Brown Spots & Yellowing of fan leaves @ 4 wks flower.

RT seems to have some good info on things but Ive got a link here that may help you out with watering needs if the situation may arise.
Healthy Choices Wellness Blog » Blog Archive » ph Levels in Bottled Water

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Originally Posted by greenthmb

That is what mine look like, but the brown spots are smaller and more circular... and the leaves have turned more yellow than yours. Now that I've tested the pH of the water I feed which is 6.6, and the run off, which is 5.0, I am really confused.. Something in the soil is massively lowering my pH..

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RT ......... did you see the pic I posted of the leaves on here? I dont have a test kit but I have done as much research as I could in the short amount of time ive had since this prob happened and calcium or Mg is what I had pretty much decided on also. I havent had a test kit to check the ph#'s and that kinda stuff, no $ so how would I go about straightening this out or even guess-timating on what mix to use to fix the calcium issue?

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Originally Posted by Rusty Trichome

I'm not. Tiz why I asked those specific questions. :thumbsup:
Soil probes are notoriously inaccurate, likely your soil is buffered fine, and if your ingoing (plain) water is 6.5ish, that's fine too.

Yellowing with brown starting at tips and progressing twords the petiole (leaf stem) is overwatering or a drainage issue.

Yellowing and dying-off of fans is either insufficient light or a natural aging of the maturing plant's fan leaves as the plant 'borrows' it's nutrients and such.

Yellowing with blotches is usually a calcium deficiency. In your case, this is the likely issue, as different plants have different calcium needs and tollerances. Add it to the water per instructions.
Old leaves are old news, so don't expect to see leaves miraculously recover. But the other parts of the plant should show improvement after a couple of applications.

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Rusty- Thank you so much for your help. So far, I agree that it is most likely a calcium deficiency. I've given it an initial dose of Cal-Mag, but how long do I continue giving it? I will keep everyone updated and I will get some more pics up.. Hopefully others can learn from this post!

Happy Growing :thumbsup:

I haven't used CalMag in years, (I use unsulphered molasses) but once a week per instructions is a good place to start.

Homework builds character and a strong knowledge base. Don't stop researching. :thumbsup:

Blankstairs: This is greenthumbs thread. But if you'd like to start your own thread, I'd feel more comfortable discussing your issues there. Thank you.

So after just one dose of Cal-Mag my girl is already improving!!! :D The leaves with the brown spots are no longer yellow, they are green! As RT said, old leaves are old news, so the brown spots are here to stay, but I am pretty sure my girl is on the road to recovery.

I now have a better understanding of Cal-Mag deficiency, and have seen it in person. So although my plant was stressed, I now know what the symptoms are. Everything happens for a reason, and this is certainly a learning experience. Also, as I am still somewhat of a newbie to indoor growing, and I now have a much better understanding of pH and nutrient lock up.

Thanks again for your help Rusty!! I will keep everyone updated so they can learn from my post! I will post some recovery pics in a couple days.

:thumbsup:

Let us know if anything changes. :thumbsup:

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Originally Posted by greenthmb

Well, I tested the pH of the soil again, and it's 7.0 on the dot. I also tested the water that I feed it, and it has a pH of 6.6. So both are a little high. I typically do not test the pH of the run off, but will start at the the next feeding. I have looked at the FF soil feed schedule, but only for feeding instructions.

If this were a pH problem, why would it be affecting only one plant? Does pH affect each strain differently? Also, what should I do to safely lower the pH?

In addition, should I go ahead and give the Cal-Mag?

Any and all help is much appreciated. Thank you.

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i recomend cal magic by general hydroponics its the only organic cal mag available. use with every feeding at half strength. I would also recomend useing thrive alive micro nutes also at half strength with your normal feedings. Techna flora is the only organic brand of that. It's expensive but they give away there complete set of nutes, and I mean everything. I think you might be able to get sample set online. I get a business card from there tent for a free sample set at a music festival every year in Michigan. They arent small samples either. but theres only 2 organic products in the whole set. but its worth it for free. I don't know if you care about organic or not either. I am having same problem with one of my plants also. Don't get it. I am not in flower yet though.

be careful when using bottled water see where it is being derived from. if it isnt put through reverse oasmosis it is the same water u get out your sink maybe even less purified. Plus its expensive most grocery stores and all walmarts have a reverse oasmosis filling staion for $.35 a gallon. that way you control whats in your water. It has a ppm of 128 and ph of 7. all water should be 7 ph not 5.5. After you add you nutes ph naturally drops perfectly to 6.5 if using organic nutes. you can almost judge the amount of nutes in your water by your ph. if you put too much nutes in your water your ph is going to be low.