Spots on my cannabis plants

Knight007 · Jul 10, 2025

I need help, I’m a new grower about my 3rd grow now.
I noticed couple days ago a few spots on the leaves of my plants and it appears to be getting worse on the same plant and has also spread to another,
I’ve tried using AI diagnostic but it’s telling me a whole bunch of problems, low cal/mag, nitrogen, fungus infection etc, if anyone knows and could help that would be amazing, thanks in advance.

** Additional info I’m currently growing outdoor and using biobizz organic feed they are about 28 days in, I moved them from inside an incubator to outside last week and I reside in UK

Hossgrows · Jul 10, 2025

These comes to mind. Are u keeping them in pots, or in ground ( amended). That can change everything.

Randyy · Jul 10, 2025

What is PH value of your water?
Are you following the recommended feeding schedule from BioBizz?
What soil are you using?
How far into the grow did you start feeding nutrients?

Knight007 · Jul 10, 2025

Randyy said:
What is PH value of your water?
Are you following the recommended feeding schedule from BioBizz?
What soil are you using?
How far into the grow did you start feeding nutrients?

I’m not testing ph but I’m using high quality bottled water, yes following schedule and dose that biobizz recommend and soil is also bio bizz light mix, I started feeding around 2 weeks in but upped nutrients and transplanted last week

Knight007 · Jul 10, 2025

Hossgrows said:
These comes to mind. Are u keeping them in pots, or in ground ( amended). That can change everything.

Thank you dude, I have a feeling it could be cal as I’ve only just started feeding with it since Tuesday as I didn’t think I’d need it this early on, so it makes sense

Randyy · Jul 10, 2025

Knight007 said:
I’m not testing ph but I’m using high quality bottled water, yes following schedule and dose that biobizz recommend and soil is also bio bizz light mix, I started feeding around 2 weeks in but upped nutrients and transplanted last week

I would recommend that you get a ph meter and check your water. since the plant is so young and you've been feeding them according to the recommendation, I doubt that it's a deficiency caused by nutrients not being present. I think the nutrients are present, but the plant might not be able to absorb them if the ph is off.

As the image above shows, certain nutrients are only available to be absorbed by the plant at certain ph values.

I can't say for sure that this is the problem you are experiencing since we don't know what the ph of your water is, but thats my take on it.

RoadKillSkunkHunt · Jul 10, 2025

Randyy said:
I would recommend that you get a ph meter and check your water. since the plant is so young and you've been feeding them according to the recommendation, I doubt that it's a deficiency caused by nutrients not being present. I think the nutrients are present, but the plant might not be able to absorb them if the ph is off.

View attachment 2472757
As the image above shows, certain nutrients are only available to be absorbed by the plant at certain ph values.

I can't say for sure that this is the problem you are experiencing since we don't know what the ph of your water is, but thats my take on it.

follow @Randyy's advice. He's spot on. It's not likely calcium at its young age.

franklygrown · Jul 10, 2025

The bottled water is demineralized and typically on the alkaline side. If your ph is off it will effect nutrient availability. Hard water here, I just add epsom and ph balance, I'm good to go with whatever other nutrients are needed.

ArtfulCodger · Jul 10, 2025

You might check the undersides of the affected leaves with a magnifier, looking for bugs. Just to rule it out.

Hossgrows · Jul 10, 2025

I can attest to the bottled water. I was using spring water. Out of curiosity I checked it. It was 8+, totally off the chart. My well water isn't attached to a softener, straight from the ground...It's spot on.

Knight007 · Jul 11, 2025

Randyy said:
I would recommend that you get a ph meter and check your water. since the plant is so young and you've been feeding them according to the recommendation, I doubt that it's a deficiency caused by nutrients not being present. I think the nutrients are present, but the plant might not be able to absorb them if the ph is off.

View attachment 2472757
As the image above shows, certain nutrients are only available to be absorbed by the plant at certain ph values.

I can't say for sure that this is the problem you are experiencing since we don't know what the ph of your water is, but thats my take on it.

Thanks dude I will take this advice and get back to you as I am using bottled water could be throwing the ph off massively

Knight007 · Jul 11, 2025

franklygrown said:
The bottled water is demineralized and typically on the alkaline side. If your ph is off it will affect nutrient availability. Hard water here, I just add epsom and ph balance, I'm good to go with whatever other nutrients are needed.

Thank you, I will get a ph monitor and have a look

Knight007 · Jul 11, 2025

Randyy said:
I would recommend that you get a ph meter and check your water. since the plant is so young and you've been feeding them according to the recommendation, I doubt that it's a deficiency caused by nutrients not being present. I think the nutrients are present, but the plant might not be able to absorb them if the ph is off.

View attachment 2472757
As the image above shows, certain nutrients are only available to be absorbed by the plant at certain ph values.

I can't say for sure that this is the problem you are experiencing since we don't know what the ph of your water is, but thats my take on it.

Thank you very much for this dude, I just checked the water I was using 8.2 PH

FUCK!!! didn’t even think man, Jesus I’ll amend ph and see what happens over the next few days, thanks again

Knight007 · Jul 11, 2025

franklygrown said:
The bottled water is demineralized and typically on the alkaline side. If your ph is off it will affect nutrient availability. Hard water here, I just add epsom and ph balance, I'm good to go with whatever other nutrients are needed.

It looks like my ph is off as the bottled water I’m using is demineralised and also sitting at 8.2 so I think you are right, I’ll take you’re advice into consideration and start again, thanks dude

Knight007 · Jul 11, 2025

Thanks everyone that got back to me with you’re wisdom it’s greatly appreciated, seems to be what as suggested above about the ph levels, I was using a bottled water that sits at 8.0 and had been demineralised (rookie mistakes) just ordered ph corrected and a tester so I’ll get back in a few days with the updates, thanks again greatly appreciate

franklygrown · Jul 11, 2025

Knight007 said:
Thanks everyone that got back to me with you’re wisdom it’s greatly appreciated, seems to be what as suggested above about the ph levels, I was using a bottled water that sits at 8.0 and had been demineralised (rookie mistakes) just ordered ph corrected and a tester so I’ll get back in a few days with the updates, thanks again greatly appreciate

Easy mistake, this is only my first real grow. I've had a bag seed in a pot, it's a start, like a matchbox car to a car guy. I did that adhd deep dive and have had looming success in my first real grow. I took these ten minutes ago.

Randyy · Jul 11, 2025

Knight007 said:
Thank you very much for this dude, I just checked the water I was using 8.2 PH FUCK!!! didn’t even think man, Jesus I’ll amend ph and see what happens over the next few days, thanks again

You are welcome, I'm happy to help.

Good luck with your grow moving forward!

Knight007 · Jul 13, 2025

Okay so update couple days later, she now looks like this I checked the PH and realised it was at 7.2 so I need a flush with just pure water at 6.2 which is recommended, but now i seem to be having the same problems in the other plants that I have too any suggestions :/

franklygrown · Jul 13, 2025

Knight007 said:
Okay so update couple days later, she now looks like this I checked the PH and realised it was at 7.2 so I need a flush with just pure water at 6.2 which is recommended, but now i seem to be having the same problems in the other plants that I have too any suggestions :/

Looks like cal mag deficiency to me, try a pinch of Epsom salt.

Knight007 · Jul 13, 2025

franklygrown said:
Looks like cal mag deficiency to me, try a pinch of Epsom salt.

Seems like it is I had a friend come around and take a look who’s been doing it for years, turns out I was using a light mix and didn’t add enough cal/mag, thanks mate appreciate the feedback

Spots on my cannabis plants

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Spots on my cannabis plants

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