[bigjdawg]

I have a constant magnesium problem that I can't figure out to save my life. Every time I switch to flower I have a magnesium problem that sets in almost right away and I have to battle it the whole rest of the cycle. I have used multiple mixes and every time it happens. I've used Lc's mix and dank Frank's mix and Coots. Same problem in all three mixes. I just need guidance on what I'm doing wrong and how I can fix it.

Currently im using lc's base mix #1 with 1 cup of dolomite per cubic foot.
Peruvian seabird guano 2/3 cup 12-11-2
Indonesian guano 2/3 cup 0-7-0
Worm castings 1 cup
Maxicrop 1-0-17 1tspn per gallon
Added to 5 gallons of dechlorinated water and brewed for 24 hrs. Used at every watering in flower

Even with the dolomite lime and worm castings I'm not getting enough mag. I even switched from wiggle worm castings to high quality castings I get at build a soil because I read that if you use high quality castings you should never have a problem with magnesium. That didn't help either. There have been cycles where I've added 1/2 a tspn of Epsom salt per gallon every watering and still didn't fix the problem. I've even recently been using genral organics calmag every other watering and it has helped some but hasn't fully fixed the problem. I thought about adding it every watering but I didn't want to make things worse with the extra calcium when I'm only having a magnesium issue. The only time I really see improvement is when I use Epsom salt as a foliar. That makes me believe that the soil is either deficient or for whatever reason the plants can't get the magnesium from the soil because something else is locking it out ? I am at a loss and don't know what to do to fix the issue. I am planning on dollar feeding one time a week with Epsom salt on my next cycle if I have to. Any help would be very much appreciated. I know the problem is in the soil and I just need help fixing it.

[BurnOne]

Two questions just to cover the basics...
Are you using powdered dolomite?
Are the leaves pointing up like they're praying for magnesium?
Ementary questions I know but we need to cover all the bases.
Burn1

[MJPassion]

I thought praying was a good thing?

Anyway,
It sounds like you've got a lot of bicarbonates in your tap water.
Bicarbs will lock out Mg.
It may also be the case that your plant just wants more.

Also,
Only foliar feed Epsom salts.
It'll cause soil compaction if added to you watering can.
Soil compaction will lead to other issues.

[bigjdawg]

BurnOne: Yes it's powdered dolomite lime I believe the maker is greenway biotech. 22% cal 11% mag. It starts as yellow interveinial chlorosis on the lower older leaves and works it's way up. If it gets really out of had the leaves turn fully yellow and brown and fall off. I'll snap some pics tonight when the light comes on. I'm just confused why the plants can't absorb the mag. I know there is mag in the dolomite and the wotmcastings plus some in the maxicrop also.


MjPassion: would a water filter fix that if it were the problem. I know our local water comes from the river and is treated with chlorine.

[growingcrazy]

Do you have pictures?

What pH are you watering at?

My guess is P and not Mg.

Originally Posted by MJPassion

I thought praying was a good thing?

Lack of Ca.

[BurnOne]

Usually with a Mg deficiency the leaves point upward. Yellowing is a sign of nitrogen deficiency. Pics will definitely help.
Burn1

[bigjdawg]

Growingcrazy: I don't ph anything since I'm using dolomite in organic soil to buffer ph.

BurnOne: It has the interveinial chlorosis showing first. If I leave it alone or don't fix the deficiency then it progresses to the whole leaf turning yellow and brown and dying off. When I do use the Epsom salt the whole plant will green up and look good. I'll stop using it and the problem will return. Not right away but not long after stopping the Epsom salt. I'll definitely get some pics though since I'm sure my explanation isn't very good

[Limeygreen]

I would either do a water test for mineral content and pH or use ro water/spring water. Just because you us dolomite doesn't mean your pH of you water and soil don't matter, what is your soil pH? too low of a pH will also cause mg lock out, it's not available at those low pH's. P will also cause lack uptake lock out of mg if you have too much, too much sulfur as well. The browning you speak of, it starts as spots correct?

[bigbadbiddy]

I'll be honest: I just skimmed over this.

BUT:
I think I have the (albeit simple) solution for you since I ran into something very similar.
I run organic soil, the plants looked great in veg but in flower, way too early, they started to show various deficiencies.
I narrowed it down to N and Mg deficiency by doing some research online.

And while my plants did indeed need more N in particular and Mg as well (I later changed the ratio of my soilmix to include 1 more part of EWC --> N deficiency fixed since - and a bit more epsom salts --> Mg deficiency fixed since), the deficiencies were caused much more by me not PHing my water.

I also believed that my soil would do the PHing/buffering for me, the dolomite lime etc. etc.

This is not inherently wrong, the soil does that for you, to a certain degree.

What I later found out was that me adding Canna Bio Rhizotonic and/or Bio Boost was what caused my water PH to go all out of whack and the nutes starting to be locked out.

So my soil mix could use some more EWC and Epsom Salts at that point in time but that was not the main culprit.

The main culprit was me not PHing my water and using chemical nutrient additives on top of the organic soil (which further threw the PH off).
The PH was likely way above 7 over long periods of time and at that point all kinds of nutes get locked out.
I am honestly surprised at the quality I pulled without PHing my water.


I have since adjusted my habit and PH before every watering to be in the 6.3 range and the plants are very happy with it.
I do however need to add EWC to my water and make a slurry or after about 3 waterings the plants face an N deficiency again. Like I said, I remedied that by adding 1 more part of EWC to my soil mix since then.



So long story short:
PH your water. Until you do, you can't tell which nutes are simply being locked out and which you actually need to add.

[bigjdawg]

These are all in dank Frank's mix I was thinking there might be a slight potassium problem on a couple also I did add some maxicrop soluble powder tonight