Brown spots

[RobReefer]

Hi all you green finger enthusiasts. I'm hoping for a little bit of advice on my plant and what better place to ask than GWE. I am a bit of a novice so apologies in advance it is a minefield.

I am growing girl scout cookies autos from fastbud 420


pot size - 12l
soil - bio buzz lightmix with 3 weeks nutrient
light - solar extreme 500 California light work hanging at 40cm above plants
Tent - 1m x 1m x2m

1 plant has got Brown spots on the big fan leaves and turning very crispy the other 3 are showing no signs. I have researched this but can't find an answer. I am not feeding the plants any nutes at the minute as I'm only at 3 weeks so it ain't over feeding. I have included pics so any thoughts would be greatly appreciated.

thanks for your help
Robreefer

 

[CaptainWiese91]

What is your Ph in the water you give ?
and what is the soil Ph ?

are you feeding it Cal mag supplement?

 

[RobReefer]

Oh is 6.5 I checked the run off last water and that was 6.3. No not feeding calcium or magnesium supplement, should I ?

 

[Rwise]

The leaves say there is a root issue, could be PH but may be from a feeding.

 

[CaptainWiese91]

Rwise is right, it is a pH problem or a root issue. But if your PH is on spot, then maybe your roots isn’t comfortable.

As for the cal mag - cannabis plants eat a lot of cal and mag actually. So it would be good for the plant to give it some a long the road. And if everything is on spot - I think you have a cal or a mag deficiency.

 

[RobReefer]

Thanks guys if I'm running into root issues at 3 weeks am I in trouble 😉

 

[Rwise]

Maybe bring the water up to 7 and get the run off to about 6.5, what is the water source? Tap water has calmag in it (they dont call it that), RO water has nothing in it and may not be PH stable, well water needs tests.

 

[Rwise]

I am not up on biobiz soil, does it have PH buffers in it? If not I would add pelleted sulfur and dolomite lime to it. Your plant will use these to adjust the soil to what it wants, and the dolomite covers calmag.

 

[RobReefer]

I am using tap water so I'll give it somesulfur and dolomite. Not sure if it is buffered the guy in the shop said it was better than plagron . Thanks for taking the time to help guys much appreciated,

 

[Canuck147]

Once you get this figured out you might want to snip off a few leaves - the ones blocking bud sites underneath. Do that and you'll be surprised at how fast those side branches shoot up.

 

[RobReefer]

Thanks Canuck I will do that mate