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help identifying the problem...nute or light burn?

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hey guys, 


I previously posted about this grow of mine about a month back and got a great response, so thanks heaps for that!- https://cannabis.community.forums.ozstoners.com/topic/80334-first-time-grower-4-plants-and-2-different-issues-help-please/ 


I'm growing 2 x OG Kush autoflowers in soil (Canna Terra).

Currently in week 9.

Running a 24/0 light schedule (to keep temps stable). 

I'm feeding them the flora trio nutrient range at 1/2 of the 'growweedeasy' recommended strength. 



Are these burnt tips from overloading with nutrients, or from their proximity to the light?


I've checked PPM of the run off and it is sitting at about 650 for one and 800 for the other. PH is stable at 5.9 - 6.0.


I have a 450w Viparspectra LED (running both veg and bloom switches)....I've run out of vertical space unfortunately, so the plants are only about 20cm from the light. 


If it is light burn then I'm not sure how to fix it, as I cant increase the height of the lights.


Any suggestions would be great!!




PS - sorry about the orientation of the photos - is there a way to fix this?




Edited by jables
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I reckon light burn. I have the vipar 300s, start off 32 inches for Veg. When I did try to flower with them recommended was no less than 18 inches away and that's for the 300s, you have the 450 so I'm guessing they need to be further away than the 300s.

20cm is about 8 inches.

Can you bend them over a bit?



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thanks guys. yeah I could try bending them, but they are week 10 now, so the stems are pretty strong. 


I have tried to just switch it to the 'bloom' switch, instead of both of them. Maybe with less light it might not burn them so much?


Just to confirm its not nute burn - are my PPM's OK at around 650 and 800 for the runoff?

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I’m very confident on LED light burn. Not just because your light is way too close, but you would expect some clawing if it was being over nuted.


With that light? You want it at about 55-60cm ideally. Absolutely NO CLOSER THAN 45cm. It will burn the plant and degrade quality and yield.


I have only been a grower for a couple years, but I have done a lot of research online. And I mean a lot. For a start I have read every page on growweedeasy and that’s the tip of the iceberg. There are endless other forums and sites. The best thing I can recommend and grower is to never stop reading. Knowledge I power.

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Light burn ? ,,,I thought leds bleach not burn ?


Can't see any bleaching going on ..never had it myself ...top leaves seem an ok colour but burnt tips say it's nutes are too strong .


Lots of plants will show signs of overfeeding without clawing,,,so to look for clawing to determine if it's over fed will lead you up the wrong path.


I'd back off on the nutes as has been suggested ,,,,

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It doesn’t have to be hot to burn. Off memory, I’m pretty sure it’s 24 inches distance for that light, but you should read up on it yourself for that particular model. I have one that I’m using for Scrog growing and it gets great results at bout 20-22” from the highest cola.


Here is some info on light burn. (Yes LEDs can burn aswel as bleach) https://www.growweedeasy.com/led-grow-lights-burn-cannabis-buds


Als another thing to consider is root rot. It’s hard to see on my phone, but it appears there may be some tips and edges curling up? Do you let it dry before each water? At least an inch deep should be dry before watering.

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