leaves turning yellow an some brown spots - what could be the problem?

[fusa91]

Strain - White Widow
# of Plants - 5
Grow Type - Soil
Grow Stage - Vegetative
Bucket Size - 5 Gallon
Lights - 400 Watt Sunmaster dual
Nutrients -
20140210_172154 - 420 Magazine Photo Gallery
Medium - potting soil+ coco+ perlite
PPM - 900
PH - 6.5
RH - 30% to 45%
Room Temperature -78 to 90

Problem: My leaves are curling up of the bigger plant and has some dark spots on them. Any ideas?
the others are recovering from a nitrogen deficency.

These ones are recovering from N def:

This one i think its a little nute burned:

This one is healthy:

watering: 4-5 days and at 15 days i use nutrients with the NPK: 5-1-5

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

If you're using "potting mix" instead of "soil, " it appears you may need to drop the root-zone ph. The spots are Mn deficit, appears at the heal of the leaf, on the oldest of leafs and advances toward the tip. Honestly, I'm not sure what the ph should be with a plants that's half "soil" (if that's the case), and half coco (considered hydo, basically?). If soil? Would one set the ph around 6.1/6.2 or if your grow is considered a hand fed hydroponic system, would one set the ph @ 5.8? What say you?

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

i've mixed the soil myself... and i added 25 L of potting soil bought from the flowershop and about 5 L of coco and 2 L of perlite.. so my guess is that its more like a soil than a coco

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

and Mn its a manganese def ? I think you wanted to say a Mg magnesium def, no ?

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

Easy on the ferts, no more than 25% of manufacturers recommended dosage on the larger plant phed to 6.5/6.8

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

and Mn its a manganese def ? I think you wanted to say a Mg magnesium def, no ?

No, Mn, as in Manganese, indicative of a root-zone ph that's too high or a lack thereof of said nutrient.

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

when i feed them i use half the dosage recomanded.. it says to use 10 ml i use only 5 ml, on each 3rd wattering.


should i use less nutes for the bigger one ? on every wattering or 1-2 wattering without ferts and then feed them ferts?

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

I would attempt to follow the feed, water, water schedule. I would suspect the smaller one's would need even less, say, 10 to 12.5%, but you'll have to be very careful with the small ones. I'm not sure if the soil has the available nutrients to supply the smaller plants with what they need. With soil, usually the plants don't need any nutrients for at least a month. And always check the first bit of water that runs through the bottom to check your plants health by checking the run-off ph, it's critical, as too many folks ignor the most obvious that they should do but don't... big mistake.

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

that's what i'm doing now sticking to the schedule, yesterday i watered them and as you say i check the ph of the water that ran out through the bottom and it was 6-7.

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

but the plants are the same age.. 7 weeks old except the plants in the last 2 photos - 5 weeks old

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

but the plants are the same age.. 7 weeks old except the plants in the last 2 photos - 5 weeks old

It doesn't matter about the age, it's the size that matters most. As the plants matures the ppms of the nutrient solution will increase as the plant grows and nutrient uptake increases. 900 ppm's is too much even for the first plant that pictured, you should cut it back to half that amount for now.

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

ok, that i will do, ty for the help

and for the Mn def what shall i do ? use a fert with Mn ?

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

ok, that i will do, ty for the help

and for the Mn def what shall i do ? use a fert with Mn ?

Yes, many times I notice folks that don't use nutrients that contain Mn, it's only needed in minuscule amounts, but needed nonetheless... 0.08% respectively is a good measure.

 

[Marzbadrock]

Re: leafs turning yellow an some brown spots.. what could be the problem?

You say your runoff is 6 to 7. Which is it because it really matters. If you water with pH of 7.0 and your runoff is 6.0 then your soil pH is 5.0.

 

[Teldren]

Re: leafs turning yellow an some brown spots.. what could be the problem?

Spots almost look like when I got my guano tea on my leaf and didn't wash it off.

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?

You say your runoff is 6 to 7. Which is it because it really matters. If you water with pH of 7.0 and your runoff is 6.0 then your soil pH is 5.0.

the soil after watering has 7 ph, that's what i got now, i should lower it down a little.
.

 

[budstud]

Re: leafs turning yellow an some brown spots.. what could be the problem?

You say your runoff is 6 to 7. Which is it because it really matters. If you water with pH of 7.0 and your runoff is 6.0 then your soil pH is 5.0.

https://boards.cannabis.com/attachm...sted-leaves-some-tips-curled-down-phchart.jpg

 

[fusa91]

Re: leafs turning yellow an some brown spots.. what could be the problem?