Thanks Bode. Things are finally moving along now. Next weekend, maybe earlier, they will be topped for quadding.
Haha, it's an automated watering system I'm trying out. Here's the breakdown:
@TriangleCheese hey brother are you able to link a study saying 3000k and 3500k doesn't have enough blue in it for your plants to reap the benefits? Cuz I'm not finding anything that says you need THAT MUCH blue like 6500k.. If your veg. setup has a color temperature equal or less than 6500K(blue heavy spectrum) and can provide around 900-1000 micro moles of photon density, then yes you can use only the veg. switch. But if you don't provide enough photons for your plants, then both the quality and yield would suffer.
Another thing that we can discuss is the optimal spectrum for bloom. Forget about the Watts used for a second and consider that we have one 3000K(yellow and orange heavy) and one 6500K(blue heavy) LED fixture, providing the same photon density of 1000 micro moles. The only different thing would be the spectrum. Since these spectrums have different wavelength compositions, identical plants would turn out different under these two different setups. 3000K setup would produce longer and thinner colas but 6500K setup would produce denser and fatter buds. The smokable weight would still be higher on 3000K but the quality would definitely be better with the 6500K, since it is a blue heavy spectrum. About the last week veg. switch, I don't think it would have a magnificent effect on quality so the only thing I might do on the last week would probably be stacking both switches together and move the lights away if the light gets too bright for the plants.
So why don't we use 6500K through all the flowering? Because, besides quality we also need a big yield and therefore we need to use a spectrum in between. We need a fair amount of blue and we don't have that much in 3000K. 3500K is OK but the sweet spot for blue starts on 4000K. You'll have plenty of blue and red if you go with 4000K. Best thing you can do is boost such circuit with some 660nm to increase the PPFD and tune your lights perfectly for flowering. My fixtures provide color temperature of 3887K with 4000K+660nm diodes and that is my sweet spot. I get high amount of top shelf buds all the time. I'll drop some pictures of my plants if @Mr. Sauga doesn't mindI grew both the Pink Kush and the Purple Punch under 3000K and the result was nowhere near.
Using Blue Light in Cultivation
TL;DR: Blue light is a key wavelength for photosynthesis and growth. So buy lights that have blue light, whether for growing cannabis or any other kinds of plants.
Whether you’re buying a light for a houseplant, an indoor cannabis grow, or large-scale plant production, it can be challenging to pick the right light. There are multiple factors to consider and conflicting information online. While light intensity is the most important factor, spectrum can be important too. This article explains how blue wavelengths impact plant growth, based on peer-reviewed research.
Blue Light and Photosynthesis
Blue light is radiation with wavelengths between 450 – 495 nm. It strongly impacts photosynthesis and vegetative growth [1]. This is because the wavelengths of the blue correspond to the wavelengths that photosynthetic pigments absorb the most. Chlorophylls and carotenoids, two key groups of photosynthetic pigments, absorb blue light and convert into chemical energy (sugar) that can be used for plant growth [2].
Even though blue wavelengths are highly absorbed by chlorophylls and carotenoids, they are slightly less effective than red light for driving photosynthesis [3]. This can be explained by the absorption and action spectrums of photosynthesis (see Figure 1). The absorption spectrum (dotted line) shows which wavelengths are absorbed by chlorophyll and other pigments. On the other hand, the action spectrum (solid line) shows the photosynthesis rate for each wavelength.
Figure 1: The absorption spectrum of chlorophylls and beta carotene correlates with photosynthetic output. Red light is slightly more effective than blue light for driving photosynthesis. (Modified from HyperPhysics Biology)
The key is to compare the difference between the dotted and solid lines. The gap between the two lines in the 450 – 495 nm range means that plants absorb large amounts of blue light, but not all of it is converted into sugar energy. This leaves us to wonder — where does the rest of the blue light go? Some of it gets absorbed by lower-efficiency pigments (like anthocyanin) that don’t contribute to photosynthesis.
This doesn’t mean that plants don’t need blue light — they do. But even better things happen when blue light is paired with red. Photosynthesis happens faster, plants product more protein, more pigments, more leaves, and they generally grow bigger [5, 6, 7, 8, 9].
Blue Light and Stomatal Conductance
Aside from photosynthesis, blue light has other effects on plants. Blue wavelengths increase stomatal conductance. Stomatal conductance is the process of gasses (like CO2) entering and exiting leaves through the pores in the leaf’s surface. Blue light impacts stomatal conductance by increasing the number, density, and size of stomata [10].
If the effects on photosynthesis didn’t convince you that blue wavelengths are important, this next part might. Gas exchange through the pores is critical for both photosynthesis and leaf cooling. Thus, providing plants with enough blue light is necessary for them to be able to control their temperature.
Relationship to Stem Stretching
Tall, leggy plants are undesirable because the plant can easily fall over. Plants often look nicer when they have a short stem and compact leaves. Stretching happens when a plant doesn’t get enough light and so it grows taller to capture more.
Blue wavelengths are a key way that a plant senses how much light it’s getting. Providing a plant with more blue light helps ensure that the stems stay short. Along similar lines, blue light can also decrease petiole length [3]. Petioles are the small stems connecting the leaves to the stem. For this reason, plants that are given more blue light tend to have more compact leaves [6, 14].
Blue Light and Seedling Growth
Blue light also has an effect on seedling growth: it increases seedling size and the antioxidant concentration [15, 16]. Antioxidants protect plants from UV rays and harmful reactive compounds that can cause major problems for photosynthesis and flowering. Thus, increasing antioxidants in plants may be one way to offset the stresses that come along with intense photosynthesis rates. In addition, blue wavelengths increases the sprouting rate, fresh weight, and protein content compared to other colours of light [15].
Effect on Flowering
Blue light impacts flowering in two main ways: timing of flowering and flower weight. Through the action of chryptochrome (a light receptor in plants), blue wavelengths can sometimes regulate flowering time. How blue light impacts flowering depends on light intensity and whether the plant is a “long-day” or “short-day” plant. Generally, blue wavelengths cause flowering to happen earlier in long-day plants and later in short-day plants. For example, mustard is a long-day plant and exposing it to blue light causes flowering to happen 20 days earlier than it normally would [17]. In other species, blue wavelengths have no effect on flowering [18]. For some flowers, pea plants, and violets, blue light doesn’t change flowering time at all [18]!
Impact on Cannabinoids Production
Last, but not least, some recent research shows that blue light may effect cannabinoid production in cannabis. One study looked at the effect of light quality on the yield of THC and other cannabinoids in cannabis cultivation. Plants grown using LEDs (which had 6 – 16% more blue wavelengths than HPS lamps) had about 38% more THC compared to those grown under HPS lamps [12]. Cannabis plants grown under LED lights also had higher concentrations of CBD, THCV, CBG, and cannabinoids [12]. The authors suggested that UV-A and blue wavelengths might cause the plant to produce more CBG (a precursor of THC and other cannabinoids). The mechanisms underlying the effect of blue wavelengths on the cannabinoid pathways will also require further research.
Don't mind at all. However it may be better off in the LED Light forum before it gets too deep for this journal. Good info, thank you!
. You certainly know how to dial in the right shade of green regardless of what nutes you're running (PM notwithstanding of course), and dialing up the lux is going to send them to the moon, Alice...to the moon!
I did! Due to being busy really, but I wanted to vigorously grow them for a bit before moving them. They were showing deficiencies so it had to be done, or I may have waited another week. I'm going to hate to top them as they stems are so thick up top.Those plants are gorgeous, and you waited a bit longer than I to upcan from the solo cups
Thank you! It's all about eating right. Understand what's in the nutes, and stick with the levels that have worked in the past.
Hiya Sunny!Aloha Mr. Sauga
Not sure how I got here from the Sauga that never ends but I’m sure glad I did as usual
Stop by anytime, in any condition .
Oh dear that is covering a wide spectrum my friend.. does this mean clothing is optional?Hiya Sunny!
Glad you made it! I hope all is well.
LOLOL! I started a new job just before I went corporate. I even went as far as hooking up that Frankenstein thingy
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@TriangleCheese hey brother are you able to link a study saying 3000k and 3500k doesn't have enough blue in it for your plants to reap the benefits? Cuz I'm not finding anything that says you need THAT MUCH blue like 6500k.
This article contains info from over 15 scientific case studies in the subject:
So I don't see anywhere it actually says you need a 6500 Kelvin light to grow better weed or 3000k doesn't have enough blue.......it just says more blue spectrum from LED than HPS gives you almost 38% more thc
Below is Samsung's latest quantum board diode.
The LM301H 90cri
(Most boards run 80 cri I chose 90cri as a reference because it's a superior spectrum)
Now if you look below there is no difference between 5700k, 5000k and 4000k in the blue spectrum or intensity.
(And for the record an EYE HORTILUX HPS bulb still has 30% intensity at 450nm blue)
And since that study says all u need is 16% more blue than HPS to get 38% more THC,
I'm failing to see where this massive spike in blue wavelengths gives you a much superior product.
Maybe you read up on some studies that I can't personally find and if you have that info id love to read it
Apologies @Mr. Sauga hope this was worthy of going off topic for a moment
Ya, the summer to forget! Thanks Boo. I had lots of fun too, and still do. Have a great Saturday and a lovely Sunday. I hope your Monday is as good as your Tuesday to Friday will be, and then I wish you a great Saturday again!I‘ve only known MrS. since May-ish of last year. I think he was on a sabbatical at that time and was hangin’ with us full time....and it was a FUN Summer! It is still fun and I appreciate when you are here MrS!
