Cob light penetration and plant height question

[wardo]

I'm new to cob but with hps you can get plants pretty tall. Cobs of course have less penetration, or so I'm told. If I have 4 50 watt Crees, how big should I get my plants before flower? I have 7ft of vertical space, including space for the light.

[Jolly Green Giant]

welcome to the forum first off
( second.. this is post #420 for me )

I would say it depends on your style of growing and strain dependant...

I like to keep shorter plants that are trained to fill a space... I use a 5x5x7 tent, but use a 4x4 tray on the floor.. with a scrog net roughly 3' off the floor. with my light( diy hlg550 equivalent) roughly 18-20" above the scrog, I still have a little over 2' above the light. I have buds forming at pot level! ( roughly 40" from light down thru canopy) I flip mine after I weave them thru the net.. but there isn't much stretch. I've also weaved them thru net during stretch when I knew it was going too.

if you want a giant tree and move your cobs up while it grows and end up with the light at the top... with average stretch I'm guessing flip it at 3- 4 feet.... your light should be at the top and plants I'm guessing will be around 5 - 6 foot ( strain dependant main factor.. stress elemental conditions etc side factors)

again welcome to the forum

[Grower]

I am a noob but what is light penetration? I mean I am not really sure it is only altered by the output power of the light source, I think the more the light sources are the better the coverage is and more penetration we have since light is coming from different angles

@Jolly happy 420th post lol

[Jolly Green Giant]

here's a simple explanation... it's basically a theory of how much light is still making thru the leaves down to the bottom of the plant..

you know how you get Larfy/tiny buds sites way below the canopy? if you have awesome light penetration those will turn into real bud 3 -4 feet away from the lighting.

that little bud is 46" away from my light!! with 2 feet of canopy and leaves above it. it probably won't get to fully smokable bud, but it's extract material

and thank you

[wardo]

welcome to the forum first off
( second.. this is post #420 for me )

I would say it depends on your style of growing and strain dependant...

I like to keep shorter plants that are trained to fill a space... I use a 5x5x7 tent, but use a 4x4 tray on the floor.. with a scrog net roughly 3' off the floor. with my light( diy hlg550 equivalent) roughly 18-20" above the scrog, I still have a little over 2' above the light. I have buds forming at pot level! ( roughly 40" from light down thru canopy) I flip mine after I weave them thru the net.. but there isn't much stretch. I've also weaved them thru net during stretch when I knew it was going too.

if you want a giant tree and move your cobs up while it grows and end up with the light at the top... with average stretch I'm guessing flip it at 3- 4 feet.... your light should be at the top and plants I'm guessing will be around 5 - 6 foot ( strain dependant main factor.. stress elemental conditions etc side factors)

again welcome to the forum

Thank you, great info, I'm sure I'll be back. So I can get good size scrog plants like my hps friends... Looks it's going to be fire og this first time, maybe dream queen

[wardo]

I am a noob but what is light penetration? I mean I am not really sure it is only altered by the output power of the light source, I think the more the light sources are the better the coverage is and more penetration we have since light is coming from different angles

@Jolly happy 420th post lol

Like how far through the canopy light will go... Yeah having light all around wouldn't hurt, probably fluorescents.

[Grower]

but how can I quantify if a light has better penetration than another?

[Jolly Green Giant]

I'm assuming technically you gotta use something like a par or lux meter... I just visually notice the difference between my old hps and my QB's.. I'm sure ill need a meter to tell between different qualities of LEDs.

[Grower]

Yea I assume a PAR meter is needed but that way we are measuring ppf or ppfd.
Q1. 1000w hps Vs 1000w LM561c, how can you say that the HPS has better light penetration if the led fixture has better PPFD?
Q2. if PPFD from a single source light is higher in the middle and decrease moving away from the centre, can't we say that more light sources give more "light penetration"?

Dunno

@Jolly congratulation mr. mod!