Early signs of Magnesium deficiency?

[AK-47 Gold Arabesque]

Hello all,

I am a first time indoor grower and poster from Cape Town, and am three weeks into my first grow.  The two oldest of my plants (Critical Auto) just hit 21 days of age and are starting to exhibit some light discoloration between the veins. According to my research this is an early sign of Magnesium deficiency? I would appreciate any opinion or advice. 

As this is my first grow, I am following along with a YouTube channel (SeedToStoned), as a basic guide on how to feed autos, as formulating my own mix amounts and schedule was a bit overwhelming.  This is the guide I am following.  The man uses gallon measurements, but I just converted them.  Water is always pH balanced between 5.5 - 6.0

Week 1 - Just pH balanced water, plants were happy

Week 2 - Terra Aquatica Cal Mag 2 ml/gallon, Terra Aquatica Micro 2ml/gallon, Terra Aquatica Bloom 4ml/gallon. 

Week 3 - Same as above, but 3:3:6

 

After more research today I realized I never buffered my medium with Cal Mag. None of the YouTube videos I watched or reading I did mentioned it apparently. I feel that this could be the issue? (Idk if mister YouTube man buffered his medium, but his plants are fine). I also didn't realize ppm/EC was a factor I was supposed to monitor? So I'm going to get a ppm/EC pen as well.

 

For now, I just mixed 3ml Cal Mag into 3.75 litres of pH balanced water (no other nutes) and gave the two plants a heavy watering. I'm not sure if this is enough, or if I am stressing too much in the first place?

Should I buffer my medium now with a water and Cal Mag soil drench, and do the same to the other seedlings? (15 days old)

In your opinion, is it a bad idea to follow a YouTube feed guide, and should rather go by the measurements on the side of the nutrient bottles? 

 

More info below:

Seeds

Simba Seeds Critical Auto Fem x 2 (One misgermed, got a refund)

Simba Seeds Amnesia Haze Auto Fem x 3

"Fruit Salad" seed from my friend x 1 (To replace the misgerm and cause why not)

Gear

Light: Green Houston 250W Quantum Board (Dimmable) x 2

Airflow: Standard RAM Inline Fan and RAM Outline Fan with Carbon Filter. (Will add oscillating fan once plants get bigger.)

Pots: Garden HighPro Larger Propots - 20lt x 6

Medium: Freedom Farms Coco-Perlite Growing Medium 70/30 

Environment

Light Cycle: 24 Hours, at 30% strength Week 1-2, 40% strength start of week 3 (built up in slow increments)

Temperature: 22-24°C

Relative Humidity: 50-55% (Airflow is doing a decent job, I turn on a small dehumidifier if it gets too high).

 

 

Edited June 1, 2023 by AK-47 Gold Arabesque
Grammar

[Prom]

As you gave em CalMag.. no way they have a Mag deficiency (if handled correctly).

Plants look good.. and you always check the new growth.. the old fan leaves can discolor and will never change back to normal, damage stays.

A bloom fertilizer in week 2 is a bit early.. but also not really damaging either. Same to the pots, 20L for autos is a bit big.. but works too, i prefer 10L pots.

You run 24/7 light cycle because of load shedding or you run 24/7 with backup?

 That sentence bugs me: For now, I just mixed 3ml Cal Mag into 3.75 litres of pH balanced water (no other nutes) and gave the two plants a heavy watering.

You pH the solution AFTER you put your fertilizers in... the solution you feed your plants need to be in the right pH range.. not the water you use.

 

You over care... look that your plants get the needed wet/dry cycles and stick to the fertilizer manual. They need magnesium for the chlorophyll, but also not in huge amounts. A CalMag feeding a month should handle the need... if you run the wrong pH in the solution, the plants can't absorb the Mg.. and you will run into issues even if you feed em daily. I recommend to let the solution you mixed and put the pH in the right area to stand over night and do a second pH test before feeding. If the solution is still in the right range, you are good to go, if not, adjust it again. Is critical that the plants get the right pH or things go very fast very bad. 

 

Just google: Coco choir pH range for Cannabis

You should end with a picture showing you all nutrients the plant needs and in what pH range it can get absorbed. I have Soil charts... not helping you or I would have posted. 

[AK-47 Gold Arabesque]

1 hour ago, Prom said:

As you gave em CalMag.. no way they have a Mag deficiency (if handled correctly).

Plants look good.. and you always check the new growth.. the old fan leaves can discolor and will never change back to normal, damage stays.

A bloom fertilizer in week 2 is a bit early.. but also not really damaging either. Same to the pots, 20L for autos is a bit big.. but works too, i prefer 10L pots.

You run 24/7 light cycle because of load shedding or you run 24/7 with backup?

 That sentence bugs me: For now, I just mixed 3ml Cal Mag into 3.75 litres of pH balanced water (no other nutes) and gave the two plants a heavy watering.

You pH the solution AFTER you put your fertilizers in... the solution you feed your plants need to be in the right pH range.. not the water you use.

 

You over care... look that your plants get the needed wet/dry cycles and stick to the fertilizer manual. They need magnesium for the chlorophyll, but also not in huge amounts. A CalMag feeding a month should handle the need... if you run the wrong pH in the solution, the plants can't absorb the Mg.. and you will run into issues even if you feed em daily. I recommend to let the solution you mixed and put the pH in the right area to stand over night and do a second pH test before feeding. If the solution is still in the right range, you are good to go, if not, adjust it again. Is critical that the plants get the right pH or things go very fast very bad. 

 

Just google: Coco choir pH range for Cannabis

You should end with a picture showing you all nutrients the plant needs and in what pH range it can get absorbed. I have Soil charts... not helping you or I would have posted. 

Thank you for the response! 

To answer your questions, I run 24/7 due to load shedding, all in all it ends up more of a 18/6 cycle with all the times the power is off. 

I do pH test as the last step, after I do all my nutrients. Typo sorry  . pH is always in the range of 5.5 - 6.0. 

For feeding, I usually feed every 3 or so days, which is how long it takes for the medium to become what I consider dry enough to water again.

I will do what you suggested and leave the solution over night to see if the pH changes.

Photo is how the biggest culprit is looking today.

Edited May 22, 2023 by AK-47 Gold Arabesque

[Prom]

I wouldn't say you have an issue... the fish bone pattern you most likely diagnose Mg deficiency on... doesn't match with the green. Mg deficiency always also yellows out the leaves (bottom). New leaves look good... and after the last response.. no complains how you handle things. If you have the same readings the next day as the day before, you can skip the over night wait, you do all correct the first time. PH can fuck you over super quick... why, as a beginner, giving you a second read before you feed.. can prevent surprises. The moment I pH huge containers, 150L area, i always suggest and do a over night wait, just to be sure it fits, will feed a lot of plants.

Autos are perfect for Eskom fuckups.. the more light the more potent, but they will finish with a good result. Lift the pot to be sure they need feeding. You can feel very easy if the pot is wet or dry.   

Edited May 22, 2023 by Prom
typo

[Prom]

Just watched the Video... ^^ had Autos going over 2m. So no, autos don't stay small by default 

Would be easier if a Coco dude helps you with the fertilizer, I am no big help and I would do more or less everything different as he did in the video  Just the mini cup plant he had was just not how you handle Autos.

The amount of CalMag he uses blew me a bit away.. thank good you can't really over feed those, the plant takes what it needs, the rest goes with the wash out if concentration is oversaturated. You need that much in Coco?? Anybody can help me out?

[AK-47 Gold Arabesque]

As I mentioned in the original post, on the product detail page for the Terra Aquatica Calcium Magnesium Supplement it says "When growing in Coconut Coir, using prepared soil or soilless mixes, or expanding compressed coco, use 1 to 1.5 ml per liter to wet (to saturation) the media, and then add to nutrient solution at the same rate for the first two weeks. Continuous use may be helpful for fast growing annuals."

I did not do this , and SeedToStoned didn't mention this either, and he didn't encounter any issues. I feel this is more likely the root cause of my older girls having this discoloration on the bigger fan leaves. 

All my other seedlings are still fine, as these two were at that age.

I am considering preemptively increasing the Cal Mag in the feed of my other seedlings to address the issue before it starts. However, I don't want to overdo it if they are looking healthy now, and there is no guarantee these will encounter the same issue, as they are different strains. 

Will just monitor them all day by day, and see how the new leaves turn out. I didn't realize that old leaves will never return to normal if they discolor  So thank you for that! 

 

Edited May 22, 2023 by AK-47 Gold Arabesque
Grammar

[Weskush]

My take on your situation is possible bad genetics. Invest a little bit more into an established breeder that sells you seeds in sealed breeder packs. Plants look fine. Just give them some time. Peace

[Naughty.Psychonaut]

unbuffered coco lacks cation exchange sites which means all nutrients will have less of an effect. you'll reach a point where giving and giving means nothing, you'll end up with salt build up cause the plants roots can't acess the nutrients. shock treatment with calmag does not resolve this, plus a shock treatment of Ca/Mg where there are no cation exchange sites in an inert medium may cause root burn and nutrient lock out aswell.

best would be to scrap the synthetic stuff, you can't buffer that medium while there is a plant in it, take about a 3rd of the top of the coco medium off, get lekker worm castings and top the pots up with organic media and shift over. 

a lot of people start their plants in an inert medium then "build" ontop of that as they go. 

but wait, it's an auto.....? with autos it's always a "one more fiddle and I give you the finger" lol I've never tried an auto cause I feel my skill level isn't quite up there yet, to grow a nice auto you gotta be ontop of your game. minimal mistakes, minimal fiddling. Maybe ignore everything I said, do what you can with this one, but with the next batch I would suggest get yourself some photoperiods. that way you can also clone them and have a second, third, fourth, fith .... heck as many chances as you want. also, they allow you to make these mistakes and be forgiven, you can turn a photoperiod around right at the grave. and I would also suggest to move over to the organic side. salt growing is quickly becoming a thing of the past, not only cause it's been proven to not be as great as people claimed in the early 2000's and infact is a big contribution to killing the planet, if you wana know more about how terrible salts are check this out .... as a cannabis grower I just cannot turn a deaf ear to this, it's heart breaking, trying my best to spread the positivety

 

[DesignatedDave]

On 5/22/2023 at 12:54 AM, AK-47 Gold Arabesque said:

After more research today I realized I never buffered my medium with Cal Mag. None of the YouTube videos I watched or reading I did mentioned it apparently. I feel that this could be the issue? (Idk if mister YouTube man buffered his medium, but his plants are fine). I also didn't realize ppm/EC was a factor I was supposed to monitor? So I'm going to get a ppm/EC pen as well.

 

On 5/22/2023 at 12:54 AM, AK-47 Gold Arabesque said:

Gear

Light: Green Houston 250W Quantum Board (Dimmable) x 2

Airflow: Standard RAM Inline Fan and RAM Outline Fan with Carbon Filter. (Will add oscillating fan once plants get bigger.)

Pots: Garden HighPro Larger Propots - 20lt x 6

Medium: Freedom Farms Coco-Perlite Growing Medium 70/30 

 

Freedom Farms Coco-Perlite is already washed and buffered, you don't need to buffer it or worry about that, you bought the right stuff

However, when growing with Coco Coir, you need to remember that the coco, over time is going to be constantly be competing for magnesium with your plant, its just the nature of the medium and you just manage it with some calmag.

I like to give my plants in coco coir/perlite 1ml / 1L of Terra Aquatica Cal Mag once per week just to maintain the "buffer" of the coco coir.
If there is a bit of deficiency like you seeing, you could give Calmag twice a week at 1.5ml/1L for 2 weeks until you see the new growth is looking good.

However, looking at your pictures, I would have said that your nitrogen seems a bit low, what nutrients are you using and at what quantities?

 

 

Edited May 23, 2023 by DesignatedDave

[trichomechaser]

In my opinion, I agree it's an early magnesium deficiency. That interveinal chlorosis looks bang on the money. Remember that while magnesium can be absorbed at lower pH it's most available from pH 6.0 onwards. I'd suggest aiming towards a pH of 5.8 to 6.3. I've noticed some issues on my side in the past when playing too close to the 5.5 range when it comes to magnesium uptake. That said, you can bypass the root uptake by performing some Epsom Salt foliar sprays. 

When I see a mg deficiency pop up on my side, I like to start making sure the soil can provide it properly, but also then do a weekly Epsom foliar. This tends to correct issues a bit quicker.

The comment regarding genetics, I always support the idea of better genetics. But in cases like this, some of the more sought after genetics are actually more prone to issues like this, as some of the elites can be quite tricky plants and very magnesium hungry in many cases (I've found a lot of OGs tend to be picky about their mg)

PS: Nice profile name. CSGO enjoyer?

[AK-47 Gold Arabesque]

Thanks for all the feedback! After increasing my Cal Mag slightly, the newer fan leaves don't seem to be having the same discoloration. I also kept my pH closer to 6.0/6.1 , rather than 5.5-5.8.

Also see some little pistils coming along on the biggest girl.

 

Edited May 24, 2023 by AK-47 Gold Arabesque
Grammar

[AK-47 Gold Arabesque]

On 5/23/2023 at 4:14 PM, DesignatedDave said:

Freedom Farms Coco-Perlite is already washed and buffered, you don't need to buffer it or worry about that, you bought the right stuff

However, when growing with Coco Coir, you need to remember that the coco, over time is going to be constantly be competing for magnesium with your plant, its just the nature of the medium and you just manage it with some calmag.

I like to give my plants in coco coir/perlite 1ml / 1L of Terra Aquatica Cal Mag once per week just to maintain the "buffer" of the coco coir.
If there is a bit of deficiency like you seeing, you could give Calmag twice a week at 1.5ml/1L for 2 weeks until you see the new growth is looking good.

However, looking at your pictures, I would have said that your nitrogen seems a bit low, what nutrients are you using and at what quantities?

I did mix in some other coco peat that came in a block, as well as perlite I bought separately (Was just short of growing medium for all the pots.) I doubt that was buffered, so it more than likely contributed.

I go by gallon measurements instead of normal people measurements, as I'm following a US based guide. 

Currently its 3ml Cal Mag, 3ml Micro and 6ml Bloom per gallon (3.75litres). For my next grow however I think I'll follow the per litre instructions on the bottles (Whilst halving the recommending manufacturer values, as I'm told that is what one does for autos as they require less nutes)

[iGrowDagga]

Spray Epsom salt