Assistance please, rust/brown leaves.

[BigD66]

These girls are 6 weeks old, and in 2 gallons of FFOF. They are primarily outside, and we're topped a week ago.
I noticed the rust/brown spots on one yesterday, and

 

[Growrx]

Looks like Mag to me

 

[Wh1teScorp1on]

100% Mag deficiency. Use cal/Mag or epsom salts

 

[GNick55]

6 weeks old?
something else is wrong. plants should be bigger than that..

 

[RealizedReal000]

I’m pretty sure I see tiny white spots on your leaves. Check for bugs cause I had the same issue and it showed like that cause bugs were attacking my roots before I even knew it.

 

[BigD66]

6 weeks old?
something else is wrong. plants should be bigger than that..

They were topped a few days before I took the photo. But I agree, they should be bigger.

 

[BigD66]

100% Mag deficiency. Use cal/Mag or epsom salts

Never heard of a cal/mag deficiency in soil?

 

[Huntingterps]

High feeding plants need cal-mag no matter the medium. Depending on your water would determine how much in soil. You can amend it in or water it in but it needs to b there..

 

[Mostlymooses]

Yeah you can absolutely get cal mag deficiency in soil. Especially if you are using filtered water.

 

[BigD66]

Yeah you can absolutely get cal mag deficiency in soil. Especially if you are using filtered water.

Thanks. I’ll pick up some tomorrow.

 

[BigD66]

Yeah you can absolutely get cal mag deficiency in soil. Especially if you are using filtered water.

Thanks. I’ll add some tomorrow.

 

[william76]

I'd be sure of what's causing it before treating it,check for everything,(bugs,runoff etc).76

 

[RealizedReal000]

I'd be sure of what's causing it before treating it,check for everything,(bugs,runoff etc).76

I agree narrow it down cause bugs can show up as many deficiencies cause the roots are being attacked.