Drdre said:

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Awesome! :woot:

Best room I have seen in a long time. Congrats Dr.

Capulator said:

Best room I have seen in a long time. Congrats Dr.

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Thanks cap



Anyone know why plants do this. This would be my second run into this at first I thought it was nitrogen toxicity but have ruled that out after I dropped my n lower on this round. Only thing I could think would be ph fluctuation dropping low from using ro water with no calcium. Any thoughts or suggestion please.
Thanks drdre

Drdre said:

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Royally killing it! Props bro.

I'm just a soil guy. And far from your level. But I see N toxicity. If that's what it is it effects yield by reducing flower size. Best of luck.
Your room is deluxe. Thanks for sharing.

Drdre said:

Thanks cap

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Anyone know why plants do this. This would be my second run into this at first I thought it was nitrogen toxicity but have ruled that out after I dropped my n lower on this round. Only thing I could think would be ph fluctuation dropping low from using ro water with no calcium. Any thoughts or suggestion please.
Thanks drdre

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My trees always did that. Usually the leaves above the lights. JK said they were bending down to get at the light, but I think it also has something to do with the air flow (direct fan air). It has no effect on flowering/final product. How is your humidity?

Humidity is 40% during day 60-65 at night. I'm pretty sure it's ph. I just found a study with marijuana and Mexican chiles with low ph causing these symptoms which end result it took a toll on yield. I can also tell my plant are slightly behind. At my old place I had calcium in my well water now I'm using ro water so ph constantly fluctuates. I'll see if buffering ro water with well water helps.

Found this article hope it might help others In future.


I’ve grown cannabis more or less continuously since the Summer of 2004. During that time I have learned a great deal about this crop and how to grow it successfully indoors.

One thing that I have learned is that there are virtually no reliable resources when it comes to diagnosing leaf and stem symptoms in container grown cannabis plants. I have come to believe that most of the leaf and stem symptoms we encounter in this crop indoors are caused by soil pH that is out of range.

The two leading causes of pH problems are source water and ones choice of fertilizers. Both of these problems can readily be solved with some investigation and a well founded fertilization plan.

During a recent fertilizer trial I had the opportunity to observe the physical effects of very low soil pH on cannabis plants and to confirm the presence of those same symptoms in two additional plant species grown under nearly identical conditions.

A small group of cannabis plants were fertilized using a high potential acidity fertilizer. At 60 days the soil pH ranged from 5.68 down to 4.93. To varying degrees, all of the plants showed the following symptoms:

• necrotic or burnt leaf tips
• downward hooking and cupping of the leaves
• spots turning yellow progressing to ‘hole shot’
• purpling in petioles progressing to stems
• interrupted flowering

Here is a photo of a cannabis plant grown for the trial. The symptoms are quite visible.



The soil pH for this particular plant measured very low at 5.16. The hooking and cupping are clearly seen as well as the necrosis of the leaf tips.

Flowering in this plant had stalled almost completely and the foliage had a mottled appearance that was tending toward yellow. New leaves were pale and small.

Plants in this condition are compromised. They will finish flowering, but the yields and quality of the flowers will likely be diminished.

At the same time that I began this fertilizer trial I also started some New Mexico chiles and broad leaf sage plants from seed. I grew these in precisely the same media, fertilizers and water as the cannabis plants.

I thought it would be interesting and perhaps valuable to grow different species of plants alongside the cannabis, apply the same stress and see what could be learned. As it turned out there are very strong similarities in the leaf and stem symptoms I observed in all three species.

Here are some photos of a chile plant that was grown in the trial.



The soil pH in this plant measured 5.11 at 60 days. The most notable common symptoms were necrotic leaf tips, spots turning yellow progressing to ‘hole shot’ lesions.



The plants developed purpling in the stems and at the nodes above the fruit. This progressed downward to the main stem.



A moderate amount of downward cupping and hooking appear in the oldest leaves. The plant stopped blooming completely and the developing fruit was comparatively small for this variety.

Measures were taken to quickly raise the soil pH for these plants and the fertilizer was switched to a basic reaction type.

Within a week the chile plants began to develop new leaves and the overall color of the foliage improved dramatically. Soon after, the plants began to flower heavily and have since set well developed fruit.



As another comparison I chose broad leaf sage. Here are some photos of a sage plant grown for the trial.



The soil pH for this plant measured at 5.24. The most notable common symptoms were downward cupping and hooking of the leaves and purpling along the stems and at the nodes.



While each of these species is very different, I was able to observe very similar leaf symptoms when applying a common stress across the group.

This exercise has confirmed to me which leaf symptoms are most likely related to low soil pH in cannabis.

awesome thread. loving the dedication drdre. best wishes and keep up the love.

My 2 cents I have seen this too a bunch and nitrogen toxicity was the culprit, everytime... I cut back nutes and they went away but if they get to curled they might not fix themselves, also low light level will do this but I think it's to much nitrogen which causes that. By that pic I can tell they are to full. Every leaf looks real dark.

@Drdre that article is definitely a good read but it's also important to know that the grower doing the trial rarely fed any of his plants below 1.8 E.C. and his shit was almost always nitrogen toxic from using a cal-nit based fertilizer from scotts. We ran a room on his regimen and i've never seen plants look so bad in a large space...I can deal with deficiencies and Ph problems but the shit he deals with are all nitrogen and overfeeding problems which are definitely amplified with a lower Ph and pretty much impossible to make go away.

Those were some real low pH numbers for soil also.JK

Capulator said:

My trees always did that. Usually the leaves above the lights. JK said they were bending down to get at the light, but I think it also has something to do with the air flow (direct fan air). It has no effect on flowering/final product. How is your humidity?

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I agree with Cap….does this plant have direct air blowing on it? I've seen this happen on plants that had air blowing directly on it.

Flower pics

Pic 1 mango
Pic 2 more mango
Pic 3 black rose x mango
Pic 4 white jones
Pic 5 Chemdog #4 x gsc (divine genetics)

nice update. every mango Ive ran gave major weight. keep up the love brother.

cannapits said:

nice update. every mango Ive ran gave major weight. keep up the love brother.

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Thanks bro ya love the mango for that reason.

the camera phone just wasn't cutting it so here are some good pic

you can see my over feeding problem good thing it was caught early. thanks to all who reassured me on this.

That first pic is awesome man, can barely make out those cages.hell you can barely make out the individual plants, nice fuckin work doc!!!