Gavita 1700 learning curve(light burn) advice plz

[mcaveman]

Think I figured out what happened had the lights around 30” from canopy and it was to strong , I have 30 clones cooking if I need them . If these bounce back am I ok or is the damage done?

 

[PpmOver9000]

Think I figured out what happened had the lights around 30” from canopy and it was to strong , I have 30 clones cooking if I need them . If these bounce back am I ok or is the damage done?

Hello, same lights here. In my experience 30 inches was the perfect hanging height for plants at that stage so not sure if the light height alone is an issue. How is your environment?

 

[mcaveman]

Hello, same lights here. In my experience 30 inches was the perfect hanging height for plants at that stage so not sure if the light height alone is an issue. How is your environment?

Co2 1300, humidity was 50 and air temp was 74. Ive since changed to 60 rh and 78 temp.

 

[mcaveman]

Co2 1300, humidity was 50 and air temp was 74. Ive since changed to 60 rh and 78 temp. I dont think its nute burn because im not feeding them but calmag

 

[PpmOver9000]

My initial guess is that the RH was a tad low but specifically the temp was far too low for LEDs so the plant transpired too fast and the light may have damaged them (VPD too high for veg). First things I usually do when I have a problem like this is back the light off and increase the RH a bit, so sounds like a great start so far.

Just as reference with the same lights I run my room at 82F and I am not using CO2. Unlike HIDs, LED lights don't produce much ambient heat so the leaf temps are much cooler than you'de expect.

 

[SecretGardener]

I got light burn with a new high-end LED. Got a light meter to measure the light level at the plant tops. Zero issues on my second crop with the new light. There's an phone app that measures the LUX level too. Measuring the light the plants receive seams more accurate than relying on the height of the light.

 

[mcaveman]

I have a cheap lux meter . What kind of levels should I have for 8” plants ?

 

[mcaveman]

My lux level is 10000 now I believe it was a round 20000 before .

 

[Aqua Man]

Many thing affect a plants tolerance to light including genetics so there is no 1 right value but... as a guide.

Clones under 5k
Rooted clones and seedlings under 10k

18/6 Veg 15-45k starting at the lowest and slowly working up 3-5k every few days to a week based on plant response.

12/12 flower 40-65k again starting low and increasing.

Almost every environmental factor will impact this as well as nutrient availability and transport.

 

[Aqua Man]

From the ppl I have spoken with using gavita 1700e starting clones about 4ft and pretty much letting them grow into the light is a really basic way to ensure they don't get to much light.

For the first week or 2 you want to see nice flat leaves. Not V shaped but after that you want to push them so the top 2-3 sets of leaves have a very slight V shape and below are flat. If the plants start pointing the petiole straight up at the top its an indication the light is to much. After a few days of this you will start to see damage and they will stunt. Often times they can droop around the edges and you start to see burning or bleaching.

The slight V in the upper leaves indicates early lights stress and you can walk that line to ensure your pushing as hard as you can without causing stress to the point of damage and stunting.

Dialing in a grow over a few cycles with nutrients and environment you will find you can push them harder.

#1 rule with light imo... when you see an issue (any issue) the first thing you want to do is reduce the light intensity as this is what is driving the plant. So if you continue blasting them then the issue will only get worse faster.