Pre-mixing epsom salts a good idea?

If I had say 250L of soil, can I premix it with epsom salts? In my seedlings I can see that they have mag deficiency, so before I pot them to the bigger pots with the new soil batch, id rather adjust the new soil batch.

If premixing is the way ,roughly how much epsom salts should I add to 250L?

That is about 1/3 of a cubic yard, so about 1/4 to 3/4 cup should be fine....and yes you can premix, we do.

And another way to see it would be as 8.8 or about 9 cu feet or exactly .25 or 1/4 of a cu meter

so a teaspoon per cu foot would be just under .2 cups

a TBSP per cu ft would be .5 C for your 250L

you can also top dress that sprinkle and water in, and foliar that on to trigger an increase in vitamin/mineral production/absorption, but dont forget calcium too.

I personally don't mix it in at first, I always foliar it on twice a cycle, though, among a couple other choice foliars, but then I eventually top dress it, water it in, and after that last cycle then it gets mixed eventually and re-amended and re-inoculated.

Plenty of magnesium in coconuts as well as fresh live castings slithering with reds as well, in case you want a little less sulphur based option

@First Amendment Soil Il go for 1/2 Cup as both you and DonTesla mentioned the same amount, and see how the plants respond when planted.

@DonTesla Rather than top dress il probably mix in as the plants havnt been potted yet.
I can already see from my seedlings that the soil needs it, so foliar probably wont provide enough in my case.

As for Calcium I have Oyster Shell grounds which I will be mixing in when I add the epsom salts.

Thanks for the info re mag in coconuts/live castings, didnt know that...

Maersk said:

@First Amendment Soil Il go for 1/2 Cup as both you and DonTesla mentioned the same amount, and see how the plants respond when planted.

@DonTesla Rather than top dress il probably mix in as the plants havnt been potted yet.
I can already see from my seedlings that the soil needs it, so foliar probably wont provide enough in my case.

As for Calcium I have Oyster Shell grounds which I will be mixing in when I add the epsom salts.

Thanks for the info re mag in coconuts/live castings, didnt know that...

Click to expand...

my pleasure mang
how old are the seedlings if I may?

@DonTesla About 3 weeks old now. New shoots always showing light green

Epsom salts are highly water soluble! You can premix but you are losing a lot to run off. Epsom salts are best taken advantage of like Don said, through Foliar feed or root drench.

I'd recommend looking into Langbeinite, also sold as sul-po-mag and k-mag. You only need a relatively small application to provide long release Magnesium, along with sulfur and potassium. It's what my company uses in our water only soil blends and I wouldn't run any of my grows without it. It takes the labor out of having to worry about mag and potash.

@Rasta Roy Will definitely check that out, never used it before.