Feeding a Mg-hog with organics

Hey RIU,

I'm a micro soil indoor grower and ever since I made the switch to led my plants have turned into magnesium eating machines. I need to repeatedly whack em with epsom salts else the tops immediately start lightening indicating deficiency. Without the epsom they've had it - plants literally collapse dead.

Will this repeated salts dosing impact detrimentally on soil life?

I've increased my compost (kitchen waste, coffee grounds, eggshells), and introduced a organic pelletised fertiliser of chicken manure, seaweed and blood&bone, plus activating herd with light organic fert of liquid blood&bone and molasses. This clearly isn't enough - seeing mg def in veg still.

How much epsom per gallon of soil should I preload with next time?

Any better mg alternatives out there in a organic paradigm?

So the switch from one light source (HID?) to another (LED) caused a Mg deficiency? Are you sure it's not the light/energy change influencing the growth pattern?

Switched from PLL fluro to LED - you can imagine its a lot brighter! Like switching from CFL to the sun, lol.

Just gotta rework my feeding and growing technique to cope with this brighter light. Trying to go proper big-boy organic with compost and all. Hope this makes sense?

This is my second LED run - so upped my soil inputs to address deficiencies I saw first time around. These plants have seen nothing but this led once rooted.

You shoulda seen it when I flipped my last flower cycle to LED halfway through - leaves turned black and became something like charcoal. Insane seeing an underfed plant cope with massive increase in illumination. Believe me - I knew I wanted to up the soil inputs on this run!

Have my first batch of alfalfa seed soaking - wanna try a sprouted tea and see what a little triacontinol will do.



Edit/ for the record I never needed added Mg under old fluro lights. Never needed much fertiliser either tho as intensity so low.

Hmmm, other random organic people are recommending 1-2 tablespoons of epsom per gallon of soil in initiall mix. Seems like a lot to me.

I had none in my initial mix as I hoped compost&fertiliser regime would suffice []

Hey bruv...I don't think you have a mg deficiency...as you talked about it showing in tops of your plantz...mg deficiency showz in the older leaves 1st.

I have just taken Epsom salts out of my soil and instead use it as a foliar application.

I use dolimite lime (mag) and gypsum (sulphur) as part of my soil mix.

smokey the cat said:

Hey RIU,

I'm a micro soil indoor grower and ever since I made the switch to led my plants have turned into magnesium eating machines. I need to repeatedly whack em with epsom salts else the tops immediately start lightening indicating deficiency. Without the epsom they've had it - plants literally collapse dead.

Will this repeated salts dosing impact detrimentally on soil life?

I've increased my compost (kitchen waste, coffee grounds, eggshells), and introduced a organic pelletised fertiliser of chicken manure, seaweed and blood&bone, plus activating herd with light organic fert of liquid blood&bone and molasses. This clearly isn't enough - seeing mg def in veg still.

How much epsom per gallon of soil should I preload with next time?

Any better mg alternatives out there in a organic paradigm?

Click to expand...

How long do you "cook"? And whats ur exact lime mix?

Yeah, was thinking this exact thing this morning. I only set that mix up a couple of weeks before dropping the plant in. Got more cooking already.

Ideally it should be 1 month plus right?
Reading Teeming Microbes and can imagine that with a too-short cook the biology will not have had a chance to start consuming, and the soil might thus exhibit poor nutrition despite being stuffed with goodies.
Hopefully things improve as we go - it'll be interesting to see.

Lime is nothing special - just powdered dolomite. Possibly could use more as put in 1 teaspoon per gallon.

Tested runoff this morning, showed 6.3 on the strips, water went in at 6.5. Had been wondering if I was seeing a Mn or Fe def, not an Mg, but my reading is that low ph shouldn't result in Mn problems. Mn is locked out @ 7+.

Just seeing clawed leaves, purple stems, very little stretch and what looked like some sort of yellowed def at the new growth.

Wondering if this was much more than a mag prob



So, with proper cooked soil I should be able to eliminate ph as a problem , right? And the plant will have access to better nutrients from same ingredients.

So for next plant:
I'm thinking cook soil 1 month minimum, and up dolomite to 1tb per gallon. Will also add 1tb per gallon of epsom into mix.

Is this a sensible way forward?

Thanks Chronikool - just saw your post now.

Epsom is super easy to add later so will leave out of my soil mix.
Will keep on eye on sulphur too. Hmmm,...

smokey the cat said:

Hey RIU,

I'm a micro soil indoor grower and ever since I made the switch to led my plants have turned into magnesium eating machines. I need to repeatedly whack em with epsom salts else the tops immediately start lightening indicating deficiency. Without the epsom they've had it - plants literally collapse dead.

Will this repeated salts dosing impact detrimentally on soil life?

I've increased my compost (kitchen waste, coffee grounds, eggshells), and introduced a organic pelletised fertiliser of chicken manure, seaweed and blood&bone, plus activating herd with light organic fert of liquid blood&bone and molasses. This clearly isn't enough - seeing mg def in veg still.

How much epsom per gallon of soil should I preload with next time?

Any better mg alternatives out there in a organic paradigm?

Click to expand...

It's my understanding there is no such thing as mg hungry strains. Plants use mg for the same thing, to make chlorophyll:

Chlorophyll a – C55 H72 O5 N4 Mg – single Magnesium ion
Chlorophyll b – C55 H70 O6 N4 Mg – single Magnesium ion
Chlorophyll c1 – C35 H30 O5 N4 Mg – single Magnesium ion
Chlorophyll c2 – C35 H28 O5 N4 Mg – single Magnesium ion
Chlorophyll d – C54 H70 O6 N4 Mg – single Magnesium ion
Chlorophyl f – C55 H70 O6 N4 Mg – single Magnesium ion

This is a little above my paygrade, so I'd would be interested if anyone had some different ideas on the mg. Personally, I think you have something else going on, like lights too close to the plants, watering problem, etc.

P-

Rather than mixing Epson in my soil, I like to dissolve the Epson and water every two to three weeks. I use 1 TBSP per gallon.

Pattahabi said:

It's my understanding there is no such thing as mg hungry strains. Plants use mg for the same thing, to make chlorophyll:

Chlorophyll a – C55 H72 O5 N4 Mg – single Magnesium ion
Chlorophyll b – C55 H70 O6 N4 Mg – single Magnesium ion
Chlorophyll c1 – C35 H30 O5 N4 Mg – single Magnesium ion
Chlorophyll c2 – C35 H28 O5 N4 Mg – single Magnesium ion
Chlorophyll d – C54 H70 O6 N4 Mg – single Magnesium ion
Chlorophyl f – C55 H70 O6 N4 Mg – single Magnesium ion

This is a little above my paygrade, so I'd would be interested if anyone had some different ideas on the mg. Personally, I think you have something else going on, like lights too close to the plants, watering problem, etc.

P-

Click to expand...

Pattahabi wins the thread.

A few weeks later and I have definitely figured it out - every plant being introduced to the cab exhibited the same bleaching on the upper most leaves, regardless of what they had or hadn't been fed or what they were planted in. It wasn't the soil or food, the water or airflow.

The answer: too much light.

Small cabinet, reflective mylar and I think what I was seeing was the chlorophyl in the upper growth just give up and abandon ship. As soon as I lowered the light level the leaves stopped clawing, growth surged and a few weeks later the plants are doing exactly what they should - get on with growing nice and green.

I've backed my light right down to about 25W - that's twenty five watts off of a single Vero 18 LED emitter. I used to flower with 240W of cool white CFL. Can't believe I'm using this little amount of power.

It might be that mylar just is so reflective and causing hot spots in such a small space.

The other thing that might be an issue is the light spectrum - I'm using a 3500K Vero which is slightly redder than ideal. A bluer led in 4000k would be better: penetrate the foliage more, as opposed to being absorbed in the top layer like red light does.


So, inter-vein chlorosis similar to mag def but on top growth, red stems and clawing leaves. In my case: too much light.

Glad you got this squared away. I was just going to say that Mg deficiency wouldn't be showing up
on the new growth, but someone beat me to it...