Spreadning necrotic spots on upper and middle leafs, top leafs getting pale

Im growing an Afghan skunk plant in a 10 liter airpot. Its at ~4-5 weeks of bloom.
The soil im using is a peat based soil with some permelite and vermiculite.
The soil has a pH of ~5.8, and my tapwater has a pH of 7.5 +
The pH of the runoff water is low, probably closer to a 5.5
Im using a 400w hps.

Necrotic spots and leafs are turning up on the upper-to middle leafs of the plant.

I dont have pictures, but this picture posted by a fellow grower looks a lot like what i have
https://www.rollitup.org/attachment...003-week-5-flowering-plant-problem-image.jpeg

It seems leafs nearer to the light are getting more affected, but its not isolated to leafs nearer to the light. And its not the top leafs closest to the light.


I have now tried to flush the plant.

But the day after it just seemed to get worse.

What can i do?


Im suspecting calcium and maybe mg lockout because of low pH, but im not sure.


When should i start feeding it with bloom-nutes again?

Do i need calmag of some sort?

Is there a solution for the low pH if flushing does not work?
Should i re-plant in a better soil?

Please help. Im getting really worried for my girl!

You must always add dolomitic lime when using any peat product........peat is naturally acidic, as are fertilizer salts. That's hard to overcome, as you are finding out. Lime helps keep the pH up and adds calcium and mg to the mix. Flush well, maybe add a small bit of hydrated lime (fast acting, you only need a small bit- research amounts before using). Then start watering with dolomitic lime in all your waterings. This will help keep your pH up. The spots are most likely a calcium deficiency but add cal/mag since they interact with each other closely. This late in flowering, you crop will suffer in (health/yield/quality) but consider it a lesson we all go thru when learning to grow properly.

SSHZ said:

You must always add dolomitic lime when using any peat product........peat is naturally acidic, as are fertilizer salts. That's hard to overcome, as you are finding out. Lime helps keep the pH up and adds calcium and mg to the mix. Flush well, maybe add a small bit of hydrated lime (fast acting, you only need a small bit- research amounts before using). Then start watering with dolomitic lime in all your waterings. This will help keep your pH up. The spots are most likely a calcium deficiency but add cal/mag since they interact with each other closely. This late in flowering, you crop will suffer in (health/yield/quality) but consider it a lesson we all go thru when learning to grow properly.

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Thank you. Its my first grow, and i certainly will learn from this for the future.

I have tried researching how much dolomite to add. But i cant find any good info.

How can i add it to my 10 liter air-pot without replanting? Should i replant?

Maybe im just dumb and cant find what im looking for. But i have tried. Any ideas anyone?
Would appreciate any ideas!

You can take a tablespoon or two and spread it around the top of the plant. Then water it in and it will start doing it's thing. Since you are so close to finishing, I wouldn't transplant.

I add 4 cups of lime (powdered, not peletized) to each 3.8 cu ft. bale of pro-mix. I think that's about 1-2 tablespoons of lime per gallon of pot size. So, in a 3 gallon pot, you'd use 3-6 tablespoons of lime, mixed well! Lime takes some time to break down and do it's thing so be aware it's slow acting. 10 liter pots are around 2.5 gallon pot size I think.

SSHZ said:

You can take a tablespoon or two and spread it around the top of the plant. Then water it in and it will start doing it's thing. Since you are so close to finishing, I wouldn't transplant. I add 4 cups of lime (powdered, not granular) to each 3.8 cu ft. bale of pro-mix. I think that's about 1-2 tablespoons of lime per gallon of pot size. So, in a 3 gallon pot, you'd use 3-6 tablespoons of lime, mixed well! Lime takes some time to break down and do it's thing so be aware it's slow acting. 10 liter pots are around 2.5 gallon pot size I think.

Click to expand...

Thanks. Did something similar. Mixed a few spoons with a liter of water, and fed it. Guess its basically the same. Replanted the younger ones i had. Thanks for the help. Now i can just hope for the best.

Yes, that's fine too. You might want to do it again in 7-10 days. Good luck with them......