What’s true. What’s not
Perhaps the biggest misleading statement used by LED sellers is the term “equivalent watts”.
There is no such thing.
Watts are watts. And when we at Grow Lights Australia use the term “watts”, we are referring to the exact amount of power (wattage) supplying the boards and/or driver.
High Light boards are maximum rated for 225W. But they can be driven at much lower wattages to increase their efficiency. Add to this the power consumed by the driver itself – which might be an additional 5-7% – and you have the total system wattage. This can be measured at the wall using a simple watt or power meter available at most hardware and electrical stores.
Two High Lights driven at 350-400W (175-200W each) will replace a 600W HPS lamp in terms of documented yields.
That does not mean a 350W High Light LED fixture is a “600W equivalent”. It simply means you can get the same results with two High Light boards using 2/3 the power of a HPS lamp. And 2/3 the power also means 2/3 the heat – heat that doesn’t have to be cooled with air-conditioning, which uses additional power.
Every year, the gap between LED and HID efficiency is growing.
It is worth noting that LED drivers are just as efficient as the most efficient HID digital ballasts at around 95% – and much more efficient than cheaper digital and magnetic ballasts that can consume more than 10% of all power.
It is also worth noting that LEDs do not have an initial power spike during start-up like many HID ballasts, so their current draw remains stable. This is an important consideration when designing a grow room, as you do not need to allow for extra current and fusing for short periods of the day during start-up.
Like the first myth, this one is due to exaggerated claims by some LED manufacturers that couldn’t live up to their hype.
High-quality LED horticultural lights are in fact better for flowering than traditional HPS, MH and CMH lamps.
The reason is simple: LEDs are able to incorporate more red light – including red, deep red and far red from 600nm-750nm – that is responsible for accelerated photosynthesis and flower development, and more blue light that is responsible for compact structure, thicker leaves, stronger stems, and terpene (essential oil) production.
High Lights have been specifically designed as flowering boards – hence why the blend of high-efficiency LEDs incorporate more red light, a more balanced blue spectrum, and near-UV and UVA light to facilitate faster flowering growth and higher levels of terpenes.
High Lights can be used during the vegetative or growth phase – and will actually grow faster than cool white or higher Kelvin temperature LEDs (5000K etc) – but may not be as suited to leafy greens and non-flowering plants as they are to flowering and fruiting varieties due to the higher amount of red and lower amount of blue.
Ever wondered why the first LED grow lights were a mix of red and blue diodes commonly (and derogatively) referred to as “blurple”?
Ever wondered why they didn’t work so well?
Poor efficiency aside, somewhere along the line someone decided that because plants were green, green light was not useful for growth because plants reflected most of it.
This is not true.
Recent scientific studies have shown that in fact green is the most efficient spectrum for plants to photosynthesise, as it penetrates deeper into the cell structure and is responsible for plant health and immune system response.
It is precisely because green light is so efficient that most plants reflect it into the lower canopy to sustain growth when direct sunlight is not available.
In simple terms, blue light (shorter wavelength) carries the most energy but also scatters the most (which is why the sky is blue). More energetic radiation – such as deep blue light, near-UV, UVA and UVB – can elicit stress responses in plants that cause them to produce more compounds to protect their DNA, such as terpenes (essential oils) and active substances (such as cannabinoids).
Green light (medium wavelength) carries more energy than red light (longer wavelength) and also penetrates deeper into the cell structure. This means that, even though red light is more efficiently photosynthesised by plant chloroplasts on the leaf surface, green light penetrates to activate more chloroplasts under the surface which combine to increase leaf photosynthesis as a whole.
Red light is the least energetic light, but is the easiest to photosynthesis for plants. It is responsible for fruiting, flowering and shade avoidance, which causes plants to stretch in an effort to find more blue light (red and far red light penetrate deeper into the canopy, which triggers the plant to grow in search of more direct sunlight).
Far red light also has a role to play in regulating growth hormones and determining when a plant begins to fruit or flower. Combined with red light, it can accelerate photosynthesis in a symbiotic relationship documented as the Emerson Effect.
As you can see, spectrum plays a very important role in plant growth and flowering – and that is where LEDs have the advantage of being able to be “tuned” for optimal growth for different plant varieties.