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Millville, UT

I posted this same question on the fert and water message board but since more folks look at the General discussion board I thought I would ask it here too.
Looking at several Cal-Mag amendments I have noticed that they are derived from Calcium Nitrate and Magnesium nitrate. Can you get the same benefit by using Calcium Nitrate fertilizer and Epsom salt? I have read you should not mix Calcium nitrate and Epsom salt together but can you apply them on separate days?

7/6/2018 3:29:54 PM

Mill Bay, British Columbia

Are you wanting to add Cal-Mag due to a deficiency that has shown up, or are you just adding it to your rotation as part of your fertilizer program?

Yes, you will get some calcium by using calcium nitrate (and also Nitrogen) and you will add Magnesium (and Sulphur) if you use Epsom salts.

If it’s a Cal-Mag deficiency, then you’d be better off using a chelated product that is specifically designed to correct a deficiency that has been identified with a tissue test.

I use Cal-Mag Max that has 4% chelated calcium and 2% chelated magnesium that I can recommend.

https://growthproducts.com/pdfs/Hort_Cal_Mag_Max_7-0-3.pdf

7/6/2018 7:19:09 PM

New York

I’ve been using calcium nitrate and Epsom salts together all seasons I hope it doesn’t cause problems. I think I’ve seen on Ron wallaces diary he uses them together also.

7/6/2018 11:57:14 PM

Millville, UT

I have just been adding a little( 1 oz/week) calcium nitrate and epsom salt just as part of my fert program. I have read on several sites about if the two are together insoluble calcium sulfate which is unavailable to the plant: https://www.smart-fertilizer.com/articles/fertilizer-stock-solutions
Here is a chart showing which fertilizers are ok to mix together:
https://www.smart-fertilizer.com/Cms_Data/Contents/smart-eng/Media/other/Fertilizer-compatibility.jpg

7/8/2018 1:07:08 AM

Mill Bay, British Columbia

Great links, thanks for that.

7/9/2018 8:54:03 PM

New York

So will the calcium not be absorb by the plants or both the calcium and the nitrogen? I’ve been using calcium nitrate all season with same part emposom salt and my plants seemed to get greener

7/9/2018 9:13:46 PM

New York

I just found out that it turns into gypsum does that mean it’s not water soluble any more and where would the magnesium go?

7/9/2018 9:16:01 PM

Millville, UT

Regarding what happens to the magnesium is my guess is that it is still available to the plant along with the nitrate. It is the calcium that ends up being tied up and unavailable to the plant which is the whole reason for giving the plant Calcium nitrate in the first place. So this is my question. I assume it is ok to apply the Ca(NO3)2 on a different day than the Epsom salt. Since I dont have any Mg(NO3)2.

7/10/2018 4:43:53 PM

Millville, UT

As I am sure a lot of us do we have a lot of different fertilizers on our shelves (my wife says mad scientist). I plan on taking that fertilizer compatibility chart (there are many others I have noticed on the web) and figuring out what I can and can't apply together. I only am applying small amounts each day. My hope is that it is ok to apply non compatible fertilizers on different days. My hope is the plant will have taken up what it needs each day.

7/10/2018 4:54:25 PM