INSIGHT FOR NEWBS ON LIGHT PENETRATION.

gardengardian7

Well-Known Member
Removing leaves is not the only method of decreasing shading and increasing light penetration. Using light movers, you can supply light at a variety of angles. This can reduce stretch, and light otherwise shaded leaves. Oscillating fans can be aimed to flutter leaves, allowing light to penetrate deeper into the canopy. Reflective material on the walls will also help to redirect wasted light at angles advantageous to lower leaves. For smaller grow rooms, plants can be set at different levels like stadium seating. In theory, this works great; but it is difficult to implement in larger grow rooms, and virtually impossible with many hydroponic systems.

The best answer for improving light penetration is simply to grow shorter marijuana plants. This is one reason that “See of Green” gardens yield so well. With taller plants, the majority of the bottom branches end up in shade. Even if light did penetrate the upper leaves, the lumens reaching the lower branches are so diminished that they yield poorly anyway.

What have you learned?

Do not remove leaves indiscriminately.

Do not remove young leaves unless heavily damaged by bugs or molds.

Do not sacrifice healthy leaves near the light for the sake of lower leaves.

Remove leaves that are beginning to yellow.

Do not remove mature leaves if you have a weak root system.

Use light movers, oscillating fans, and reflective material to improve light penetration

Grow your plants short to keep all the branches as close to the lights source as possible

Use selective pruning to remove sucker shoots that use up valuable plant energy

One final thing to remember: when you remove leaves from your plants, be sure to remove them from the grow room. Piles of leaves in the corner, or in a garbage can, will likely begin to harbor pests or molds. The last thing you want is a waste basket full of botrytis spreading spores through your garden and ruining your harvest.
 

xSwimToTheMoon

Well-Known Member
Excellent post. I'm mid way through flower and have a few uneven plants. I hope to employ some new techniques next Go.

I like the part about waste in the grow area. Especially with spring here.
 

TedeBoy

Well-Known Member
I agree, however I'd add that sidelighting is another solution to plants grown too large for the top lighting. I'm impressed with sidelighting, but it's not feasible for large grows. It takes some work in a 4x4 tent. I use ordinary Cree LED lightbulbs from Home Depot.
AZ...my space has 4 autos in a 3'x3'x5' space with a Mars II 900W overhead. Plants are at 5 weeks about 20" tall and forming flowers. Would you recommend I use side lighting and if so what wattage cree bulbs? How to place them in my crowded space? What fixture to house the bulbs? How many?
 

az2000

Well-Known Member
AZ...my space has 4 autos in a 3'x3'x5' space with a Mars II 900W overhead. ... Would you recommend I use side lighting ...?
In your case you already have 55w/sq ft (if your light is 500w actual). I think sidelight always helps. But, when you reach 55w/sq ft with an epiled, it would be a diminishing return. It would be ideal to supply 20-30w/sq ft epiled toplight, and 10-20w/sq ft sidelight.

To explain the wattages, epiled isn't as efficient as cree. And, sidelight adds efficiency (IMO). For shorter plants (your shorter 5' tall space) 45-50w/sq ft should be optimal (the point of diminishing returns) for epiled toplight. If it were a Cree/Osram/Phillips toplight, 30-35w/sq ft would be optimal. I like to do 50-70% toplight, 30-50% sidelight. But, when using epiled on top and Cree on the side, Cree being more efficient (and more coverage being more efficient, IMO), the toplight can be reduced. I get down to about 10-20w/sq ft toplight using Cree, doing 10w/sq ft sidelight. (I just had great results at 22w/sq ft using Cree PAR38 spots on top and Cree 9.5w around the side.).

If you had half the wattage on top, some sidelight would be beneficial and more efficient (IMO) than supplying all that wattage from the top. I'd also advise you to have multiple points of top light instead of a single powerful fixture. Same principle as sidelighting: you get more coverage, more angles of light. (Additionally, when, not if, the fixture fails you won't struggle with total darkness.).

The link in the prior post shows how sidelighting can be mounted. (There's also SMD5730 strip lights which are slightly more efficient than Cree lightbulbs. Those can be mounted in a variety of ways, creating mini panels. They run cool, literally can be inserted into the plant.).
 

TedeBoy

Well-Known Member
In your case you already have 55w/sq ft (if your light is 500w actual). I think sidelight always helps. But, when you reach 55w/sq ft with an epiled, it would be a diminishing return. It would be ideal to supply 20-30w/sq ft epiled toplight, and 10-20w/sq ft sidelight.

To explain the wattages, epiled isn't as efficient as cree. And, sidelight adds efficiency (IMO). For shorter plants (your shorter 5' tall space) 45-50w/sq ft should be optimal (the point of diminishing returns) for epiled toplight. If it were a Cree/Osram/Phillips toplight, 30-35w/sq ft would be optimal. I like to do 50-70% toplight, 30-50% sidelight. But, when using epiled on top and Cree on the side, Cree being more efficient (and more coverage being more efficient, IMO), the toplight can be reduced. I get down to about 10-20w/sq ft toplight using Cree, doing 10w/sq ft sidelight. (I just had great results at 22w/sq ft using Cree PAR38 spots on top and Cree 9.5w around the side.).

If you had half the wattage on top, some sidelight would be beneficial and more efficient (IMO) than supplying all that wattage from the top. I'd also advise you to have multiple points of top light instead of a single powerful fixture. Same principle as sidelighting: you get more coverage, more angles of light. (Additionally, when, not if, the fixture fails you won't struggle with total darkness.).

The link in the prior post shows how sidelighting can be mounted. (There's also SMD5730 strip lights which are slightly more efficient than Cree lightbulbs. Those can be mounted in a variety of ways, creating mini panels. They run cool, literally can be inserted into the plant.).
Thank you man. My Mars Hydro II 900w LED draws about 411W at the plug divided by 9 is 45.6 watts per square foot. They seem to be okay so I may want to let it ride?
 

az2000

Well-Known Member
Thank you man. My Mars Hydro II 900w LED draws about 411W at the plug divided by 9 is 45.6 watts per square foot. They seem to be okay so I may want to let it ride?
Yes, that's about the right intensity of light for epiled for that height of plant, with typical single-source top lighting.

If you used a fixture with Cree diodes, 35w/sq ft would be equivalent. And then, when providing watts through sidelighting, you can get equivalent with 25-30w/sq ft. (That's my experience so far.).

It's a tradeoff between labor or electricity. Some people may find it's easier to just throw a lot of watts from the top and be done with it. I like trying to squeeze more from less. But, it can be tedious getting it setup, adding lights as the plant gets larger, etc. Some people may not want to plan for sidelighting, but sidelighting can be useful if someone overgrows their toplight. Instead of cutting off lower growth, add sidelight. Your popcorn buds will be real buds.
 

mr2shim

Well-Known Member
I agree with this, but at the same time I DO remove leaves. But if someone asks about removing fan leaves, I tell them "if you have to ask the answer is no"
 

Chester da Horse

Well-Known Member
any comments on my freshly installed side lighting? do you see any room for improvement?
Added supplemental CFLs.jpeg

I can't afford LED bulbs and I had these CFLs lying around (4x24w on the left, 2x45w on right, all cool daylight to complement my HPS toplight)

Using styrofoam as a makeshift reflector... better than nothing right?
 

WeedFreak78

Well-Known Member
How about explaining, or linking to, something relevant to light penetration? Like inverse square law and how that applies. This is a post about defoliation effects on light penetration.....
 

gardengardian7

Well-Known Member
How about explaining, or linking to, something relevant to light penetration? Like inverse square law and how that applies. This is a post about defoliation effects on light penetration.....
So, do you mind giving us the good knowledge Mr Freak. We need it. You can help make the post relevant.
 

gardengardian7

Well-Known Member
any comments on my freshly installed side lighting? do you see any room for improvement?
View attachment 3392158

I can't afford LED bulbs and I had these CFLs lying around (4x24w on the left, 2x45w on right, all cool daylight to complement my HPS toplight)

Using styrofoam as a makeshift reflector... better than nothing right?
Looking cozy and good room for side lighting. I guess it depend on the style of growing. Because Youre not doing a canopy, so your style is appropriate with your side lighting. But us t5ers, fluorescent and led have to really maneuver side lighting. Well i guess depending too on grow space and number of plants. Im new to t5. And I wasnt accurate as I would like to be using a t5. I was aware that limited lumens is coming from up top and that i would also have depend on side lighting. I kind of got screwed because some other facters like the net i got was big enough to put a bush in.. lol got the wrong trellis net, so I had no choice but to do what i needed to do as far as making this canopy like grow successful as possible. See you can turn your plants if need be. But i cant. So your operation is good.
 

Boatguy

Well-Known Member
I have some phillips lumiled strips as vertical lighting and they seem to be working well. Efficiency is good and their space consumption is very small. Light wise they are the equivalent of a fluorescent maybe alittle better but their size is much much smaller. IMG_0430.JPG
 

gardengardian7

Well-Known Member
I have some phillips lumiled strips as vertical lighting and they seem to be working well. Efficiency is good and their space consumption is very small. Light wise they are the equivalent of a fluorescent maybe alittle better but their size is much much smaller. View attachment 3392501
I just saw some of those when i looked t5 pics. I want some of those. I think im going to get some of those in a few weeks. Going to look on amazon now...
 
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