Potential Mag deficiency?

Hi guys, got these somewhat "lighter" veined new growths in the last week or so.
I've been defoliating thoroughly cause this gal is very leafy, so i absolutely gotta catch this deficiency early to not blow it all, it's my only plant.




Temps are somewhat high, 30-32 °C max.
I'm growing Indoor in Soil, this is day 53.
Bagseed in 11L fabric pot.... i'm watering 3L every 2-3 days (20% runoff cause Biobizz bottled nutes but i'm being very light w/ nutes).
Should be in the middle of 2nd week of flowering.

What do you reckon?
Gotta beef up on TopMax and BioBloom?

Today is nutes day on my feeding schedule

Entusia said:

Hi guys, got these somewhat "lighter" veined new growths in the last week or so.
I've been defoliating thoroughly cause this gal is very leafy, so i absolutely gotta catch this deficiency early to not blow it all, it's my only plant.

View attachment 4956393
View attachment 4956394

Temps are somewhat high, 30-32 °C max.
I'm growing Indoor in Soil, this is day 53.
Bagseed in 11L fabric pot.... i'm watering 3L every 2-3 days (20% runoff cause Biobizz bottled nutes but i'm being very light w/ nutes).
Should be in the middle of 2nd week of flowering.

What do you reckon?
Gotta beef up on TopMax and BioBloom?

Today is nutes day on my feeding schedule

Click to expand...

Mg def. Very common with biobizz(peat based) soil. You need to up your pH.

Wastei said:

Mg def. Very common with biobizz(peat based) soil. You need to up your pH.

Click to expand...

Hi Wastei, thank you for being here.

Biobizz CalMag (and more) as well as Advanced Nutrients Rhino Skin are already on their way to help me and the plant deal with the heat and all possible deficiencies.

I want to be clear though: i'm not using Biobizz soil.
The soil i'm using is a 70/30 mix of Organic potting mix and Volcanic lapilli (little porous rocks).

The organic potting mix (by Tercomposti) is itself a mix of:
- Peat moss (Blonde and Dark)
- Coco coir
- Green composted soil conditioner (Organic composted amendments)

I use this potting mix as is for many plants in my garden and they love it, it has great pH buffering, water retention and root zone aeration capability, but it usually tends to be slightly acidic and also tends to easily becomes hydrophobic when underwatered.

Volcanic lapilli on the other hand are little (1-2-3cm big) slightly basic volcanic porous rocks, they make up about 30% of the Soil mix and help "neutralize" the soil pH, but also make up the 2-3cm "cover" and 3-4cm "bed" of the pot to help with drainage and avoid gnats/overwatering.

I always water at 6.0-6.2 pH and runoff is usually coming out at 6.6-6.8 pH so i don't think it's a pH problem, but i could be wrong!

Since this is the farthest i've ever taken a Cannabis plant i'm still very much a beginner grower, alas one that tries to study, rationalize and analyze every little detail.

Do you think what i said here makes any sense at all?

You have plain epsom salt? water in a little, youll know in few days if it was Mg.

A good tip I got from here is put a pinch of epsom and 4 drops of armor Si in a 500ml spray bottle.Spray your buds twice a week.
Youll thank me later.

Hi myke!
Thank you too for being here, i REALLY appreciate it when people take some time to help out poor newbies like me

Unfortunately i do not have "plain Epsom salt", or "Armor Si" for that matter. Since i'm not in a legal country i don't know where i would even be able to find it or what to ask for, except for the Cannabis Growshops which i avoid at all costs because i believe they're monitored by local law enforcement: a couple guys i knew that growed have been followed home and caught red handed after visiting one of these shops.

Also now i don't know anyone that grows, so unfortunately can't ask a friend to help out.

Do you reckon i could wait this deficiency out for a couple more days, until CalMag and Rhino Skin (rich in Silica, to help out with the heat) arrive?

Are those BioBIzz bottled nutes organic? If yes, no need to achieve 20-30% runoff.

Epsoms salts are widely used outside cannabis, they are used for baths and also in the beer industry, to name something. Also as a diet supplement.

Have you thought about top dressing with dry amendments? Sounds more in the line of using an organic soil from the start.
Do you have access to quality earth worm castings or compost? Super important if you want to go the organic way, check the Organics section of the forum when you can.

Your female you should have Epsom. It’s used in baths. Check your local pharmacy. It’s really cheap

myke said:

Your female you should have Epsom. It’s used in baths. Check your local pharmacy. It’s really cheap

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Hey now. Not just females can have a luxurious bath time…. I mix my epsom salt with essential oils, steamy hot water, blunt snd see ya in an hour. Lol.

Wastei said:

Mg def. Very common with biobizz(peat based) soil. You need to up your pH.

Click to expand...

I will 100% trust your experience on this one, i feel like i should act very fast because thorough defoliation leaves very little margin for error.
Since i should be watering today with nutes, i want to try something different, and what you advised sounds good enough for me since soil is not Biobizz, but is still peat-based nonetheless.

Everybody!
Do you guys think the pH adjusted at 6.5-6.7 will suffice for the time being?
Would be 0.5 points more than the usual, which is 6.0-6.2

Or do you think i need to water at even higher pH, like at 7.0-7.2 ?
The untreated water i get is around 8.0 pH and i have no clue what a good pH value would be in my case

JHake said:

Are those BioBIzz bottled nutes organic? If yes, no need to achieve 20-30% runoff.

Epsoms salts are widely used outside cannabis, they are used for baths and also in the beer industry, to name something. Also as a diet supplement.

Have you thought about top dressing with dry amendments? Sounds more in the line of using an organic soil from the start.
Do you have access to quality earth worm castings or compost? Super important if you want to go the organic way, check the Organics section of the forum when you can.

Click to expand...

Yes, Biobizz bottled nutes should be organic, but in my previous post someone told me to water to 20% runoff anyways, and i've been doing just that since the last couple of weeks. I've been using Rootjuice, BioGrow, BioBloom and TopMax.

Will defo check out the Organics forum, Organic cultivation always intrigued me.
Never thought about top dressing w/ dry amendments and don't really have access to quality earthworm castings or compost, but i never really looked around for those. Will look into them around here.

myke said:

Your female you should have Epsom. It’s used in baths. Check your local pharmacy. It’s really cheap

Click to expand...

I'm not female...... did you just assume MY GENDER?!? (jk lol, am not woke and no snowflake either)

Promise to find Epsom salts TODAY! This is my mission now!

Entusia said:

I will 100% trust your experience on this one, i feel like i should act very fast because thorough defoliation leaves very little margin for error.
Since i should be watering today with nutes, i want to try something different, and what you advised sounds good enough for me since soil is not Biobizz, but is still peat-based nonetheless.

Everybody!
Do you guys think the pH adjusted at 6.5-6.7 will suffice for the time being?
Would be 0.5 points more than the usual, which is 6.0-6.2

Or do you think i need to water at even higher pH, like at 7.0-7.2 ?
The untreated water i get is around 8.0 pH and i have no clue what a good pH value would be in my case


Yes, Biobizz bottled nutes should be organic, but in my previous post someone told me to water to 20% runoff anyways, and i've been doing just that since the last couple of weeks. I've been using Rootjuice, BioGrow, BioBloom and TopMax.

Will defo check out the Organics forum, Organic cultivation always intrigued me.
Never thought about top dressing w/ dry amendments and don't really have access to quality earthworm castings or compost, but i never really looked around for those. Will look into them around here.



I'm not female...... did you just assume MY GENDER?!? (jk lol, am not woke and no snowflake either)

Promise to find Epsom salts TODAY! This is my mission now!

Click to expand...

Haha,my bad your avatar pic I just assumed.Any of your female friends will help u with epsom salts just get plain non perfumed.

Id ph to6.5- 7 since youve been low for awhile.

A Mag deficiency would show up on the older, lower leaves. This looks like a micro deficiency or a PH imbalance.

LEDsnake said:

A Mag deficiency would show up on the older, lower leaves. This looks like a micro deficiency or a PH imbalance.

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Could this happen because of starting watering to 20% runoff for the last 10 days or so?

Until i started "flushing the soil" as recommended in another post i was using very little Biobizz Organic nutes and giving around 10% of the container volume in waterings, the plant was coming up fast and showed great vitality, bounced back very fast every time i binded her or defoliated.

Now it just seems a little bit slow, could very well be flowering phase but also the stretch has not been dramatical yet, maybe 1-2cm branch growth in the last week or so.

There shouldn't be any shortage of micro elements, and yes it could very well be a pH imbalance caused by watering to 6.0-6.2 since the start, but i always monitored water and i checked runoff as well a couple of times and everything pointed towards the soil being slightly basic.

Could the soil pH have changed suddenly or more gradually but now it's causing deficiencies?

myke said:

Id ph to6.5- 7 since youve been low for awhile.

Click to expand...

That's what i ultimately did guys:
I watered w/ 2L (no runoff) at around 6.7 - 6.8 pH with regular dose of Biogrow, Biobloom and Topmax.
Hopefully i can fully stop this deficiency quickly today with a foliar spray of Epsom salts + "Armor Si"-equivalent.

I also noticed that Biobloom and Topmax affected the water pH more than what i was used to, so i may have watered once (one time only) with a pH value that was slightly lower than 6.0 - 6.2. That one time could also be the cause of this Mg deficiency, but i'm rather skeptical of it.

Entusia said:

That's what i ultimately did guys:
I watered w/ 2L (no runoff) at around 6.7 - 6.8 pH with regular dose of Biogrow, Biobloom and Topmax.
Hopefully i can fully stop this deficiency quickly today with a foliar spray of Epsom salts + "Armor Si"-equivalent.

I also noticed that Biobloom and Topmax affected the water pH more than what i was used to, so i may have watered once (one time only) with a pH value that was slightly lower than 6.0 - 6.2. That one time could also be the cause of this Mg deficiency, but i'm rather skeptical of it.

Click to expand...

Other possibility is light too close and or they just need more food.Change 1 thing at a time and see,after a few grows you'll have less and less troubles.

myke said:

Other possibility is light too close and or they just need more food.Change 1 thing at a time and see,after a few grows you'll have less and less troubles.

Click to expand...

Let's see in a couple of days if changing only the pH stops the symptoms.
The "pH possible cause" is now called Cause 0) which i'm trying to solve and exclude from the list of candidates.

If the somewhat rapid leaf discoloration keeps progressing i think there could be only a couple other main causes (w/ potentially concurrent factors that further worsen the symptoms):
Cause 1) I'm not giving enough nutrients, which is causing macro/micro deficiencies that then cause leaf discoloration. I am actually giving a tiny bit less than the Biobizz feeding schedule recommends, as well as i'm not watering with ferts every time (as recommended) but only once a week. This could have more concurrent factors in:
Factor A) high temps (-> high VPD -> high transpiration and nutrients uptake -> fast soil depletion -> macro/micro deficiencies -> leaf discoloration)
Factor B) watering to 20% runoff even if organic (-> flushing nutrients and microlife -> fast soil depletion -> macro/micro deficiencies -> leaf discoloration)
Factor C) nutes are leftovers from my very first failed run a few years back (> 3/4 years ago) and do not work as intended. I read online that Biobizz nutes never really expire, instead they just lose some potency (around 10-15-20% after the 2 years mark) and since i've also been using them on other fruiting plants and ornamentals outdoors with very visible results, i *know* they're still working, but maybe they are not working hard enough for this plant/soil, so this could be a concurrent factor as well.

At this point i think this is the most probable cause of the leaf discoloration, considering all its serious concurrent factors, since it doesn't really look like one specific deficiency... it just looks like the plant can't sustain its leaves at all and they just slowly die off.

Cause 2) The light is too close and leaves are getting light damage, age rapidly, yellow out and dye. Unfortunately i can't do much about this, 12" is all the vertical space i have left. During the grow i've been saving all the space i could for when i would be needing it the most, which is now (the switch to flowering to compensate the stretch) by training with LST + topping + scrogging.

Could very well be that both Cause 1) and Cause 2) (and maybe even a touch of Cause 0) are all concurrently causing the symptoms.

If you have any advice as to how to proceed without losing my dearest and biggest girl yet please help

This is some photos of this plant during the previous weeks:

Day 24


Day 26


Day 30


Day 36


Day 39


Day 43


Day 49


Day 54 (starts showing the symptoms)

Further research tells me these might also be the symptoms of a Zinc deficiency -> link (growweedeasy.com)



"The most common reason growers will see a zinc deficiency is when the pH at the roots is too high. Zinc tends to get locked at higher pH levels and is better absorbed by the plant in a more acidic root environment."

So, not too low pH, but too high?

Also, if it can be useful, i further researched Volcanic lapilli and found some data about amendments' pH:
Dark peat = pH 4.0-5.5
Blonde peat = pH 3-3.5
Volcanic lapillus = pH 7.0-7.5
River sand = pH 7.5
Pumice = pH 6.5-7
Expanded clay (Hydroton) = pH 6-7
Perlite = pH 6.5-7.5
Zeolite = pH 7
Vermiculite = pH 9

Could the 3-4cm bottom bed of Volcanic lapilli be causing high pH at the roots?
The symptoms look very similar to my photos and are sligthyl more fitting than Magnesium deficiency (discoloration straight from top, instead of bottom leaves).

Also other examples found on that website (that i'm visiting very frequently... it's awesome imho) might suggest high pH to be the main cause of this type of leaf discoloration, and i even had something similar in my previous (failed) run when i wasn't adjusting the water pH and basically watered always with pH 8.0...

This the Growweedeasy.com example:
"In this case, the symptoms were caused by the pH being way too high."



This is somewhat similar to what my previous plant looked like at the start of flowering phase (got only 1.5g from this lol, at least it was very good smelling and tasting xD). Mind that i was also probably overwatering, as well as not giving enough ferts and having higher temps with lower RH %.





After a good tough dose of Biogrow and Biobloom (which also lower the pH) and moving them outdoors the deficiencies started regressing.
The soil wasn't the one i'm using now: it was a mix of peats,, some river sand and 10/15% perlite. I also had gnats, leafminers, leafhoppers and probably trips too when i moved them outdoors, but they still "recovered from being indoors" lol.




I'm just a beginner... honestly pinpointing the cause is becoming a little bit too difficult for me, especially with all of this conflicting and confusing information and causes and solutions to chase. Will try to follow all your advices one at a time and hopefully get rid of the discoloration for good.

Not familiar with your soil but most of us dont pH our water when using these organic soils.
This soil works well in your garden you mentioned.Do you feed them the same way?
You mentioned runoff feeds.