Hi everybody,
today morning I’ve noticed big, regular brown spots between veins on upper leaves on some flowers. They appear literally over night. Do you have any idea what could be the cause?
thanks for help
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First off, welcome @Diarmaid, your plants might have a calcium deficiency. The soil pH might be too low; you should test it. To counteract this, you could use a fertilizer high in calcium or some gypsum.
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Hi and thanks for your recommandation. Problem is that I’ve already give them CalMag during last feedings. pH is also quite good- 6.3 for the soil substrate. So maybe it should be something else or I should give little bit more calcium ?
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Looks more like a trace/micro deficiency . . . boron or moly possibly
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hm, but again, I’ve already give them Micromix from Bionova with last feedings. It contains all micronutrients.
So, question is what next, give more? Or try opposite because this could be signs of overfeeding? Truth is, that EC in water excess is 2.4, so it’s quite good for 3rd week of Flowering.
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You should always pay attention to the growth of new leaves. Old damaged leaves do not recover from their damage.
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It’s older leaves, but brown spots appeared after adding micronutrients and CalMag, not before.
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One should always pay attention to the growth of new leaves. Old damaged leaves no longer recover from their damage.
Did the spots appear on the bottom of the plant first, or on the top?
Its only on top, and also only at some of the flowers
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If it starts at the top, it’s a lockout. This means that the soil pH is not right and the plant cannot absorb nutrients. The pH should be measured and flushed accordingly. If it’s too low, flush with higher pH, and vice versa. After that, measure the pH again and restart with a little fertilizer.
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But PH is 6,3 measured in excess and 6,2 measured directly in substrate root zone. So I don’t see any reason to correct it.
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Hey greetings. PH 6.2 is already a bit low.
Keep in mind that the soil also buffers the PH somewhat.
Try giving PH 7.0 as nutrient solution/water and it should improve. These brown spots definitely indicate a PH problem, and as a result, the available nutrients can no longer be adequately absorbed.
Calcium deficiency manifests as pinpoint brown spots.
Such elongated spots often indicate a PH problem.
A bit of garden lime, for me it was 10 gr per 16 l of soil worked into the soil, and watering with PH 6.9 - 7.2 brought the plant back on track. Especially when fertilizing organically with microbes, the soil can buffer the PH by 0.5 to 1. Greetings from Pflanzenpaule
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Hi, thanks for your thoughts. The truth is that I’ve put some microbes in last two feedings. I didn’t use them before so I have no experience with it. I’ll try to watering only with higher PH and see what will happen.
Only one thing is little bit confusing. You said that PH 6.2 is little bit low. But all sources recommends PH between 6.0 - 6.5 for soil substrate. During my previous grows I had usually PH around 6.2 without any noticeable problem.
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Well, my fellow grower, that’s already the pH problem.
I’ve been cultivating for a while, and now it’s my first time with Bio Bizz and microbe addition.
I also came across the idea that with microbes, it’s better to keep the pH of water and nutrient solution a bit higher.
Try to aim for
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I used Biobizz with my first grows, but change it for Bionova because it was quite unstable. With Bionova I have less trouble and bigger harvest. Until now when I try to ad microbes. Strange thing is that only 3 from 8 flowers has reacted with these brown spots. But as we know every flower is individual.
Also I’m still not sure about my new Sanlight light. I’m using it second time, first time I’ve got perfect results but now I’ve noticed light burn at the end of vegetation, so I dimmed it and flowers recovered. Truth is that I use for iPhone for measuring PAR which is not so precise as dedicated PAR meters.
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Hey, I also cultivate in the larger tent with San Light, and have 2 of them.
They are indeed very good high-end lamps.
Good that you recognized the light stress. There are several factors that play a role.
Only healthy, strong ladies can handle the power.
pH problems weaken and make them susceptible.
Then there are brutally light-loving ladies, and some don’t need such high light intensities.
If you recognize light stress, go to 80% in flowering.
That’s still enough for good yields.
It takes some time to adjust to the needs of the plants.
I hardly measure and do it by feel with the lamps.
Vegetative growth: 40 - 50% dimmer and 50 cm distance. Over time, I go to 40 cm distance, and from flowering, then 35 cm distance and dimmer 80%, sometimes even 85% depending on the situation.
It’s also true that the more light, the more nutrients in the soil.
And then the plant has to keep up.
I don’t think much of the apps for measuring PPFD either.
To measure very precisely, you really need to use a
Bloomstar E PAR meter or something similar. But those are expensive.
I actually cultivate in Super Soil.
I’m not very satisfied with the Bio Bizz range.
It was a test run with small bottles. And also the only one.
I wish you continued fun cultivating. Regards, Paule
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Yes, to be precise, in soil the pH should be 6.0 - 7.0.
However, the closer to 6 and below, some nutrients do not get into the plant at all or not sufficiently, and likewise at 7 and above.
The optimal would be 6.3 - 6.8!
That worked for you so far, until the microbes were added.
And then you quickly go below pH 6. Because then the soil buffers more. Even already in the water.
Is the fertilizer you are currently using an organic or mineral fertilizer?
Greetings
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I use standard Bionova range for Soil. This is my 6th crop. First three with Bio Bizz, so now this is 3rd with Bionova, which seems easier to use and with higher yields. As substrate I use Bionova Bio Soilmix. I’m still learning and upgrading my equipment 
It’s little bit up and down. One crop is perfect, second one problematic. But it’s life to learn from mistakes.
And yes it’s definitely big fun, as said Ed Rosenthal - Smoking is not additive but growing it IS 
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That is really true.
Every grow is different, even with the same strains in the same substrate with the same fertilizer. It’s like us humans, every plant grows and looks different. One needs more care, the next one less. You simply learn something new every time. That’s what makes the whole thing so interesting and varied. Simply a beautiful hobby with certain advantages.
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@Diarmaid
Yes, you never stop learning, and cultivating is indeed more addictive than smoking. 
I’ve definitely done 20 cycles, and it’s a challenge every time.
As @herr-gruen already says, every plant is different; even three seeds of the same strain result in three different plants.
This is always clearly visible with hybrid plants.
I’m also constantly upgrading, and it seems this will never end either.
The ups and downs will probably always be there. It’s the same for me, and I think for many others too.
I wish you continued fun growing, and let me know if everything gets back on track. Greetings from Pflanzenpaule
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