will generally emit more light per watts consumed compared to a mid-end or low-end grow light. The latter two will, however, be cheaper to buy than a high-end lamp.
Generally speaking, the more a lamp costs, the better it will perform.
Look for the lamp’s light output data or light footprint maps. Check how big an area the lamp covers with higher enough PPFD. The closer the emitted light intensity is to PPFD 600 µmol/m2/s or above, the higher yield you can expect, assuming you take good care of your plant and give it the right mix of nutrients and external conditions.
Lamp brands that we’ve seen perform well are Fluence and Migro in the high-end segment, LEDTonic in the mid-end segment and Mars Hydro in the low-end segment.