Can extra BLUE lighting be added for vegetative stage?

Looking at the spectrums of several LEDS - the red seems intended mainly for flowering, and the blue (mid 400’s nm) range is best for leaves and stem growth.

So is there an advantage to adding a light or two that are high intensity blue ranges during the veggie stage of plant formation?

I’m thinking seriously about augmenting the veggie growth weeks by adding blue led ropes, or floods to the enclosure

In fact - it seems to me one good way to get more light INSIDE bushy plants or group of them would be to trail some LED ropes right down through them - blue part of the spectrum once again, so that the right light is carried directly into the center of growth.

Not that I want to make everything too complicated, but I love looking at my plants anyway and if a thing like that actually does have benefits it would be remarkable!

  • I am an experimenter after all. I love to tinker with new ideas
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Adding the blue light will help, provided you aren’t already at peak photosynthesis rates for your plants. The main issue with the rope style leds is the lack of intensity, so I wouldn’t imagine you would see an explosive difference in growth. But I haven’t really messed with them in any horticulture applications to be sure. It’s still pretty easy to say that your experience will depend mostly on your current saturation levels of blue wavelengths, and the other aspects of your grow required for photosynthesis.

I should note that blue wavelengths have also shown to increase resin production in late flower, so that could be a possible benefit as well. But I really don’t have enough information on them to say whether it’s a good idea or not.


I have low light levels I need to improve anyway (just re-arranged all the lights this morning) and I saw some blue floodlight LED’s I could get and want to try.

~Seriously bright ones, and LED, so the wavelength is not just white light that has a blue cover over it. They are intended for area lighting like X-mas displays and such.

Also spotted some 50-packs of both bright (10W) blue and royal blue LED’s if I feel like taking on a soldering project…

It could be a worthy explore I think.

You’d be surprised. White leds are actually blue leds with a coating to make the light source appear white.

I’ve decided I seriously want to try this! if it works - we can call it “BLUE BLASTING” during the vegetative phase.

I have in mind 2 (two) 30W blue LED floodlights, I may or may not use them both, don’t have them yet. But I think the watts are at the wall - so the output should be huge in a bathtub sized space…

*Just looked it up. They are 30 watt, with an output of 2100 lumens each.

I think I want to mount at least one of them on the bottom pointing up, so they under-light the insides of the plants

20171126_20222120171126_202211 so far im showing a good reaction to them. Only been two days tho two blue and two red. This is only a rough draft of my set-up. Have alot of planning and new material to put together

You would be COMPLETELY surprised with how much heat they do produce. If i put them closer they would hurt the plant

What kind of meter readings do you get next to the plants? The meter I have was under ten bucks at Lowes, I think. I’m shooting for a minimum of mid-range or higher on the light meter

Mount them to some aluminum bar stock, it will dissipate some of the heat away from the plants.

Take your readings from those type of meters with a grain of salt. They barely do the job they are designed for, which isn’t measuring photosynthetic active radiation.

Well thats the thing . the heat is perfect amount as it is. Im just having a ph balance issue right nowreceived_321927808290042

That’s why I grabbed a three way meter, it tells me about that too.

Light level (I found out the far end of the scale, 2,000 , is equal to raw direct sun where I am)

PH (I’ve actually tried making some lemon-water that had a PH of 6 and using that for watering)

  • I used the meter to read the exact PH of the water. I can TREAT the soil by making the water more or less alkalitic or acidic

Moisture - it gives a direct and inarguable reading of when the plants are watered just right, or need some

Comparing the readings from direct sun to what I have on the plants has established my guideline to at least shoot for there. I think another two or three fixtures OF DIFFERENT KINDS (they need only one more like the main one I have now) will ramp it up to the local max.

Tops of some of mine read 1000 - 1500, lower parts read 500 or so. That isn’t good enough since direct sun = 2000

My notion here is like a truck only carrying part of a load: If I don’t have the fullest amount of light on the plants that i can supply them with, they are going to be correspondingly less well grown.

if I have only 65% of the light being delivered (see above) to the plants as natural sunlight would apply, I can only expect the plants to do 65% as well as they should have, or could have.

But MJ does grow in some of the oddest and least advantageous places on earth- from jungles to mountains far in the north and south

@FrikkinFrank it looks like you have some stretching in that plant, but thats just to my newbie eye! Doesnt look like the light is too far away, so i was thinking it may be too little light intensity? Can anyone else weigh in? @bob31 @Donaldj @BIGE


As velcrothumb said, you have a bit of stretching going on. The tallness of the stem will undoubtedly lead to weakness. If this were my plant, I would build up soil, or plant her deeper so the stem is supported. Then I would add a fan to the area that gently blows it a bit to strengthen it up.


@VelcroThumb and @Tr33 have you covered @Bman8890
stay on top of your ph
get some support and small breeze on seedling


Oh i have a fan set-up . Im just a idiot and repotted it into a bigger container but not a 5 gallon bucket so if im to repot it and repot it to where just the leaves are above the soil this will make it my third time and im scared it will stress it. So im gonna let the roots become rootbound then ill let it dry out and repot it into a 5 gal. Just made a poor decision

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@Bman8890 I did mean to suggest that you might have something handy to support her. Like a tomato stake or something similar.

And i agree to wait, but lets transplant before she gets root bound. By the time you realize, it’s root bound she will get very stressed and its best i think to minimize any further stress.

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When do you think would be a good time to do the transplant. Im gonna set up a support system. Im working a grow box atm. Reflector tape and what not. Bought more leds also. Just trying to figure out how big i want the box and if the adhesive from the tape Will harm the plant. Also im starting to think the light is see through on the bucket and the roots are getting light so its damaging them. Not sure tho but im gonna get sum black tape and tape the bucket outside. Until i repot

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I wouldn’t use tape on the plant @Bman8890

just a thin stake and a loop of string

Remind me how long ago you last transplanted. i know it wasn’t a long time ago. I would say two weeks after the last transplant would be right. I would bury her stem right up to within 2 inches of the low leaves.

I would say just about two weeks .

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