Is this light stress?

[VincenzioVonHook]

2 x 120W quantum boards will be well over 500ppfd at the plants.
i never had plants taking that much in veg.

Really? 500umol is only 1/4 sunlight. My six day old seedlings are currently getting 700umol and are fine. 500umol for 18 hours barely hits a DLI of 30. Do you usually run 20 or 24hr veg?

Not having a dig, just interested as numerous sources including Dr Bruce Bugbee have stated that marijuana is a high DLI plant, and does best with a DLI of 40-50 in veg, which is between 650-800umol over 18 hours.

 

[cobshopgrow]

yes really, just can speak for myself but its very reproducable, even in different media/fertilzer, near perfect VPD, temps and a very solid CO2 concentration always above ambient.
most often using 18/6 for veg.
am normally with bugbee too, but am more with chandra here who is saying cannabis plant tissue saturates at 700ppfd (at ambient CO2).
sure, cannabis needs quite some light tp produce fat buds, but its not a C4 plant.
going easy with the light always did the trick for me in veg and growth is even better then when theyre not blasted with light and sagging allday.

what have you used to measure the ppfd?

 

[VincenzioVonHook]

yes really, just can speak for myself but its very reproducable, even in different media/fertilzer, near perfect VPD, temps and a very solid CO2 concentration always above ambient.
most often using 18/6 for veg.
am normally with bugbee too, but am more with chandra here who is saying cannabis plant tissue saturates at 700ppfd (at ambient CO2).
sure, cannabis needs quite some light tp produce fat buds, but its not a C4 plant.
going easy with the light always did the trick for me in veg and growth is even better then when theyre not blasted with light and sagging allday.

what have you used to measure the ppfd?

I rent an apogee from a local hydro store. I'm way to broke to afford one lol. I ran a GDP and blackberry gum in a 2x4 back around August with 360w worth of quantum board. They sat 10" away for six weeks, and that was well over 1500umol (that's dimmed down to 70%).

Electricity waste for sure, but even as autos they pulled close to half a pound each and ended up over 5 foot tall, and didn't have any issues with light stress.

If anything over 700umol causes issues with cell necrose, that means plants on a cloudy day should die, let alone a sunny day.

 

[Samwell Seed Well]

just looking first photo feed much higher ... that plants not small

1000ppm min, well not min but close

i feed my seedlings 1000ppm

 

[VincenzioVonHook]

These are all 14" away from a full pelt 120w QB, and only a few days old. Probably doesn't need it in any way, but they are fine. I've got a tomato plant just out of frame so I've been giving them a bit of light as I've heard tomatoes love sun.
I could possibly save a shit ton of elec if that's true. I might give it a try @cobshopgrow .

 

[Adi1989]

There's your answer.

 

[Bukvičák]

Those plants look like they about to kick the bucket braa! Cut them down and start over again, they won't recover from that.

Stupid advice all the way down

 

[go go kid]

light stress

 

[DrOgkush]

Stupid advice all the way down

That fool has made over a dozen accounts with exact same profile picture each time running thru the forum talking everyone there’re plants suck.

 

[Star Dog]

I noticed a few of @bangengums posts raised an eyebrow right enough, the above "they'll not recover" for example, eh wtf is he on?

 

[mudballs]

I noticed a few of @bangengums posts raised an eyebrow right enough, the above "they'll not recover" for example, eh wtf is he on?

Wires loose...who knows. I just want him to stop going after sunni

 

[cobshopgrow]

These are all 14" away from a full pelt 120w QB, and only a few days old. Probably doesn't need it in any way, but they are fine. I've got a tomato plant just out of frame so I've been giving them a bit of light as I've heard tomatoes love sun. View attachment 5037893
I could possibly save a shit ton of elec if that's true. I might give it a try @cobshopgrow .

they look great, if they can take it go for it.
i have never grewn autos, maybe there is something, if i would grow a auto i would likely also be a bit more stressed with the feeling i need to max her out in veg.
ymmv, but if youre after saving some electricity, there is a lot potential to do this in the first 2-3 weeks.

light stress manifests often in posture problems while in veg, in flower it differs and there you get the classic bleaching, at least thats what i watch out for beside other things, tiger stripes, unhealthy red stems etc.


i have no seedlings going atm, but thats all growing well under 18.8W older COB tech i also start my seedlings in this box.

 

[Star Dog]

These were under 4x T5 for 2 weeks then on Saturday I swapped the T5s for a mars sp150w @17".
They appear to be doing fine atm.

 

[Adi1989]

View attachment 5037908 light stress

Pics from today the buds are going a light yellow Ive dimmed the lights to see what happens,

these plants are directlyabove the humidifier though so maybe could be heat stress

 

[VincenzioVonHook]

they look great, if they can take it go for it.
i have never grewn autos, maybe there is something, if i would grow a auto i would likely also be a bit more stressed with the feeling i need to max her out in veg.
ymmv, but if youre after saving some electricity, there is a lot potential to do this in the first 2-3 weeks.

That was my main reason for the higher light intensity. I wanted to give them as much as they could to get as much as I could in the three or so weeks veg.

It seemed to work as last lot were close to outgrowing a 200cm tent at week five/six. This was after mass defol and multiple colas removed to free space. These two were in 2.5 gal pots. Any bigger and I would have been fucked.