• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

is additional lighting from "underneath" a bad idea?

shamanshawn

shamanshawn

Member
im growing some white widows in soil under a 600 watt hps. a week into flowering i decided to add some additional light near the bottom of the plants; 27 watt cfls hanging about halfway down the plants & 2-40 watt 4 footers shinning up from underneath the plants. ive been told since i did this that light shinning on the undersides of leaves is bad for them. i'd like to hear what the good people here at RIU think.
 
W

weedsLV

Active Member
Sounds weird I think they would b more useful on the sides and on top then the bottom they grow towards the light so that might confuse n stress em
 
H

HSA

Well-Known Member
Shamanshawn: for what it's worth, I've been growing with Aerogardens and if you know anything about them; they're a compact, patented, self contained growing system with a small reservoir and high intensity CFL lighting. They're limited to a practical growing height of 23 inches and everyone tries adding side lighting for better plant growth. I started using mirrors to reflect the light back up to the lower portions of the plants. It worked fine until I broke one. What a mess. Then I made Mylar covered reflectors and they worked great. I got buds all the way down to the planting deck with the same amount of light God and Aerogarden gave me. To do that I had to light up the bottom as well as the top and there was no problem so I wouldn't worry.
 
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novice11

Active Member
Okay, I'm new and a bit confused about this side-lighting issue.

I'm running 8 tube 48" T5s in veg. Everything I have read says that CFL/florescent need to be super close to the plants to be effective. So if one wants to use T5s for a sidelight as well, do you have to get them right next to the plants on each side to be effective? Is there any point to sidelighting w/ T5s if they are going to be 6 or 9 inches away?
 
hgkdehs

hgkdehs

Active Member
HSA said:
Shamanshawn: for what it's worth, I've been growing with Aerogardens and if you know anything about them; they're a compact, patented, self contained growing system with a small reservoir and high intensity CFL lighting. They're limited to a practical growing height of 23 inches and everyone tries adding side lighting for better plant growth. I started using mirrors to reflect the light back up to the lower portions of the plants. It worked fine until I broke one. What a mess. Then I made Mylar covered reflectors and they worked great. I got buds all the way down to the planting deck with the same amount of light God and Aerogarden gave me. To do that I had to light up the bottom as well as the top and there was no problem so I wouldn't worry.
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"high intensity cfls"? Lol
 
Dankster4Life

Dankster4Life

Well-Known Member
Any xtra light is going to help.Tossing your cfls under the canopy will give the light deprived stuff some help.You will be fine.The closer you can get them the better.

I don't get why some one would tell you "it's bad for them",bad advice.
 
shamanshawn

shamanshawn

Member
hey, thank u all for ur advice. i had no idea u can get 4800 lumens from a cfl! im glad to know that. i should have explained myself better tho. i do agree that 'side lighting' does work, ive seen its results myself. what i was told was that leaves have 2 different sides for a reason, that there are diff chemicals on the underside than on the top side & that direct light to the undersides of leaves is somehow bad for them. that could be true, idk, but i dont think that my little bit of fluorescent light coming from underneath is goin to do any harm. & as far as my cfl's for side lighting, they're working fine. i believe my 600 watt hps is giving my plants enough light, i just didnt want to have extra bulbs laying around not being used, so im going to keep using them. thanks again for the replies!
 
MountainManGanjaGrower

MountainManGanjaGrower

Active Member
well if its from directly underneath I'm not sure they would be able to absorb it. It wouldn't be bad, but I would recommend side lighting like it seems everyone is saying. When a plant makes it's leaves I think the stuff called auxin is what is basically the plants nervous system and reacts to the abiotic factors, and the kind in the leaf always pushes the top layer, the choloroplast containing cell side, towards the light and strengthens it from behind(i'm not 100% on that but I'm pretty sure i'm close enough haha you might want to check for yourself).
So if anything I it would help, I don't think in ANY way it would hurt them, the only way to know is to give it a try.
 
dajosh42069

dajosh42069

Well-Known Member
Compare 4800 lumens from 55W's though, compared to an HID, that's not as efficient. But I myself used a 55W CFL for supplemental lighting during flower. Worked nicely.
 
TiloGrow

TiloGrow

Member
Dankster4Life said:
Any xtra light is going to help.Tossing your cfls under the canopy will give the light deprived stuff some help.You will be fine.The closer you can get them the better.

I don't get why some one would tell you "it's bad for them",bad advice.
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ha you have 420 posts... random
 
N

novice11

Active Member
One of the reason I'm using T5s is the heat issue. I'm doing a closet grow, and even the T5 warms it up. I really don't know what I would do if I had lights that were really throwing out some heat.
 
Prefontaine

Prefontaine

Well-Known Member
shamanshawn said:
hey, thank u all for ur advice. i had no idea u can get 4800 lumens from a cfl! im glad to know that. i should have explained myself better tho. i do agree that 'side lighting' does work, ive seen its results myself. what i was told was that leaves have 2 different sides for a reason, that there are diff chemicals on the underside than on the top side & that direct light to the undersides of leaves is somehow bad for them. that could be true, idk, but i dont think that my little bit of fluorescent light coming from underneath is goin to do any harm. & as far as my cfl's for side lighting, they're working fine. i believe my 600 watt hps is giving my plants enough light, i just didnt want to have extra bulbs laying around not being used, so im going to keep using them. thanks again for the replies!
Click to expand...
Ok so the top of the leaf is generally a little waxy and darker green than the bottom this is because the top of the leaf heats up a little bit, so the wax needs to protect from evaporation, while the dark green is absorbing light radiation. the bottom of the leaf is where the respiration takes place, if you use a high intensity light from beneath it will mess with the respiration of the leaf, that said, light from beneath will be absorbed by the leaf but at much lower efficiency than from above, more importantly placing the light within the plan would allow for maximum absorption of light per bulb, so just dont start a fire or scrorch your plants and you'll be doing fine.
 
shamanshawn

shamanshawn

Member
its been well over a week now & i dont see any harm from the fluoros shinning up from under the plants. the white widows show no real change at all, but i have 1 bushy afghan thats turning its lower leaves under so the tops of the leaves are facing the light. its damned amazing how these plants act sometimes. once again, I thank u all for taking time to give me ur advice. im sure i'll need it again one day.
 
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