P Deficiency?/quickest remedy?

[Hal]

OK...something is wrong with my girls, I'm pretty sure it is a P deficiency. For starters, I'm growing in organic dirt, one of the mixes from the organic dirt forum. Watering with RO water that has a PH of about 6. Initially thought it was N deficiency, due to yellowing leaves. I hit it with a fish emulsion tea to fix. Yellowing continued to spread, and I looked closer at the symptoms and changed my prognosis to P deficiency.

At this point I made a high P bat shit tea for the next watering. Didn't notice improvement, yellowing was still progressing a few days later. Decided to do a foliar feed with Pure Blend Pro (bloom formula for soil, 1-4-5), bottle recommended 2 tsp per gallon, I made the solution 1/2 strength based on some reading I did here on foliar feeding. That was 2 nights ago...last night the yellowing still seemed to be spreading. I gave it another foliar feed tonight, this time at the full strength recommended on the bottle.

One weird thing is the difference in the 2 plants. They are clones from the same mom (JLP's Sour Diesel x OG Kush) and are planted from the same dirt mix. Yet one of the girls is yellowing much faster than the other.

OK...here are the nittygritty details, followed by a few photos:

using soil...organic...a mix from the organic dirt forum.

problem started about 2 weeks ago.

the strain is JLP's Sour Diesel x OG Kush.

started from clone.

plants are about 8 weeks into the dirt.

plants have been in the current dirt for the last 6 weeks.

plants are being LST'd, height is unknown.

have been in flower almost 1 month, started 9-25-09

pot size: 14" L x 9" W x 3.5" deep (soil depth), 1 plant per pot.

organic dirt, with high N and P guanos and kelp for nutes. lime to balance.

I am watering almost exactly every 4 days. I am watering from the bottom, using RO water from Wholefoods that tests at about 6 PH.

I am growing in a small cabinet, with a mix of warm and cool CFL's, for the last month I have been able to go with about 169 watts due to the cooler weather.

I have a S&P fan pulling through a home made carbon scrubber with a passive intake through a dark room louver.

I have been on a 12/12 light schedule from before this problem started showing its ugly face.

Temps max out at around 85 degrees F, although there have been short periods where it got a few degrees higher before I was able to adjust the number of lights and reduce the temp.

I hope thats enough info. Here are the photos.

 

[Weedhound]

check your ph and make sure it stays in the normal range for whichever medium you are using.
Better yet transplant with fresh quality nuted soil......correct ph and feed at the same time. ALWAYS ph your water or nutes to correct ph to improve nutrient uptake unless yor simply giving ro or distilled PLAIN--no additves.

good luck

 

[VerdantGreen]

well if your dimensions are correct then you have these in less than a gallon of soil, and if they've been there for 6 weeks then i would say they are starving - they certainly look that way. i would feed them with guano tea or whatever - something faster acting like liquid seaweed would be good - dont try and make up for it by overfeeding though. you wont get the yellow leaves to go green but you should stop more from going that way. next time i would repot or add another couple of inches of soil in the bottom just before you flower them. pH shouldnt be a problem for you with 6 and dolomite in the mix (presuming you have that). i would also water from the top with the guano tea as that will act as a topdressing.

V.

 

[ibjamming]

It's perfectly natural for your large fan leave to turn yellow after a month of flowering. Keep doing what you were doing and in a couple of weeks you'll start your plain water flushing...then it's really going to look ugly.

 

[Hal]

Weedhound - I'm growing in organic dirt, the mix has dolomite lime added to it which takes care of PH balance, no matter what PH is of your additives are (within reason, of course).

Verdant - yeah, I think you are correct, I'm falling short on at least one nute, I looked at the symptoms and I feel it must be a phosphorous deficiency. Do you agree that it looks like a P deficiency? The amount of dirt I used was definitely on the short side, but its what I had ready to go, and I was lazy about mixing some more up, thought I would be OK with 3.5" instead of about 5" of dirt. Next time and thereafter I will be filling those containers up with dirt.

ibjam - I've never had my leaves turn this early, I can't help but worry that there is an important nutrient that's missing (hence the visual symptoms) that will negatively affect the amount of bud the plants are able to pack on. I don't want a miniscule harvest, if ya know what I mean.

 

[VerdantGreen]

it is natural but ime not desirable so early into flowering - perhaps at 6 - 8 weeks it is fine to leave it and you certainly want the leaves to fade by the end with organics.

V.

 

[VerdantGreen]

......

Verdant - yeah, I think you are correct, I'm falling short on at least one nute, I looked at the symptoms and I feel it must be a phosphorous deficiency. Do you agree that it looks like a P deficiency? The amount of dirt I used was definitely on the short side, but its what I had ready to go, and I was lazy about mixing some more up, thought I would be OK with 3.5" instead of about 5" of dirt. Next time and thereafter I will be filling those containers up with dirt.

....

i would say the brown patches are indeed P and the yellowing N but they look generally hungry. just dont overdo the feeding. from what i've read og kush can be quite picky.

V.

 

[Hal]

Since the problem initially appeared about 2-3 weeks ago, I have applied N with a tea made with fish emulsion, and P with a tea made with a high P bat guano. I think when you apply these things in a tea that they aren't immediately available to the plant (the microherd needs to do its thing and thats take a week or maybe a bit more), so I'm going to hold off on adding nutes for now. Maybe a foliar feed in a few days if the problem continues to spread.

Regarding the yellowing of the leaves...I checked out Stitches excellent thread describing all the various deficiencies and such, and the section on P def had some photos showing yellowing leaves. The difference in the yellowing between N and P is that the N def shows up with yellowing starting at the tips of the leaves and the P def shows the yellowing starting at the opposite end, near the leaf stem.