• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

Solution Needed, Tired of Using Bottled Cal-Mag

The3rdMan

Well-Known Member
I keep having magnesium deficiencies. Magnesium commonly comes from dolomite lime, epsom salts, greensand, or basalt rock dust. Even though I add amendments for magnesium, they seem not to be available to the plant when it needs it. So, I end up using a bottled liquid Cal-Mag (TPS Organic Cal-Mag, 1/8 Tsp per watering).

I don't understand epsom salts well enough to know how to safely use on my plants.

For those of you who don't have to add Cal-Mag to their organic soils, what amendments do you add to your soils that satisfies the plants need for magnesium?
 
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The3rdMan

Well-Known Member
Do you have a quality meter?

What did the pH test at?
The pH of both soil and water are fine. Soil at 6.8 and water between 6.0 - 7.0. My question is to those organic growers that have adequate magnesium in their soil and don't need to add magnesium. What amendments are they adding to soil so they do not have to add magnesium during the grow?
 
I use dolomite lime, but it takes time to break down even as a fine powder. But I reuse my soil and I’m 100% organic. Magnesium deficiency normally occurs a few weeks in when the soil is too acidic (below 6 for cannabis), cold, wet and the environment having high humidity. I water using enzymes regularly, this helps break down the organic matter and old roots, etc. Hence, the nutrients are more readily available to the plants quicker. Especially if you add the odd microbe tea. It’s always best to start with a soil within the correct ph range, it’s hard to correct and will take time. I would have said your ph is probably low, but you said it was actually quite high at 6.8. Over feeding can kind of mimic these deficiencies. I used different soils sold specifically for this industry on the same runs, I only get magnesium problems with the soils that are acidic. Calmag will help, but doesn’t quite hit the spot when the ph is out.
 

Northwood

Well-Known Member
Are you sure you have a magnesium deficiency? Obviously if you have soil tests done, then you know for sure. If not, magnesium uptake by your plants is influenced by a number of factors such as too much potassium. It's not uncommon for people to have magnesium deficiencies who add wood ash as an amendment. If you water to runoff, you may be leaching it out particularly if your CEC (caption exchange capacity) or pH is on the lower side. If you haven't done so already, I'd get a proper soil test done to eliminate these other common possibilities.

Apart from my initial soil mix, I don't add any inorganic amendments anymore. I just recycle biomass. I figure if a plant was healthy while alive, it has a perfect balance of nutrients, including magnesium, that will eventually be available to my plants.
 

Richard Drysift

Well-Known Member
I keep having magnesium deficiencies. Magnesium commonly comes from dolomite lime, epsom salts, greensand, or basalt rock dust. Even though I add amendments for magnesium, they seem not to be available to the plant when it needs it. So, I end up using a bottled liquid Cal-Mag (TPS Organic Cal-Mag, 1/8 Tsp per watering).

I don't understand epsom salts well enough to know how to safely use on my plants.

For those of you who don't have to add Cal-Mag to their organic soils, what amendments do you add to your soils that satisfies the plants need for magnesium?
For years I gave my plants gen organics calmag plus. It was the only bottled nutrient I was still using at the time. My water source is mostly dehumidifier water; especially during the summer months. It is stark; much like distilled water at 30 ppm. So I thought I would never be able to stop using calmag.
Somebody here told me I could get away from using calmag by providing it in slow release form. Problem is it takes awhile for good sources of calcium to break down and become available to your plants. So even if you start right now it will take a few months before you can toss out your calmag altogether.
One easy way to provide cal/mag naturally is to compost a shitload of eggshells either in a worm bin or compost pile. Collect the eggshell after you make an omelet or poached eggs on toast or whatever. Microwave the shells for a minute or two if there is any raw egg left inside the shells before throwing into a composter. I freeze them in a huge ziplock along with any coffee grounds, banana peels, and fruit/veg scraps etc to be thawed for “worm food.” Freezing speeds up decomposition so everything kind of turns to mush. It was about six months after we started composting eggshells before we could skip giving soluble cal/mag altogether. There are literally thousands of tiny pieces of eggshell all in my mix from the ewc.
In addition to composted eggshell you can add minerals as soil amendments to provide slow release macros. Amend the soil with calcium rich inputs along with npk sources and compost.
For every 1-3 cu ft of soil...Add:
1/2 cup of dolomite lime
1/2 cup garden gypsum
1 cup of crushed oyster shell flour
Add these in along with whatever NPK inputs and other amendments you choose. Be patient...it can take what seems like forever for some amendments; especially things like rock dust and green sand as you mention above to break down in your mix. The more active your mix is microbially the faster decomposition will happen. Adding more compost regularly whether in solid or tea form can help speed up availability of nutrients.
 

GrowRijt

Well-Known Member
Plain Epsom salt 1 - 2 tbsp per gallon. Spray on foliar or water in once a week. Done.

#2 item to add if you aren’t already is an arbuscular mycorrhizae. These little root symbionts help the plants breakdown elemental nutrients for uptake. Great white is well known and pretty expensive but totally works.
 

MustangStudFarm

Well-Known Member
I keep having magnesium deficiencies. Magnesium commonly comes from dolomite lime, epsom salts, greensand, or basalt rock dust. Even though I add amendments for magnesium, they seem not to be available to the plant when it needs it. So, I end up using a bottled liquid Cal-Mag (TPS Organic Cal-Mag, 1/8 Tsp per watering).

I don't understand epsom salts well enough to know how to safely use on my plants.

For those of you who don't have to add Cal-Mag to their organic soils, what amendments do you add to your soils that satisfies the plants need for magnesium?
How do you know it's a Cal-Mg issue? Diagnosing plant problems from looking at them is a very high level skill, I'm talking like the zen master or something. I started getting my soil tested for $30 and it has helped a lot to point me in the right direction. It turns out that I was constantly dealing with micronutrient(Fe,Mn) lockout, but it looked a LOT like N def. My phosphorus was WAY too high and iron/manganese levels were almost non-existent. I'm just saying "for instance" and saying that your problem will be the same. These soil tests have everything included in the kit: Soil measuring scoop, vial for soil sample, barcode to ID your order, prepaid lab fees, and prepaid postage to send in the vial. https://www.amazon.com/Soil-Savvy-Understand-Fertilizer-Recommendation/dp/B01GIMOG8A/ref=sxts_sxwds-bia-wc-drs1_0?crid=1Z741VSYV8AVM&cv_ct_cx=soil+savvy+soil+test+kit&dchild=1&keywords=soil+savvy+soil+test+kit&pd_rd_i=B01GIMOG8A&pd_rd_r=313e2087-865f-4a86-be32-ad5f68357bb2&pd_rd_w=qiNwc&pd_rd_wg=06tej&pf_rd_p=f3f1f1cd-8368-48df-ac69-94019fb84e3f&pf_rd_r=QMXQFZ8KP560EK82SQ5Y&psc=1&qid=1599003784&sprefix=soil+savvy,aps,278&sr=1-1-f7123c3d-6c2e-4dbe-9d7a-6185fb77bc58
 

MustangStudFarm

Well-Known Member
The pH of both soil and water are fine. Soil at 6.8 and water between 6.0 - 7.0. My question is to those organic growers that have adequate magnesium in their soil and don't need to add magnesium. What amendments are they adding to soil so they do not have to add magnesium during the grow?
I'm sorry, but I feel like you are asking the wrong question. You won't be asking the right question until you test your soil. I've never had Mg problems and it's one of the easiest to fix. Something else is going wrong... If your Ph is 6.8, then you are probably locking out micronutrients. I think that starts happening at Ph 6.5. I seem to do better with a low Ph as low as 5.8(because I'm always low in micronutrients).
 

loco41

Well-Known Member
I keep having magnesium deficiencies. Magnesium commonly comes from dolomite lime, epsom salts, greensand, or basalt rock dust. Even though I add amendments for magnesium, they seem not to be available to the plant when it needs it. So, I end up using a bottled liquid Cal-Mag (TPS Organic Cal-Mag, 1/8 Tsp per watering).

I don't understand epsom salts well enough to know how to safely use on my plants.

For those of you who don't have to add Cal-Mag to their organic soils, what amendments do you add to your soils that satisfies the plants need for magnesium?
What kind of light are you using too? I red some post in the led section about uv/violet wavelengths in the spectrum helping to aid in cal/mg absorption. I have not looked into this any further and am no source of knowledge at all really, but just another thing to keep you pondering on the solution.

Wish you success with the issue at hand though sir.
 

The3rdMan

Well-Known Member
Plain Epsom salt 1 - 2 tbsp per gallon. Spray on foliar or water in once a week. Done.

#2 item to add if you aren’t already is an arbuscular mycorrhizae. These little root symbionts help the plants breakdown elemental nutrients for uptake. Great white is well known and pretty expensive but totally works.
Seems a little excessive to me. Do you use this amount of epsom thru the entire grow?

"To avoid magnesium toxicity, the calcium content of the soil needs to be at least 10 times higher than the magnesium. So adding Epsom salt alone can cause that imbalance and create a toxic environment for the plants trying to grow".

I use Recharge every 7-10 days.
 
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The3rdMan

Well-Known Member
What kind of light are you using too? I red some post in the led section about uv/violet wavelengths in the spectrum helping to aid in cal/mg absorption. I have not looked into this any further and am no source of knowledge at all really, but just another thing to keep you pondering on the solution.

Wish you success with the issue at hand though sir.
I use MH and HPS.
 

The3rdMan

Well-Known Member
I'm sorry, but I feel like you are asking the wrong question. You won't be asking the right question until you test your soil. I've never had Mg problems and it's one of the easiest to fix. Something else is going wrong... If your Ph is 6.8, then you are probably locking out micronutrients. I think that starts happening at Ph 6.5. I seem to do better with a low Ph as low as 5.8(because I'm always low in micronutrients).
Most everything I see for soil pH recommends pH between 6.0 and 7.0 pH and 6.3 - 6.8 as ideal for cannabis.

"If the Ph range of the substrate is lower than 7.0, then magnesium can be easily absorbed by cannabis plants. But if the soil is very acid - lower than 5.0 - magnesium won't be assimilable by the plants."
 
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GrowRijt

Well-Known Member
Seems a little excessive to me. Do you use this amount of epsom thru the entire grow?

"To avoid magnesium toxicity, the calcium content of the soil needs to be at least 10 times higher than the magnesium. So adding Epsom salt alone can cause that imbalance and create a toxic environment for the plants trying to grow".

I use Recharge every 7-10 days.
I use a complete fert that has all the necessary nutrients built in so I don’t worry about this stuff. But if you are seeing Mg issues yes watering some in once a week or less should be fine. Go on low side and move up. Recharge should be good for the mycos. Not too sure what the issue is with just adding cal mag as well. Maybe you are overthinking this.

if you are doing recycled soil then I would agree on the soil test. It can be surprising what they find.
 
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