Undefined problem (cry for help)

Hello to everyone!
My cannabis is just 3 weeks old. About a week ago a problem occurred with my plant. At first, tops of the leaves became turning brown and then dried out. That necrosis slowly spread and the growth (as it seemed) slowed as well. I thought that my plant requires more fertilizers, as I was very careful about applying them.
After adding an organic fertilizer (proper solution), just in 3!!! days my plant resumed growth, but leaves become.. well you see.

Light: small 6400K bulb with reflector, according to my estimations plant receives up to 40 000 lm.
Fertilizer: organic, but no specifications on a bottle (unfortunately). I was VERY careful about it. And generally, I know many people to use it successfully.
Soil: neutral (6-7 ph)

1. Can anyone write what is wrong with my plant? It seems to me, that there is a lack of smth.
2. Is it possible to save my precious plant?
Would be grateful for any opinion.

P.S. Could the problem be with high water ph? In my region it varies from 6 to 8 (that disturbs me a lot).

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about all you can do is watch the new leaves...forget about the lower old leaves.

if the new growth looks ok?...it might make it.

Well, those second-level-old leaves started dying just 2 days ago....
Still, there is no so much of them to compare.

Whatever you're doing on nutrients... use less, start with 1/2 of what you're currently using. Assuming those are seedlings, they don't need much now and giving them too much will cause what you see vs. making them grow faster. Also, if you have a means of measuring nutrient strength and pH, you should. Knowing what you're putting on your plants is a good and will help you avoid this kind of issue in the future.

In fact I really share your opinion and by saying that I was really careful I mean that overdose is really unlikely.
I was using doses, that were more than two times less, than recommended for young plants (though there were no specifications, there was a clear and detailed instruction about fertilizer usage).
I do not really want to counter your words in any way, I just want to find out the real reason. Moreover, problems started before I decided to add more plant food.
Surfed web a lot and still no answer. Many sources relate this problem to a wrong ph, which disrupts proper nutrients absorption.
Growing is not so easy, after all :) Maybe someone experienced smth. similar?

P.S. Guess I will try to flush the plant with properly ph'ed water. Is it likely to survive? Recover?

No worries. Flushing is always good and won't hurt a plant. Just let it dry out a bit before giving it anything else.

Regarding your problems here, what are you using for soil?

Farmer Rich

Its just universal soil pack, bought in a common flower-selling store.
By the way, is it possible, that plant's roots begin to rot from excess of water? Though I've got drainage holes, I'm worried a bit.

Sounds like your soil may have nutrients in it, many from this source do and are wrong for weed. Plus you're adding a bit more fertilizer. In regard to the root rot question, possibly. You definitely want to let your plants dry out between watering. If these plants don't recover, you should chalk it up to learning and try again. On your next try, you should change to a neutral soilless mix for the grow medium.

Ph of water is about 7,5. Lowered it to ~ 6,6 - 6,7 (lemon acid) and flushed the plant with approx. 2 litres of water.
I was really impressed, that flushed liquid had ph about 7,5! That means that real soil ph level is up to 8!!!!
Damn...
Can I lower soil ph with permanent watering (provided I lower water ph to about 5,5?)

I don't know where you live, but go to an indoor grow shop and get soil they recommend, which will be something like Foxfarm's or Roots brand. Supernatural used to sell in these shops but I don't know if they still make a potting soil. I don't understand why you're being advised to flush as this will not solve your problem. You need better soil, not the flower store stuff you're using. While this stuff isn't bad, you have to add everything the plant need to survive, obviously, or you wouldn't be having this problem. It is a problem of nutrients, not water or root rot. Seldom will you see root rot unless there is alot of water and very high temperatures. You can continue using that soil if you want, but whether you get new soil or not, get a bottle of Dynagro 7-9-5 from an indoor grow/hydroponic shop and follow the directions on the back for a soil grow, 1/4 tsp to 1/2 tsp in a gallon of water, probably every time you water and in a couple weeks transplant to a bigger pot, preferably with foxfarm potting soil. Just don't water all the time, let the soil dry out some before you water again. It won't cause root rot to water, but roots need oxygen and the only way they get it in a soil grow is if you let the soil dry out between waterings.

I'm afraid I can't do that right now. My plant is only 3 weeks old and it still pretty small and fragile. I'll definitely apply your advice about changing soil, but right now I need a solution to prevent cannabis from dying before transplanting.
Any ideas? Maybe its better to leave it simply grow?

This is a very interesting thread for me right now because one of my mothers is doing this same thing! I am using fox farms forest soil, and the mother is about a year old, 3 gal bucket. For lighting I am just using x2 23w cfls with those hood brackets that focus the light. Sorry if I'm high jacking the thread, just thought I'd share my same frustration. The thing is I'm using good soil and I always correct the pH. Being old soil, I have been adding fox farms nutrients (grow big and the other veg nute). The only thing I can say is maybe the temps get low at night as its in a room by itself where the heat may not get to. Maybe lower 60's... But defiently not any lower. I do walk by the plant often though but how is this different from a fan blowing on it?

What I did do recently... I took the mother out of her pot, used my fingers to break apart the soil on the bottom 25%, and repotted in the same 3gal pot with fresh soil. Things haven't changed and the problem started before this. It's my GDP strain so I really dont wanna lose it. Anyways I'm sorry again if this is a hijack, but I was also thinking this might spark some ideas for others to go "oh yeah maybe thats our problem."

But back to your problem at hand. So you are only using 1 23w bulb correct? These things don't put out much heat but if too close it will burn the leaves. Maybe try to pull your light away a bit and go with x2 23w bulbs. One of these will not be enough for much longer anyways. I would agree with your soil being inadequate, because like others have said, it isn't for weed. I find that MG soil (miracle grow), binds up and doesn't absorb water very well (could be my problem), but when I switched to fox farms ocean forest soil, everything changed for the better. As for your pH problem, this is why I hydro now, lol! I think your pH problems are due directly to soil choice and with FFOF I never ran into this, but with MG I did every time. How to fix this... You can try lower pH and flush the water through, but it is a ***** to lower overall soil pH. The last thing I will add is if and WHEN you choose different soil, you can also go with a soil mix with very low to no added nutrients. I forget the name of the soil I'm thinking of, maybe Progrow or something, but what this allows you to do is monitor exactly how much nutrients your plants get. Of course you will need to feed often, but this is a more stable approach. Also, these soils I have mentioned have good buffers, which keep your pH from changing drastically up or down. A friend of mine uses this Prosoil, and never checks his pH, even with adding nutes as often as needed. I've seen his results, and this is a true testiment to how well these buffers work. Anyways, hope I helped in some way..

Quote:

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Originally Posted by Senny

Ph of water is about 7,5. Lowered it to ~ 6,6 - 6,7 (lemon acid) and flushed the plant with approx. 2 litres of water.
I was really impressed, that flushed liquid had ph about 7,5! That means that real soil ph level is up to 8!!!!
Damn...
Can I lower soil ph with permanent watering (provided I lower water ph to about 5,5?)

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If these are accurate numbers, then you found your problem. 8.0 is when Nitrogen, Phosphorus, and Potassium will start to be be locked out from the plant. meaning it wont absorb these nutrients, which are essential. what do you mean by permanent watering? you should never keep your soil completely moist. the only exception to this rule is when they are just starting to sprout. I know polishpollack said that flushing will not help, but it may. but dont flush with acidic water. flush with properly ph'd water (right around 6.5) and continue to water with this, flushing whenever the soil's ph starts to rise.