When to add Epsom Salt?

Budclarkson · Apr 20, 2023

New grower FNG but so far so good.

Growing autos indoors in Coco Loco soil.
About 4 weeks in starting adding CalMag every other watering.

About 1 wk into flower I started adding Jacks 321 but only mixing PartA and B as I did not have their Epsom Salt bag. Not sure it was needed when already using CalMag??

As the Jack’s epsom was going to cost me $50 shipped I passed and picked up a bag of organic epsom salt from Power Grow systems off of Amazonia.

Not sure how the concentration compares to the Jacks and how/if I should start mixing it with the Jacks PartA and B or just add it separately. Power Sustems says 1tsp per gallon which is a lot more in weight (grams) compared to the Jacks stuff…

Recently got a a TDS/EC meter and it measured 110ppm on tap water and 320ppm on the runoff with the Jacks A/B mix at 1/2 rate (maybe a little less since I used some water and not all nutes on the water/feed).

Thoughts on how to introduce the Epsom salt and at what rate? Both the Epsom abs CalMag have magnesium and don’t want to overuse it and start causing problems.

Thanks

ArtfulCodger · Apr 20, 2023

From a "pure" Jack's 321 standpoint, you wouldn't use calmag, and you'd include epsom salt in every feeding. 3g of Part A, 2g of Part B, and 1g of epsom, per gallon of water. Jack's changed the formula a while back, preserving the 3:2:1 ratio, but in slightly greater volume: 3.6g of A, 2.4g of B, and 1.2g of epsom. I run 100% coco with Blumats, feeding constantly, at 1.3 EC (650 ppm) in veg and 1.8 EC (900 ppm) in flower. I don't use calmag, and have not run into deficiencies (knock on wood).

Non-Jack's epsom salt is fine.

Budclarkson · Apr 20, 2023

ArtfulCodger said:
From a "pure" Jack's 321 standpoint, you wouldn't use calmag, and you'd include epsom salt in every feeding. 3g of Part A, 2g of Part B, and 1g of epsom, per gallon of water. Jack's changed the formula a while back, preserving the 3:2:1 ratio, but in slightly greater volume: 3.6g of A, 2.4g of B, and 1.2g of epsom. I run 100% coco with Blumats, feeding constantly, at 1.3 EC (650 ppm) in veg and 1.8 EC (900 ppm) in flower. I don't use calmag, and have not run into deficiencies (knock on wood).

Non-Jack's epsom salt is fine.

So next feeding I should introduce the epsom salt to the Jacks recipe and hold off on CalMag?
How often for the Soil based media do you think I should be feeding per week during flower, and veg for the next go? 30oz of fluid for 3 gallon pot sound right? I’m new to using thr TDS meter and don’t want to overdo it.

I have to figure out how to read the EC - units are in usec.

ArtfulCodger · Apr 20, 2023

Budclarkson said:
So next feeding I should introduce the epsom salt to the Jacks recipe and hold off on CalMag?
How often for the Soil based media do you think I should be feeding per week during flower, and veg for the next go? 30oz of fluid for 3 gallon pot sound right? I’m new to using thr TDS meter and don’t want to overdo it.

I have to figure out how to read the EC - units are in usec.

Everyone waters differently. In soil, I water only when the pot is light. I water to 10% runoff, which is typically about a third of the pot volume. I feed when my run-off ppms fall below 900 on the 500 scale.

mysticepipedon · Apr 20, 2023

Budclarkson said:
So next feeding I should introduce the epsom salt to the Jacks recipe and hold off on CalMag?
How often for the Soil based media do you think I should be feeding per week during flower, and veg for the next go? 30oz of fluid for 3 gallon pot sound right? I’m new to using thr TDS meter and don’t want to overdo it.

I have to figure out how to read the EC - units are in usec.

Get a hold of a water test report from whatever utility you get your water from. If it's not a utility, but a well, you have to have it tested yourself.

If there is a decent amount of calcium in your water, you should avoid cal/mag. I have 29 ppm Ca in my water, and adding cal/mag eventually creates a calcium-caused lockout, destroying my yield. I add a tsp. of epsom salts every time I feed, until most of the way through flower.

K.KrazyMyc · Apr 24, 2023

Mhhm...is there any SPECIFIC reason you want to add more magnesium...I'm seeing multiple sources of magnesium..
the jacks..the calmag+,the tap water..and the actual soil itself... unless you are seeing a mag deficiency.. I wouldn't bother with the epsom salt...especially since your already using tap water AND cal-mag+...

but like it's been said..start at 1 gram per gallon...it should raise ppm by about 110ppm....the majority being sulfur..and around 30-45 ppm magnesium...

K.KrazyMyc · Apr 24, 2023

my tap water ppm is 350~ppm...your lucky to have a decent source of water. It for sure has calcium.. as almost every water source in municipal cities has it.. so go for it,add 1 gram of epsom per gallon...if they're showing deficiency..give it 1.5-2 grams..

its generally SAFE to go high on magnesium...you won't destroy anything by accidentally overfeeding MAGNESIUM..

calcium however is another story,as the calcium itself can build up and cause a deposit in the soil , physically and molecularly causing lockout..

there are even some growers that used to or currently use epsom salts for their final "flush"...food for thought

Budclarkson · Apr 25, 2023

ArtfulCodger said:
Everyone waters differently. In soil, I water only when the pot is light. I water to 10% runoff, which is typically about a third of the pot volume. I feed when my run-off ppms fall below 900 on the 500 scale.

Using 3 gallon fabric Coco Loco with some added perlite. I water about 1/2 gallon with light run off.

Was using Cal Mag every other watering. Jack’s 321 without the epsom salt. Had just stopped Cal Mag when I got the epsom. It’s not the Jack’s brand as it was like $50 shipped for a small bag

When to add Epsom Salt?

When to add Epsom Salt?

Budclarkson

ArtfulCodger

Budclarkson

ArtfulCodger

mysticepipedon

K.KrazyMyc

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Budclarkson

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