Epsom salts

shantishanti

New Member
Hi peeps
I am about to mix up my next batch of soil. Last one went well with the only noticable problem being magnesium(and those little gnat bastards). I added dolomite lime to balance the ph but it musnt have provided enough magnesium for growing under leds...
How much epsom salts can i add (per cubic foot) without adding to much salt to the soil?
Thanks!
 
Best to water or foliar spray. Not really salts, it magnesium sulfate. Dolomite lime should take care of your cal/mag problems. If signs of mag deficiency start to appear try 1 tbs per gal of water and foliar spray to the point of runoff, every other week should take care of your mag problems.
Good luck.
 
Yeah i was hoping the dolomite would have taken care of it aye i added a fair bit and composted the mix for over two months. These leds mag them mg hungry as all hell.
Cheers for the input buddy
 
Do i need to give my plants cal mag when i grow in soil using organic nutriens and led light?

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Do i need to give my plants cal mag when i grow in soil using organic nutriens and led light?

Sent from my SGP311 using 420 Magazine Mobile App

I think it's probably dependant on the make up of your soil, wether you have bone meal for example.


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Yeah i was hoping the dolomite would have taken care of it aye i added a fair bit and composted the mix for over two months. These leds mag them mg hungry as all hell.
Cheers for the input buddy


Dolomite Lime has a Ca to Mg ratio of 2:1.. in organic soil we want to see a Ca to Mg ratio closer to 7:1 or more, so way too much Mg in Dolomite Lime.

Why are you asking?? I sounds like your first post said something about gnats and you think it's due to a lack of Mg...??? Not sure where that is coming from. Generally ... the closer the ratio of Ca to Mg (like is in Dolomite Lime) you will actually have MORE issues with pests and disease!

If you have insects .... try some Monterrey Garden Spray and dilute to 1 tbs to 1 gal of water and spray the plants and the soil.... bugs gone.
 
Best to water or foliar spray. Not really salts, it magnesium sulfate. Dolomite lime should take care of your cal/mag problems. If signs of mag deficiency start to appear try 1 tbs per gal of water and foliar spray to the point of runoff, every other week should take care of your mag problems.
Good luck.

When I make up a 1 bag mix of SubCool's supersoil, I add 1.5 tablespoons of epsom salt to the mix... and 1 tablespoon of dolomite lime. This is for approximately 10 gallons of soil. Go easy on this stuff.. it is very powerful.


Fwiw, here is a little info on Epsom salts to throw into the mix.

5 ml mixed into one gallon of water gave me a reading of 420 ppm/(0.84 EC) on my meter.

A full dose (5ml/gallon of water) of Botanicare calmag gave a reading of about 150 ppm/(0.3 EC) and contains roughly 2/3 Calcium and 1/3 magnesium.

What this means is that 5 ml of Epsom salts in a gallon of water is roughly ten times as much as you'd be getting from a full dose of CalMag. A tablespoon/gallon would be about 25 times as much.
So yeah, the stuff is strong.

That's assuming the magnesium in the ES is available to the plant in the same way as is the magnesium in the calmag, and there aren't other factors I'm missing. Because people do seem to get away with using these large doses. I often see that 1 tsp/gallon recommendation.
 
In organic soil I don't see what the need for CAL/MAG is other than to relieve your wallet of the paper goods. Kelp meal has everything cal/mag has in spades plus a truckload of other goodies .... not even going to talk about price comparison, its not even close....

Cal/Mag = 2/3 Ca to 1/3 Mg = 2:1 ratio same as Dolomite lime. Proper ratio s/b 7:1 or higher is better. Why I suggest Kelp Meal..

Don't believe me google is your friend, here's a good read:

Dolomite Lime – How Garden Lime Can Cause Problems
 
Talking to me Bb? You're preaching to the choir then... I wouldn't expect anyone to need calmag in organics either.

All good WC...

No, I was generally speaking here. Thanks for pointing out the ratio in the CAL/MAG. I've never used it and so I would know little of its use and makeup other than with organic soil we have other methods to resolve the same issue without having to spend money and get into the bottled paradigm.

Reason for not getting back to you right away cause I wanted to figure out what the deal is with the Cal/Mag and Epsom Salt.

Epsom Salt, I tried it a few times in soil when I was younger learning organic soil. An old friend of my mothers had a greenhouse and always supplied my mother and us with peppers and tomato starts from clone - the heirloom varieties. She was an organic farmer too and showed me how to add a tbs of Epsom Salt to the hole when transplanting tomatoes outdoors. Supposedly to help with blossom end rot.

Was a disaster for me and I never used it again other than a foot bath which BTW, we humans apparently need a lot more Mg than plants do for some reason. Could be that pesky thing in plants called Chlorophyll. We humans don't have much of that unless :smokin:


The reasoning behind that is the chemical make up of Chlorophyll (a) = C55H72O5N4Mg <-- only one atom of Mg there so plants don't use much.


So plants need very little Mg - Epsom Salts = Magnesium Sulfate. I would suggest that when we use Epsom Salt and plant responds well, it's likely due to the "sulfate" portion of the mix. Sulfur is a critical element needed for plant health and probably one of THE most over looked elements.

Epsom Salt is actually heptahydrate sulfate mineral epsomite (MgSO4·7H2O). The organic version is actually created from ... wait for it...... Dolomite limestone! Go figure that eh?

I guess my issue with the use of Cal/Mag and or Epsom Salt (wonder why is always capitalized?), is we are talking organic gardening and also mainly container growing. We will quickly have WAY too much Magnesium if used as part of a regular watering routine or even 2-3 times a cycle. Then I would have to dump soil and re-populate containers with fresh soil. I think that is counter productive even IF it was considered organic.

With the use of Cal/Mag and or Epsom Salt, Mg toxicity will quickly become an issue in containers with a properly mixed soil.


Here's a little info bomb - Epsom Salt is ONLY allowed to be used in Organically labeled food IF the soil has been tested and the results for Mg are in the LOW range. Very unlikely in container gardening ... more of an issue with Corn that's been grown in the same field for 6-7 years in a row. We know that's not going to be organic anyway. So no point to use it and that's my point.

Also ONLY in the USA is it considered Organic with a soil test with Mg deficient soil (everywhere else in the world NOT organic). I think Dolomite Limestone is an organic amendment...slow release.. I don't advocate its use due to the Ca/Mg ratio of 2:1 since the proper ratio is 7:1 or higher.


I'm going to offer up a much better alternative to a "possible" Cal/Mag deficiency... Some cannabis plants exhibit early yellowing in flower. Everyone jumps on Cal/Mag Epsom Salt wagon... I would suggest a soil test and find out IF there's actually any issue OR maybe it's the cultivar/phenotype expressing herself naturally. Only way to tell whats what is a soil test. Think of all the pretty fall colors .. ooh la la....

Cal/Mag - Epsom Salt substitute:

1 cup of Kelp meal - soak in quart of water overnight.

In the morning put contents in a food processor and blend for 10-20 seconds/ Pour back into the quart jar and put in fridge.

Wait for the kelp and water to separate. Pour off the water into a few gallons and water in.. also can add it your IPM and spray on. Suggest 2-3 tbs per gal water... you will have extra. Use with IPM until used up.

With the kelp left over put in the fridge and every say 3rd watering add a tsp to your water ... there' s a 6 month supply of Cal/Mag+ / Espom Salt for a few pennies and it's organic.

If used as a foiler... watch out! Goodness follows and it's dramatic. Overnight result.

This solution is not going to stop senescence (yellowing leaves) but it will eliminate the "Cal/Mag" deficiency.

As an aside... don't water in Calcium. It doesn't work, I tried (why I'm not sure - I call stoner moment). Kelp Meal has Calcium...

Everyone that made it this far.... you local County Extension Service (USA) has a soil test program. It cost me $9 per test here in PA... should be similar everywhere else in the states. If anyone would like help getting a test kit mailed to you I will help you figure it out. Many states the kits are available locally. I bought kits at my local nursery the other day and will start a new thread about it when I get my results back.
 
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