Epson salts - recommended concentration

[rbarata]

Does anyone knows the best/safe concentration?

A few years ago I made the calculations but I can't find it.
I believe I used to water with 5 ml (powder volume) per 2 liters of water.

Thank you

---------- Post added at 08:30 PM ---------- Previous post was at 07:51 PM ----------

Ok, I found 2 kg/1000 liters as a recommended dosage => 2 g / l

1 cc = approx. 1 ml

density = 1.68 g/cm3 (heptahydrate - MgSO4·7H2O)

So, 2 g / l equals approx. 1,19 ml of salt per liter.

[Brian1212]

2g/l seems a little bit high to me. Orchids generally need 1/4 of the strength of nutrients to other plants so I would go a bit lower with the epsom too, just my advice.

I would go with 0.5g/l and even lower if your nutrients already contains magnesium. You can always increase the dosage if it is not enough but feeding too much will cause damage you can't fix easily so I'd start lower and work up if you need to.

[rbarata]

In the past I used Epson salts without any damages or adverse results. I just can't remember (or find) what was the recommended dosage I used.

[SouthPark]

Originally Posted by rbarata

In the past I used Epson salts without any damages or adverse results. I just can't remember (or find) what was the recommended dosage I used.

One teaspoon per gallon of water is something I used to recall.

Can refer to a google search : "epsom salt 1 teaspoon per gallon orchidboard"

Maybe 1 gram or 1 teaspoon for every 3.8 litres of water.

So for X litres of water, the amount of epsom salt to add would be approximately :

X/3.8 gram for 'X' litres of water.

So if using X = 1 litre of water, then put in (1/3.8) or 0.26 gram (ie. roughly a quarter of a teaspoon) into 1 litre of water.

1 gram won't be exactly the same as 1 teaspoon of epsom salt. This is just an approximation.

[mook1178]

I don't think using density to calculate the volume of a pwder works.

If I want 2g/L then I weigh out 2 grams and add to a litre of water. The density means that the weight of 1 mL of saturated solution will weigh 1.68 g.

If you are following the weakly weekly, then I would add 0.5 g to 1 L

[thefish1337]

2g/L is 2000ppm... i feed about 20-30ppm every feeding. probably wont hurt but that is quite a bit

[SouthPark]

True ----- maybe go for something like 2g per 8 litre. Or 1 gram per 4 litres of water.

[camille1585]

Back when I was using magnesium sulfate on my orchids, I was using roughly 1g per 4 liters (volume of my watering can). 0.25g/l = 250ppm of MgSO4. Knowing that magnesium sulfate is 10% magnesium, the solution contains 25ppm magnesium, which is more than enough if you are using tap water.

[Ray]

Many consider the "MSU RO" or "Akerne's Rain Mix" to be good fertilizers. If we assume the Mg content was specified as being appropriate for the 125 ppm N dosage they recommend, then that is the equivalent of 0.71g/gal or 0.19g/L of Epsom Salts applied at every watering.

For most folks, a teaspoon/gallon added monthly is easier.

FWIW, I have applied Epsom Salts at as much as 2 tablespoons/gallon with no issues.

[WaterWitchin]

I can't do the math, but I've used 1 teaspoon per gallon on orchids for years, and my fertilizer has cal mag in it. Not all the time, but just when it looks like it needs it. I-2 tablespoons on my tomatoes, often. Because they're hogs.