LED grow lights are paving the way for future growers, and with so many now growing under these full spectrum heat-free grow lights, getting to grips with the hard science and why these lights are worth the jump from HID is a necessity. High Times caught up with Paul Krasnowski, the creator of BudMaster LED, to find the answers that many of us are searching for.
High Times: Does “more lumens” not mean “more lighting” when it comes to growing cannabis plants?
Paul Krasnowski: No, not at all and often exactly the opposite is true, It’s all about PAR/PPFD when measuring light for plants. This is basically the amount of photons that are hitting the surface of the leaf. White LED have huge amounts of lumens and much lower PPFD, as they are designed for the human eye curve (generally too low on red 660nm to have the best blooms) and our visual comfort, as compared to mono LED which are used for plant growth that target the exact wavelengths of light the plants need and produce higher PPFD but lower lumens.
HT: How does the pink lighting that many LED lights use cover the full spectrum of the plants?
PK: It doesn’t cover the full spectrum but focuses on covering what is proven to be the colors that drive all the main process in the plants, such as energy production by emitting light in the wavelengths to closely match the chlorophyll, carotenoid and phytochrome absorption curves.
HT: The general hype around LED is that they are good for vegging plants but fall short in the flowering phase. Is that necessarily true and if so why?
PK: It all depends on the lamp, to be honest, and if it has the “power to flower.” You can flower cannabis under any high powered LED lamp, but it’s all about how well you can flower it and if the results will be repeatable and reliable for the years ahead. It’s true there are way more bad LEDs out there than good LEDs, and you just have to look at the LED inside, price and origin of the lamps to be able to make a good decision.
HT: What exactly is PAR and why is it important when growing cannabis?
PK: Photosynthetically Active Radiation is the plant’s version of lumens. We measure in PPFD for plants, which basically tells us how many photons of light are hitting a surface per second per meter squared. So Lumens/Lux are for humans and PAR/PPFD is for plants. People think that the light coming from LED lamps is some strange and complicated thing, but you need to remember that “hey man, it’s just light.”
HT: How can a plant receive all the lighting they need if the LED grow light is at the top of the tent, as advised by many lighting companies?
PK: LEDs are not subject to the “Inverse Square Law,” so we and others design our lamps to be in the top of the tent, out of the way of the grower and the plants so it needs no adjusting. The additional vertical range of LED allows for greater penetration, especially when coupled with a focus and magnify optic that pushes it to exactly where we want it to go. A good optic has at least three points of control and is best for controlling vertical penetration and spread in comparison to an HPS that is great for horizontal penetration and spread.
HT: If these grow lights do not produce much heat, will this not affect the temperatures in my root zone and around the plants?
PK: Yes, the heat is the only thing that LED can’t bring to the party. When switching to LED always re-adjust your environmental controllers to adjust, and if you have cold root zone problems, then consider switching to felt pots.
HT: So many of the LED grow lights are very expensive. How can you justify such a financial investment for a grower who can easily kit out a room with low budget HPS grow lights and currently achieve good harvests this way?
PK: We and no one else can justify anyone spending their hard earned cash, it’s all about what people want and how they want to do things. If your looking to save energy, then switch to LED, but if you just don’t care about your energy consumption, then who are we to preach about climate change. On the upside, 2017 – 2019 will see more than $20 billion spent on horticultural LED in the USA alone, so that should start to drive down the prices of the expensive red and far red LEDs.