New Grower Help please diagnosing this yellowing

[dazedandconfuzed]

This looks EXACTLY like my issues, it is surely a pH problem or overwatering.

 

[Eyes on Fire]

That list is an awesome ,on the fly way of figuring stuff out.Write it down somewhere,I did.works excellent.You should post that as a PH how to sticky man LOL! or ya already have it somewhere?:Sharing One:

 

[turtle360]

You still have 35 to 40 days left, looks to me like a nutrient lock out due to PH.....If you check out the chart at 5.7 in soil you'v locked out all but the last 3....

Here's a formula for figuring out soil ph..I reccamend a PH meter even better would be a probe, the ph wizard is the best thing I'v added to my grow room...
Rough Calculation Guide:

Here's some good info on ph.....
If your runoff pH is higher than your starting pH, use this equation to determine your soil pH:*
Soil pH = Runoff pH + Difference

If your runoff pH is lower than your starting pH, us this equation:
Soil pH = Runoff pH - Difference.

For example, say your the starting pH of your solution before it goes in is 6.5 and the pH of your runoff is 7.0. The difference is +0.5, so using the above equation:
Soil pH = 7.0 + 0.5*
Soil pH = 7.5

If your starting pH is 6.5 and your runoff is 6.0, your difference is -0.5 and using the above equation:
Soil pH = 6.0 - 0.5
Soil pH = 5.5

her's some more good info on PH in general
PH - Potential Hydrogen - The Manual - Polled

Thing is, and at the risk of repeating myself.........I tried using this calculation on runoff one month ago. I got 5.8. I use soil and nutes and a General Hydroponics ph test kit so I conferred with a rep and a Gen Hydro rep and they both said the ph runoff is not a valuable number. Take it or leave it. I know zippo. That's why I post on the New Growers' Forum. I listen to you and I listen to them and I cross my fingers. Tuesday I also tested a soil sample mixed with some magic potion and water and shook it up and compared it to the color wheel. It most closely matched 6.5. I've gone 44 days with barely a symptom of nute deficiency. I'm wondering about that flush I did with Clearex 2 days ago.

 

[az2000]

they both said the ph runoff is not a valuable number.

When you poured 6.5 in and got 5.8 out, according to the formula: you have 5.1 soil. The only reason I can think not to trust it is that you apparently use a color-matching ph kit(?). But, with the problem you're having it sounds like the problem is in that direction.

If the nutrients are ph buffered, that could have helped hold the ph in an acceptable range (until now). I had a similar problem. GH Flora Series seemed to hide a problem I had for my first two grows. I switched nutes and assumed everything was fine (because it always had been). At about 55-60 days (of a strain I normally harvest at 100 days) I started to have the usual calmag deficiency. Tested my runoff and it indicated soil ph 5.0'ish. Coincidentally I had an Accurate 8 soil probe on the way, and it confirmed the problem (perhaps showing it to be in the 4s). I think it was Muddy who suggested that the buffered nature of GH Flora Series compensated for a problem that existed before. (Might have been the hydro store guy, or at least that guy confirmed the logic.).

I suggest you buy a ph meter. (<<link) That one is $8 US with free shipping. You wouldn't think it to be good at that price, but myself and others have found it to be reliable. (<<link).

You asked if flushing is supposed to be good for them. Not necessarily. It's a stress. If the ph problem was due to salt buildup, the stress would be worth the stress of leaving the salt there. Question: During the last 5 weeks, what amount of runoff did you get when watering? If it was 20% or more, that should have helped avoid salt build up. If you didn't provide enough water to get much runoff (each watering), it's possible the problem is salt and flushing helped.

If flushing helped it may take awhile to see improvement. If it's a ph problem not due to salt (as mine was) you'll need to do other things like dolomite lime and maybe even cautious use of hydrated lime. In the meantime, the best thing you can do is foliar feed. When I had my problem I kept my plant alive for 2-3 weeks via foliar feeding.

I did initially sprayed with the following in a pint spray bottle:
1/2 tsp Epsom salt
3/4 tsp AK Fish emulsion
3/4 tsp AK kelp
1 drop SuperThrive

Next day:
1/4 tsp Epsom
1/2 tsp AK Fish
1/2 tsp AK Kelp
1/8 tsp Grow More Sea Grow flower/bloom nute (nutrient I was/am feeding through soil at 1 tsp/gal).

Next day:
1/4 tsp Epsom
1/8 tsp GM SG bloom nute
1/2 tsp AK Kelp

Next day:
1/3 tsp Epsom
1/3 tsp GM SG bloom nute
1/2 tsp AK Kelp

I mixed things up a little, reduced percentages, to allow for other things, etc. because I was shooting in the dark. I reproduce the details above just so you can get an idea of the range of strengths and mixes you can do.

Warnings:

1. I live in a dry environment and wasn't worried much about bud rot. The more humid your environment, the more cautious you want to be. Maybe use a fan to accelerate the drying. Maybe keep the don't drench the foliage. Maybe do it only once.

2. Protect the plant from strong light while the leaves are wet. They can burn.

3. You can use a "surfactant" or wetting agent to help the water spread and stick instead of bead and drop off. It's not required. I didn't use it. But, if you can obtain it, it helps.

The problem you face is that it will take awhile until you can water/feed again and check your runoff. If you still have a soil ph problem, you're going to have to foliar feed until it's corrected. And, you may have to take drastic steps to correct it. Hopefully it was a salt problem and you're already on the road to recovery. You have to weigh the risk of bud rot and decide whether to foliar feed while waiting to find out versus the risk that the problem isn't fixed and you're wasting valuable time. (An Accurate 8 soil probe helps in this regard. You don't have to wait to see runoff.).

If you continue to have a ph problem I can share with you what I did.

EDIT: I meant to say that my use of AK Fish was because, like you, I thought it might be an N deficiency. I was trying to cover all the bases. A bit of risk that the AK Fish will introduce a foul odor to your buds. I don't smell anything now, 3 weeks after using it. (I'm still 2 weeks from harvest. Just starting cleanse now.). But, wanted to warn you.

Some people foliar feed household ammonia for N. I've seen references to 1 cup (48 tsp) per 20 gallons water. That's 2.5 tsp / gal. I've not used this so I encourage you to do your own google searches and calculations.

 

[turtle360]

Key word, AZ, is stress. That's what flushing with an agent does. I didn't need to because my PPMs were low. I was feeding conservatively and there was no buildup or ph issue or anything else. The lesson is, let them be as much as humanly possible. Now in a way the plant is behaving normally for a maturing plant. Lower fan leaves yellowing, leaving energy for the flowers and top growth. So all is not lost. The harvest window may have been hastened and I need to keep an eye out. The dilemma as always is I've gotten 2 diametrically opposed suggestions. 1)The yellow's on account the nitrogen et al stripped, they're starving. Just feed them. The green will return. 2) They're 2 weeks from harvest anyway. Just keep flushing, plain water only. Let them finish.

This has been an interesting 45 days. First grow, after all. I have learned a great deal, thank you all. I never had any idea a final flush is a mechanism signalling the plant to prepare for end game. Very interesting.

 

[az2000]

I've gotten 2 diametrically opposed suggestions. 1)The yellow's on account the nitrogen et al stripped, they're starving. Just feed them. The green will return. 2) They're 2 weeks from harvest anyway. Just keep flushing, plain water only. Let them finish.

I re-read this thread and didn't see #2. GoAuto said they have 30-45 days left. I think you have considerable time left too. That's why I suggest foliar feeding as an alternate route of nutrition until the soil ph improves (which may require some liming).

I never had any idea a final flush is a mechanism signalling the plant to prepare for end game.

I don't believe the flush was "final," nor that it signaled much to the plant (that can't be unsignaled with more nutrients, but perhaps through foliage if the soil is as acidic as your runoff indicated.).

in a way the plant is behaving normally for a maturing plant. Lower fan leaves yellowing, leaving energy for the flowers and top growth.

You're right that this is what a mid- to late-flower plant does. But, I don't think you're there yet. And, there's still that runoff ph which indicates an acidic soil problem.

You're attitude is great, about this first grow being a learning experience. But, I think there's more to learn. You probably shouldn't have flushed (which you recognize), but that doesn't mean this is the end. A couple vendors have told you runoff isn't reliable, but experienced people here tell you it does. You're 45 days into a grow that should last about 90 days. If your soil ph is really off (as it appears to be), you can push her much further and learn a lot more. Don't give up.

I only have 8 months experience. What I've seen is that cannabis is finicky, but tenacious. If the slightest thing is off, it gives up. But, if it senses remedial activity -- it hangs in there and gives as much as you do.

If your soil ph is off as much as your runoff indicated, things will go downhill fast. It won't be that it got an "end of life" signal from the flush. If it really is a soil ph problem, you can learn a lot about foliar feeding and liming the soil. I think the plant will reward you for that effort.

 

[Muddy]

I agree that testing run off isn't the most accurate way to test your soil pH but unless you have a good soil probe like the Control Wizard Accurate 8, it's the best method available to a lot of growers. I've gone comparisons using my Accurate 8 vs. run off. Usually they aren't that far off, maybe a .2 or .3 difference. Also, those test strips are not the best. While they give you a general indication, they aren't anywhere near as accurate as a good digital pH tester. If you're feeding at 6.5 and getting run off near 5, you are most certainly in a nutrient lockout situation. If the Fox Farms soil you are using is Ocean Forest, it's known to have pH issues. Fox Farms exhausted their original material source about 2 years ago and since then have had quality control problems. We've seen bags of OF read as low as 4.5 right out of the bag. I suspect you may have gotten one of them.

I'm not a fan of flushing plants unless it's absolutely, positively necessary. In your case I don't think the flush was needed and would have advised against you doing so. Flushing stresses the plants and unless some mild nutrients are given in the last gallon of flush, it leaches all the nutrients out of the soil. Here's what I would suggest:

Add some dolomite lime to your pots at the rate of 1 tablespoon per gallon of soil mix. Don't expect to see immediate results. It will take about 10 days or more for the lime to become effective and the soil pH to rise.

Feed at a higher pH until the numbers start to come up. Feeding at a pH or 7 or 7.2 should help raise the run off numbers.

Invest in a good digital pH meter and if you have the funds, an Accurate 8 soil probe. There's no substitute for having accurate pH numbers.

 

[turtle360]

I agree that testing run off isn't the most accurate way to test your soil pH but unless you have a good soil probe like the Control Wizard Accurate 8, it's the best method available to a lot of growers. I've gone comparisons using my Accurate 8 vs. run off. Usually they aren't that far off, maybe a .2 or .3 difference. Also, those test strips are not the best. While they give you a general indication, they aren't anywhere near as accurate as a good digital pH tester. If you're feeding at 6.5 and getting run off near 5, you are most certainly in a nutrient lockout situation. If the Fox Farms soil you are using is Ocean Forest, it's known to have pH issues. Fox Farms exhausted their original material source about 2 years ago and since then have had quality control problems. We've seen bags of OF read as low as 4.5 right out of the bag. I suspect you may have gotten one of them.



I'm not a fan of flushing plants unless it's absolutely, positively necessary. In your case I don't think the flush was needed and would have advised against you doing so. Flushing stresses the plants and unless some mild nutrients are given in the last gallon of flush, it leaches all the nutrients out of the soil. Here's what I would suggest:

Add some dolomite lime to your pots at the rate of 1 tablespoon per gallon of soil mix. Don't expect to see immediate results. It will take about 10 days or more for the lime to become effective and the soil pH to rise.

Feed at a higher pH until the numbers start to come up. Feeding at a pH or 7 or 7.2 should help raise the run off numbers.

Invest in a good digital pH meter and if you have the funds, an Accurate 8 soil probe. There's no substitute for having accurate pH numbers.

And the administering of the dolomite lime, it's a matter of sprinkling it on top of the soil and watering it down?

- - - Updated - - -

Do you use this thing:
http://www.hydroponics.net/i/136610

or

http://www.greenerhydroponics.com/Accurate-pH-7-Soil-pH-Moisture-Meter_p_76697.html

Is it the fat thing or the skinny probe?

 

[Trapper]

I think the long, skinny Accurate 8 is the one that is desired and talked highly about (the one I have anyway) and the 7 doesn't have much press about it on the grow sites that I've seen.

 

[turtle360]

I think the long, skinny Accurate 8 is the one that is desired and talked highly about (the one I have anyway) and the 7 doesn't have much press about it on the grow sites that I've seen.

OK. I thought you had mentioned its wide girth so I was picturing the other one. I should probably pick one up......