Magnesium? Not winning this deficiency

[Thebeginning1989]

Having this issue among multiple plants in my grow. I want to continue to say magnesium, but I don't want to hammer them hard with Epsom before getting second opinions. It is easy to see that there is yellowing between the veins, and growth is extremely slow.

Soil
Water at 6.5-6.8
Organic using dry amendments

[3Berries]

If it is Mg an epsom salt foliar spray would turn it around fast with out adding anything to the soil.

[Bluey]

Try keeping pH at the high end, even raising it if need be. Not real sure about soil but I think 7.0 is top range ok...check pH runoff also

[Thebeginning1989]

I'll do the next water with runoff to see if it is some sort of lockout.

[Blowdout2269]

I agree with 3Berries . It can't hurt to do a light foliar spray. If it shows improvement, then you know. If not, then you are able to rule that out.
The only thing I would add is - do not bombard your plants with a bunch of different treatments. Try one, and wait two weeks. Then try another. If you can't do that, you're better off doing nothing at all.

[Thebeginning1989]

I went ahead and did 1/2 tbsp for 1/2 gallon of water, and foliar sprayed. We'll see how it goes. I don't know why, but this is only happening to clones I start in 1 gallon fabric pots. My clones I start in a solo cup are growing healthier and much quicker. I have some new clones in solo cups that are outgrowing the older clones in the 1 gallon pots. So, I have a feeling if it is not only a magnesium issue, it might also be a watering issue. Weird that I can better gouge solo cup, 3G, and 5G watering, over 1G watering. Seems kind of dumb, but when I transplanted a 1G plant, the root ball was no bigger than half the 1G pot.

[OldManGrower]

What I see is a PH problem. Do you check your runoff? I'll bet you are running lower than you expect. The plants will not absorb nutrients if the PH is too low or high.

[Thebeginning1989]

Going to check the PH on the next watering for sure. I had figure when running organic PH would be less of an issue, but since it is reused soil maybe it is more acidic than I initially assumed.

[Blowdout2269]

My water is 8.5 and 130ish this time of year.
I pH with vitamin C, lemon juice, or ACV for organic.

[Thebeginning1989]

Yeah, the water PH is actually the same here, 8.4-8.5. I use citric acid to PH down, and I bring it down to 6.5-6.8; 1/8 tsp gets me down to 7.2-7.4, then I fine tune. Maybe I should just leave it as 7.2-7.4 since the microbiology should buffer the PH if the PH is not at an insane level?

[Mr.furley]

The microbiology you speak of is probably nonexistent in your dried out, clumpy looking, reused soil, by the looks of you soil in the picture above you've missed the best watering practices for the pot size and im think underwatered with used up medium is the root of the problem. Im also thinking you've answered your own question with the 1 gallon vs. cups comment, Small Plants will grow better/faster in a small pot vs. Rooting out in a large pot, start small and up-pot.

Did you amend it with anything before loading it back into a pot? Could you elaborate a little more on your soil situation?

[Thebeginning1989]

lol, Most of the clumps are small pieces of wood chips that came in fox farms soil. I had actually just broken up the top layer and did a top dressing before those pictures as they have been sitting in those gallon pots for longer than I want to admit. I may just transplant them at this point.

Before I reused the soil, I mixed, in a 27 gallon tote, 20 gallons of soil, and 50/50 mix of Dr. Earth home grown and flower girl. I realized too late that I should have also used earthworm castings, which I amended immediately with a top dress soon after planting. I definitely should have mixed earth worms castings with the initial mix of the soil.

After reading some more info in regards to reusing soil, I should have also probably used some dolomite lime in the amended mix as it seems soils such as fox farm become acidic (peat based?).

I'm beginning to think it is a PH issue AND watering issue at this point. I know what my next major purchase is, a soil PH pen.

[Bluey]

I have a soil pH probe..it's useless.

I measure runoff every week. Should do it more often but never really had issues in that area...and half strength nutes and regular flushes of pH balanced water during flower.

[Thebeginning1989]

The only problem with runoff is I read/watched that it was detrimental when growing organically using powder amendments. I did force run off on two of these plants, and got 7.1 PH runoff, which as I understand it can really mean nothing in a organic soil grow. I guess I can do a test, watering one with a lower PH and the other with the same PH, and see what happens, lol.

[Bluey]

Well that's where your problem is..at the roots

[Rwise]

When you adjust the PH do you then let it set for 24 hours and test again? Lemon juice, citric acid, VC in my experience are not stable and the PH returns to what it was before. I use mother natures sulfuric acid.

[Rwise]

A note on tap water, check with your supplier to see if they still use chlorine, many have switched to chloramine as mine has. This does not gas off and will need to be treated. This is a good place for the lemon juice as it kills the chloramine,as the other PH downs will. Also I put pelleted sulfur in my soil as a PH down buffer.

[Blowdout2269]

I've read Vitamin C will also kill chloramine. So I assume any citric acid will. What do ya think Rwise?

[Rwise]

Yes yes it will!

[3Berries]

Quite a few organic acids. Though it's only the inclusion of carbon in the molecule that makes them organic. I buy citric acid 10 lbs at a time for cleaning the water softener and adding to food in place of lemon juice. Great rust remover. Generally do not need a pH down with my mixes though.

• lactic acid
• acetic acid
• formic acid
• citric acid
• oxalic acid
• uric acid
• malic acid
• tartaric acid

[Bluey]

I use straight lemon juice (citric acid) to lower the pH.
Typically it holds quite well more than 95% of the time.
I have a tank I fill every 7 days or there abouts with 100ltr mix.
I do NOT aerate the tank.
I mixed this current tank 6 days ago and pH'ed it at 6.08pH. Today it is 6.08pH. When I mix it it's mixed aggressively with lots of aeration and I wait about 30 seconds to test it. There is no need to wait more than 15 minutes if mixing properly..
Last tank mix I mixed at 6.07pH and after 7 days it had climbed to 6.24pH or there abouts...which is quite unusual but it does happen occasionally.
I have a very accurate pH pen +/- 0.01pH accuracy, an Apera pH60 and calibrate it every few weeks...it doesn't drift much at all. About US$90. Buy it with extra storage solution and calibration fluids 4.0 & 7.0 from a reputable supplier. The cheap pens are good for the rubbish bin and do not produce repeatable results...don't use.

EDIT Going2fast wrote an excellent recent article of his experiences with pH pens here

https://forum.growweedeasy.com/forum/growing-community/587080-the-tale-of-two-ph-pens