Best Spectrums for Each Stage of Growth

One of the benefits of growing with LEDs is being able to fine tune your spectrum. So that leads me to the question, what is the best spectrum for each stage of plant growth?

Obviously there will be differing opinions but I was hoping to see what all of you LED connoisseurs had to say.

So what are the best spectrums/color temperatures for:

Seedings/Cuttings (is there a difference between the two?)
Vegetation
Pre-Flower
Flower
Ripening (last two weeks)

Generally speaking. The best spectrum for each stage is relative to personal opinion. If you browse the forum more you will find some growers prefer 3500k for the entire grow. While others may prefer 5600k for the entire vegetative phase (Seedling / cutting and vegetation) and may prefer 3000k for the entire flowering phase (Pre-flower, flower, and ripening).

More specifically If a grower were trying to mimic what happens outdoors.... 5600k to promote root development during the seedling / clone and vegetative phases. 3500k and/or 3000k for the preflower and flowering phase, and 2700k for the ripening phase.

3500K start to finish.

Haven't personally tried it yet, but 3000K 90 CRI looks to be the most productive spectrum on paper, IMO.

I'm going to be honest. I don't totally understand kelvin. What is the difference between 5600k and 3500k. With non white LEDs, it's easy for me to understand something along the lines of 70% blue 20% red 5% white 5%IR for veg. But how do you compare kelvin? Is there a similar way?

Smoke-A-Cola said:

I'm going to be honest. I don't totally understand kelvin. What is the difference between 5600k and 3500k. With non white LEDs, it's easy for me to understand something along the lines of 70% blue 20% red 5% white 5%IR for veg. But how do you compare kelvin? Is there a similar way?

Click to expand...

High k; More blue.
Low k; more red.

This article may be helpful......https://blog.grobo.io/how-does-different-colour-light-affect-plant-growth-6cfd16eba7b2#.cf9zzd6ag

Smoke-A-Cola said:

One of the benefits of growing with LEDs is being able to fine tune your spectrum. So that leads me to the question, what is the best spectrum for each stage of plant growth?

Obviously there will be differing opinions but I was hoping to see what all of you LED connoisseurs had to say.

So what are the best spectrums/color temperatures for:

Seedings/Cuttings (is there a difference between the two?)
Vegetation
Pre-Flower
Flower
Ripening (last two weeks)

Click to expand...

IMO big difference between seedlings in cuttings. That is of course if we are talking about rooted cuttings.

Hos specific are you looking for?

We all know, blue for veg and red for flower...

I had not considered breaking it out into the smaller stages... that is interesting... super spectrum focus...

I guess then it's more what nm for each of those stages? I want to see an experiment!

thewanderingjack said:

Hos specific are you looking for?

We all know, blue for veg and red for flower...

I had not considered breaking it out into the smaller stages... that is interesting... super spectrum focus...

I guess then it's more what nm for each of those stages? I want to see an experiment!

Click to expand...

As specific as possible. That was exactly what I was thinking. We all know Blue=Veg Red=Bloom. But what is really the most ideal? And then what about seedlings? and cuttings? And early Veg? And late flower?

I know UVB can be great for late flower. IR is supposed to reduce stretching, should in be used it early veg? What about UV/IR for cuttings, should they be cut out completely? How many watts is too much for a seedling? Etc...

Smoke-A-Cola said:

As specific as possible. That was exactly what I was thinking. We all know Blue=Veg Red=Bloom. But what is really the most ideal? And then what about seedlings? and cuttings? And early Veg? And late flower?

I know UVB can be great for late flower. IR is supposed to reduce stretching, should in be used it early veg? What about UV/IR for cuttings, should they be cut out completely? How many watts is too much for a seedling? Etc...

Click to expand...

Yeah, very interesting... I hear different things about UV/IR from people, haven't looked into it enough to make up my mind.

The UV/IR wih cuttings is very interesting too... no idea there... I guess, if no info is specifically available we have to look at exactly what the light does, and what the plants doing at that stage, then guess at what they may do together. I have a UVB bulb I was thinking of playing with... I use it for myself (vitamin D deficiency) and will be purchasing a multipurpose UV in the future... and an IR lamp is also within my budget and use ( I love a good heat lamp... we get little sun where I live, and it's cold).

This is now on my list of near future experiments (my other involves citrus acids for growth)

Or the seedlings... hmm... in my experience it has been the more the better so long as intensity and heat were conrolled. I put 20+ watts CFL right down by my seedling ( like 3 inches?... I sprouted by letting the hood of the clamp lamp sit on the soil creating a dome, and raised it slowly and proportionally over time til I hit the "sweet spot" for me (best coverage and intensity).

I am often curious about minimums... how many watts do you need to sprout well. How much water per plant mass? etc etc