Magnesium Deficiency?

Discussion in 'Growing Organic Marijuana' started by MGB, Aug 1, 2011.

  1. #1 MGB, Aug 1, 2011
    Last edited by a moderator: Aug 1, 2011
    I have been researching this problem for about a week all symptoms point to a magnesium deficiency. I am just looking for someone to back up my diagnosis.

    As you can see my oldest leaves from bottom to top are turning yellow, and the whole plant is turning a light green. I know it is not a nitrogen deficiency. I have given more than enough nitrogen to these plants. Unless somehow I have managed to lockout nitrogen.

    If it is in fact a Magnesium deficiency how do I find out if it is an actual deficiency or lockout.
    I ask this question because through my research I learned that to much Calcium can lockout Magnesium.

    I called the manufacturer of the organic liquid nutrients I am using. They blame it on my soil. I am using Premier Promix BX with Mycorise. They say their organic nutrients line prefers actual soil and not the medium I am growing in. I only wish that when I researched their product they had stated what type of soil was best for their nutrients.

    I then did some research on soils and found something about CEC's. Please excuse my ignorance but when they started talking about negative and positively charged nutrients I got totally lost. The article was way and above over my head.

    Now some questions on fixing the problem. Through my research I have found that by putting 1 tsp of epsom salts per gallon of H2O I can remedy this problem.

    Questions about epsom salt remedy.

    1) Are epsom salts organic?
    2) Are all epsom salts created equally?
    3} After using epsom salts will my 5 gal containers have a high salt content that will create more problems?
    4) If I use this remedy how long should I expect it to take before I notice the dark green to come back in my plants?
    5) Is there another remedy that would work better,faster. Please keep in mind I live in the middle of the woods and it is a 4 hour round trip to any nursery,grow shop etc. I have epsom salts on hand.
    6) When and if I use this remedy should I add this solution until I get 20% run off like I do with regular waterings and feedings?

    If you disagree with my diagnosis please back it up with fact. I am not one to do something w/o having fact to back it up. I am going to try to include some pictures if the sight lets me . I may have to many posted already.

    Thank you all in advance for any educated answers.If you have any questions on my soil,soil amendments, or nutrients refer to the URL in my signature.


    View attachment 661465
  2. MGB

    The folks at Premier Horticulture gave you sound advice. Products like ProMix (whatever flavor) or Sunshine Mix (whatever flavor) are not soils. You cannot grow a plant in them to any degree without doing something else.

    That something else is going to have to be adding a form of humus which is usually thermal compost and/or earthworm castings. If you're not going to use organic processes then you have to start using some form of chemical fertilizer salts.

    Epsom salts (Magnesium Sulfate) is a specific compound - MgSO4 meaning that epsom salts are epsom salts are epsom salts.

    You might want to consider sulfate of potash magnesia (sold using the term Sul-Po-Mag) which is basically (kind of, sort of, in a way) epsom salts with Potassium/Potash.

    I'm curious about this part of your post: I ask this question because through my research I learned that to much Calcium can lockout Magnesium

    Can you explain what you mean by that or rather what the author was explaining - I'm baffled. Particularly as it relates to CeC and I'm assuming that the author was talking about elemental Calcium (Ca++) and not a Calcium compound, correct?

    Just curious...........


  3. MGB

    See if this explanation makes sense to you......

    At it's very basic explanation soil is made up of only 2 components - rotted animal or plant material and shattered rock. Period.

    Anything else is an amendment - rocks, sticks, unrolled dead animals, raw manure, et al. Those amendments will eventually become part of the soil through microbial activity. Humus is where you get humic and fulvic acids and these carry a negative charge (-) and clay platelets also carry a negative charge. This is the basis of soil nutrient exchange.

    Most gardeners have a belief that all 'notes' are both absorbed and adsorbed in the same process. That is not the case and in particular the specific elements : Calcium, Magnesium, Phosphorus & Potassium and these primary elements that carry a positive charge (+) as do the overwhelming majority of the 73 macro and micro nutrients necessary for plant growth and health.

    Meaning that as elements are broken from their molecular bonds they are attached to the humus in the soil and are held in place preventing them from being removed by watering (flushing if you want to use that term). So you have this jigsaw of these specific elements being held tight through electrical charge in addition to the bacteria slime and the general structure of the root zone (rhizosphere).

    The plant releases a number of compounds in the form of exudes through the root hairs. One of those exudes is Hydrogen (H+) and Hydrogen is a form of exchange for the cations held in place by the humus. So the root exchanges its Hydrogen ion and takes a Calcium ion (or whatever) which is then moved into the plant's vascular system.

    IOW, the addition of Calcium to a soil to fix something does not result in a chemical reaction like mixing an acid with an alkaline. There is a 'reaction' but it's a process effected by microbes, plant exudes and electrical charges.

    Mixing a tablespoon of dolomite lime in a jug of water and applying to the soil and then checking 'run off' is some of the best comedy to be found anywhere on the web.

  4. LD

    First of all thank you for your reply. To be honest I am surprised you replied. I know how much you hate the high dollar liquid organic programs I am using.This comment is not a Dig. I just read all your posts because many are informative. Just an FYI This is my first and last time. Next grow will be all soil amendments and Tea's.

    Now to answer your question about the calcium. I use the agronomic Library as one of my research tools. I am not sure if it is legal to post a link to another website or not but here you go.

    Magnesium Basics

    Understanding CEC, Buffer soil pH, Percent Saturation

    These were 2 articles I read and tried to understand with my little knowledge of plant life. Maybe I misread or misinterpreted the information given. Have a look see for yourself.
  5. #5 MGB, Aug 1, 2011
    Last edited by a moderator: Aug 1, 2011

    Please don't get pissed if I ask why you say to do something. I am a person that needs to fully understand why I am doing something and not just do it because someone said so.

    So here goes. You say use dolomite. I agree dolomite is a source of magnesium. But, according to the Promix ingredients it already has Dolomite in it. Secondly everything I read says it is very slow acting. Last but not least my PH is running around 6.8 -7.0 depending on what the microbes want at that particular time. If I add more dolomite won't this raise it even higher?

    I am using both Humic and Fulvic Acid once a week with each feeding.

    Also I am unclear whether or not Epsom Salts are organic. I have gone through painstaking time and money trying to keep my grow all organic. But, I also know that I have many hours and about $600 in nutes for 12 plants. If this problem persists my final product is going to be less than desirable. I have read that without these main stem fan leaves I am severely handicapping my plant.

    Once again thank you for reply.
  6. MGB, thanks for the info. I always need a refresher on this stuff and there is no better place than to get it from LD. I saved your attached articles so I could study up again later. The rate at which I learn things is far exceeded by the rate at which I forget things.

    BTW, why don't you start now with your plants and get some Sul Po Mag, put a tbsp in a gallon(3/4 tsp in a quart of H2O) of water and shake it routinely over a course of 24 hours. You know, like when you walk by it now and then, pick it up and shake it good. In a day it will be dissolved, then water with it. Also, get some quality EWC and or compost and top dress with it.

  7. #7 jakrustle, Aug 1, 2011
    Last edited by a moderator: Aug 1, 2011
    MGB, one other thing. I just saw the pics of your plant. They didn't load up the first time I looked at your post. Having one set of leaves looking like yours is not something you should be too concerned about. When I had my best grow, I still had a dead fan leaf here or there. Overall your plants look pretty darn healthy. I guess my one piece of AMATEUR advice is don't overthink it. As healthy as your plant looks it might just need more of the food you are giving it. Are you giving at the recommended full strength? I also wondered if you have been using kelp teas or seaweed ferts or fish ferts.

    Far into most of my grows I have typically run low of Nitrogen which is why I THINK I lost fan leaves half way (4 weeks) into flower. Remember, I think I had that deficiency. Frankly, I think your plant is looking pretty damn good. Try not to sweat to much that you THINK that you are going to have a lower than expected harvest. Hell, I'd be happy as shyte to have your plant(s) in my closet/yard. Peace

  8. Just a couple of thoughts.

    One in organic growing you often hear less is more, this might be such a case. I have found you can add too much "good stuff" Not saying you did, but i'm thinking you might have over done your nutrient program. You might want to half your humic acid for instance.

    Two, for lack of a proper term I think your soil is confused, what i mean is you seem to have lost control of the ingredient interactions and are not sure what way is up. This locks out that, and that affects whatever, it all gets very confusing. Believe me we all have been there.

    I would go back to watering with water for the near term. And try to fix things with sprays, just small amounts of whatever fixes you think could help, such as epsom salt. Remember that sul po mag has K at (22?), so it could fix a K deficiency or make a K lockout worse. Your call here.

    I think the most common problem is what i call the two's, as in too much water, too little water, too many nutrients, too few, too many whatevers. So it is difficult to fix the two's with more of anything, unless you have identified a deficiency correctly. But a top dressing of ewc might help, I say might because I have found all ewc is not the same, the quality varies widely. Hopefully you can source some high quality humic content.

    Hopefully you can finess a decent result, but what you are learning right now is priceless and will no doubt help you in future grows. I truely wish there was a magic of luck.....MIW
  9. #9 wetdog, Aug 1, 2011
    Last edited by a moderator: Aug 1, 2011
    One thing IMO that screws a lot of people up is the term 'organic'. I prefer the term natural, as there are many 'natural' things that in a strict sense are not considered organic since they contain no carbon.

    Any of your limestone's or rock dusts are prime examples. Can't get much more natural than a rock, but it's not *organic*. Epsom Salts is not organic, not even sure if it's natural, but after using it for close to 40 years, I really don't care. LOL Makes a decent laxative and/or foot soak. Stuff does everything.

    BTW, even though my mix is well limed with dolomite, I still add epsom salts every now and then, about once/month. Even though the dolo has mag in it, either it releases too slow, or the plants need more than is supplied. I'll add a small handful to a 5gal bucket and water with it.

    MIW is quite right about the humic. Once/week is too often. Every 2 weeks is the soonest to apply and once/month works well also. Less is really more with this stuff.


    EDIT: Just re read and saw you have epsom salts on hand. As long as it doesn't have perfume in it (bath salts), you're golden. Mix some up and water your plants. Results are pretty quick, usually just a few days.
  10. Thank you all for advice. I have just finished top dressing all 12 plants with EWC. I just fed yesterday and buckets are still quite wet. On Wednesday when I water I will add one teaspoon of Epsom salts for every gallon of water the plants take. When I water or feed I continue to apply until I get runoff . (Approximately 20%) Is this a bad practice? I apply food and water to the medium with a very fine spray 1 gal at a time. It takes me approximately 6 hours to feed or water all 12 plants.

    Ok ,OK I am a little anal. Some people actually think I am a freak because I always try to be a perfectionist at everything I do in my life. Many many years ago my Dad taught me that if you are going to do something in life do it to the best of your ability or don't do it at all. This is why it eats at me if something is not right.

    MIW and Wetdog:

    Do you really think 1 ml of humic acid per gal. of water every week is to much? Not doubting you. Just asking because I never stated quantities I was using.


    You say my plants look good. The problem is I spend 4 hours every day debugging and making sure all bud sites are getting light and not being shaded by fan leaves. On Wednesday and Sunday I spend 8-10 hours with plants either feeding or watering them as well as debugging and training them. So with all this time I spend on them I notice any little thing about them that changes. Look at those pictures closer you will see that from the bottom up the fan leaves on the main stem are yellow to lime green in color. Also that was 3 different plants and 2 different strains I showed you. All 12 plants and all 3 strains have identical symptoms.

    Once again thank you all for your input.
    Have a great day!

  11. MGB on humic acid I'd go on the light side of the recommended rates. And I may have been a bit over dramatic, looking back at your pics they are not bad at all.

    I use powdered humic acid, SM 90, at 1/4-1/8 tsp per 5 gallons of water or just enough to color it light brown. I also use LC10+7 in sprays, it is 10% humic acid plus 7 minor minerals. I spray this at 1/4-1/2 tsp per gallon. I use one or the other fairly frequently, let's say once a week or every other watering/spraying but I use it at less than half the suggested rates.

    My thoughts are I already have humic/fulvic acid through high quality compost/ewc so what I add is just icing on the cake rather than the whole cake.

    When I add something new to what I know is good soil, I tend to go very cautiously so as to not screw up what is already working.

    Best of luck and for what it's worth take a break from baby setting your plants, it can be an obsession if your not careful......MIW
  12. @MGB

    I wasn't referring to the amount of the humic, but rather the frequency.

    What I use comes from BioAg, and they even state on the site not to use it more often than every 2 weeks. I usually go longer.

    6 hours for 12 plants?!? LOL, I'd never get to sleep. Between the mj and the veggies there are somewhere between 50-75. Never really counted them all.

  13. @MGB, How many weeks into flowering are you? Plants will naturally lose bottom leaves as they flower. Remember, when cannabis flowers it is because the plant is ending it's life cycle. It is an annual after all, and the final stage of an annual is to flower, then die.
    Quite honestly, it doesn't really look like a Mg deficiency to me, as most Mg defs start showing on the top leaves first.
    Also, what size pots are your plants in? Looks like smart pots, which means you'll have a denser root mass, so if you're in too small of a pot, you could be root bound which will make it difficult for your plants to feed properly.
    With all the said, your plants don't really look too bad.

Share This Page