Organic & Synthetic Grows---- Magnesium/Iron Deficiency--- Or Too Much Potassium? A Journal

What you guys think? Magnesium and/or Iron deficiency is the common answer here when there’s yellowing happening with the green veins. And when I see this it’s always at the top leaves when it appears, not the first time with me. The first was when I was in flower using synthetic nutes, never really recovered from that grow. Now on this grow, where I’m experimenting with organic dry amendments (with FoxFarm Soil) 5 weeks into Veg… it comes up again. o.O I was under the impression that in organic grows, if you took care of the soil, the soil in turn would take care of the plant. Little confused right now. My dry amendments are (all natural) Earth Dust Base & Earth Dust Boost, some Organic Kelp Meal, and Organic Langbeinite.

I water just enough to keep the soil moist and read an article that if you overfeed Potassium, the plant can absorb more of that in place of the Magnesium, and I’m really wondering if that’s possible in organic grows.

Another angle, or theory of mine is the possibility I just didn’t add enough amendments. and or I somehow overwatered these ladies which is easy to do in potted soil grows. Lot to think about here.

What I’ve done so far to help with this (recently) is top amend with 2-3 cups of Earth Worm Castings and a dose/watering of the classic RealGrowers Recharge (ultra concentrated microbial superpack).

I don’t think it to be from any issues (light stress) coming from my LED lighting as they are at 60% and hovering above at about 20 inches from the ladies

My question is, ride what I’ve done so far to see what happens or is there something else I can add or do? Am I out in left field with my whole thought process here?


Check this out there is alot of deficiencies that look like that

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Another good reference:

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Thanks, I just ordered a soil pH pen to see what’s happening down under. Not really sure what it means if the pH is to low or to high… I think if the soils pH is to low… you should add some type of limestone to bring it back up… not sure what to do if the pH is too high…and what pH is considered to high in organics. :thinking:
I’m still going with the magnesium idea and currently spraying the leaves with a light epsom salt solution once a day now

I use General Hydro pH UP and pH Down.

Those are perfect for Hydroponic grows (soilless), not so good for Organic Soil Grows, as they will kill off beneficial bacteria that break down organic materials into food for the ladies. Hence the use of organic materials (Limestone for example) that raise or lower the pH are highly recommended.

I’m in soil, I use these. I supplement microbes. I see no indication of them dying off. Sorry I wasn’t able to help.

Good luck, and happy growing.


No worries, I was, am, not sure anymore, using a pH down myself. Just small cap of the stuff was enough to drop a 5 gallon bucket from 8.3 to 7pH. What I said in the above post is what I was told. Not to use any of it. So not sure anymore. On one hand I have, keep using it and juice up the killed off microbes with (Recharge and/or White Shark). On the other hand I have don’t use the pH adjusters and… that’s it. So I’m kinda experimenting not using any bottled pH adjusters at the moment to see what jives with the ladies, how they react without it right now. Thanks for the input.

For supplements, I use Recharge and Tribus. I do add them after I pH my nutrient mixture, so maybe that’s the deal? Here’s the results on day 42 of flower.


The first rule of how to grow is to learn to stay out of the plant’s way. Your job is to create and maintain the best possible environment. A plant will take advantage of a proper setup.

Ensure the fresh air is changed ~every minute so the plant has a steady supply of CO2. Plants take in – or ‘fix’ – carbon dioxide from the atmosphere during photosynthesis.

Take room and leaf temp, a humidity reading, and plug those numbers into a VPD calculator to understand where you are as far a transpiration is concerned.

Maintaining the vapor pressure differential (VPD) between the room and leaf for the plant’s stage of growth will allow it to open and close the stomata so it can transpire. Transpiration is the pump that allows the CO2-O2 gas exchange and moves nutrients and water throughout the plant. This pressure differential pump even allows the roots to absorb nutrients. Exceeding VPD tolerance can cause the pump to run too fast or shut it off. Either case can result in disease and/or mineral deficiencies.

After any VPD issues are resolved, then ensure your lights are set to proper daily light integral — DLI — to optimize photosynthesis. High intensity lights can be controlled so photosynthesis can create food and use the provided water and nutrients. Balance photosynthesis by providing the plant’s light requirements for the growth stage it’s in. The Photone app is a cheap and easy way to measure light with your phone. It will toggle between PPFD and DLI.

After adjusting lights recheck VPD (leaf, room, humidity). Find a balance between VPD (transpiration) and DLI (photosynthesis) by controlling the environment.

As the plant grows, adjust the environment balance based on the VPD and DLI requirements for the stage of growth the plant is in. This is a frequent task based on growth rate.

Then pH test a soil sample. Hanna has a great tutorial. If it’s 6.5 +/- .3 you should be good. Correct the pH if not.

Another consideration is water source. Does it contain chlorine or chloramine or any other contaminates? What is the pH? Don’t water until the pot feels like an empty jug of milk or the plant shows you signs it needs water. Taking light, temps, and humidity readings and making adjustments are far more frequent than feeding or watering because the plant is always growing.

When all else is balanced and taken into consideration, LED(s) seem to increase Calcium requirements.

Then look at your nutrients to ensure you are providing 3 primary, 3 secondary, and 7 trace minerals in your nutrition of choice. Yours sounds good. Follow the mfr feeding chart.


Love it! Nice touch with the ornaments. I’ll check that Tribus out thanks. Ladies look awesome :sunglasses: Good stuff.

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I’ll try that Photone app (almost forgot about that one!) and dial in the DLI… thank you! And VPD… thinking I’m good, 75 (degree average and 60% (average) humidity. The ladies in the garage tent are responding well to the Earth Worm Castings I dumped on them, tempted to add another cup or two to the problem childs. If they come out looking as good as what @Newt gots going …I’m gonna be a happy camper. :grin:

Not looking bad really. Looks to be a PH issue from the 2nd pic. I’m a coco grower and feed to run off, not a lot of help with a living soil recommendation. @MeEasy is very successful using a similar set up. :love_you_gesture:


It looks more like light stress mainly because I don’t see any on lower leaves. It can also be an imbalance of nutrients in the soil, this happened to me when I first started using Earth Dust because I kept adding a bunch of stuff that is already in E dust like you have done here, soil has to have a balance in order to work good that’s why you need to allow it to cook in the beginning so when you continually add new stuff to it the soil can’t be balanced and it harms the microbial life that must eat it to feed your plants


Makes sense, I was about to order some Azomite to add to the mix, thought, well let me see if Earth Dust has any in there already…and yup has it in there. If anybody can overfeed an organic soil…it’s me. *sigh


I’m suspecting pH too, so ordered a Bluelab soil pH pen to really get to the bottom of this. I came across one of Nukeheads videos and they seem to be able to check the pH of the soil using a MULTIMETER. No joke, Just for shits and giggles I gave it a shot, according tot their method, I’m at 6.8 pH. I’m gonna play with the multimeter again to be sure. Talk about BroScience…lol, this has to be one of them but the vid almost has me fully convinced it works. For organics, I really don’t know if 6.8pH is ok.Lot of googling today to be done. And hopeful that pen gets here soon.

It’s not necessarily overfeeding it’s throwing off the balance and especially with living soil where you would never flush (like in hydro or coco to reset the mixture) or even water to runoff it has to stay balanced. I had a really hard time when I started with dust adding this n that, but the less I do with it the better it seems to work it works as a water only. Of course you have to top dress for flower as the instructions say


I read Neem Meal was really good at keeping the Gnats away, that’s always an issue here, they’re every where 24/7. Used a tablespoon per pot as a top dressing 2 weeks ago along with 2 tablespoons of Langbeinite for that magnesium boost. Didn’t work with that magnesium obviously. :unamused: but the gnats are few and far in-between. I’m a believer with the Neem Meal.

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Add epsom salt

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And… the pH checks out, anywhere from 5.8pH to 6.3pH. Calibrated the soil tester before use and went at it. Now I’m thinking just to feed it some organic liquid fertilizer. I’ve already given it the Earth Worm castings with a good dosing of Recharge. Been 48 hours since that’s happened. The yellowing has stopped but the ladies are still a light green. Yea or Nay on the Neptune?