One of the great growing myths is that you need more blue light in veg. This is a carry-over from the days when everyone was growing under HPS. HPS has very little blue light and no UV light, and so plants would often stretch during the vegetative stage compared to being grown under MH, which does have UV and higher amounts of blue light. However, even though plants stretched more under HPS, they actually grew faster due to the higher amount of orange/red and far red light that promotes growth. Blue, violet and UV light simply counter the shade-avoidance response in plants that causes them to stretch under higher levels of far red light.
We have combined a higher amount of red and far red light for growth with the optimum amount of blue, violet, and UVA light to counter stretch. Whilst the current spectrum is 3000K and will stretch slightly more than under 5000K etc, it will grow faster and healthier. We first noticed this when building vegetative strip lighting using Samsung diodes that the 4000K LEDs outperformed the 5000K and had fewer health issues due to the reduced amount of blue light. Too much blue can cause prolonged stomatal opening in response to leaf temperature rises, as the chloroplasts can only absorb so much blue light before it starts to build up as heat. This often leads to lighter coloured leaves, yellowing and red stems (caused by pigments that build up as part of the plant’s stress response) due to light stress and an imbalance of calcium, magnesium and potassium due to over-transpiration. A lot of growers would report problems in growth that went away in flower when the only thing that changed was the light (they were still using the same nutrient formula in the first two weeks of flower). It was through this we discovered than the 5000K LEDs – which have 33% or more blue light – were doing more harm than good.
This is all a long way of saying that LEDs have enough blue in them already to counter stretch and benefit from higher amounts of red – which is why we have seen better results from 3000-4000K than we have with 5000K. In addition to this, our High Light 420 boards have 0.5% UVA and around 5% light from 400-440nm which other LEDs do not have, meaning our 3000K lights cause less stretch than other 3000K LEDs.
