Mag or sulfur deficiency?

Noticed one leaf like this this morning, and a few others with lighter yellowing like it. Is this mag or sulfur?

Ilgm GDP
Flipped lighting to 12/12 2 days ago
2 plants in scrog growing in ffof soil, 7 gal pots. Soil was amended with 1 cup dolomite lime ea.
1- pH 6.3 ppm 1120
2- pH 6.5 ppm 1020
Earth juice nutes
Temps 75-81 day, 70 night
Rh 50-65 day 75night

I’m not 100%, but believe they look good, i’m thinking due to the recent change in lights they are going into flower mode and will look slightly different for a couple weeks while acclimating to the new light schedule. Did you change your nutrients from veg to flower nutes? I personally notice a slight difference when I move them into my flower room, changing light schedule and give different recipe for feeding. They usually bounce right out of it. Just my opinion, hope it helps a little, they look great, good luck!

Also I usually run my ph in veg at 6.2 and in flower at 5.9-6.0, not sure if that makes the difference for you?

I think you’ve got a magnesium deficiency. It’s common to see deficiencies when flipping to flower. A little Cal Mag should fix it.

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I added .75 tsp earth juice cal-n-mag/gal to the last two feedings in anticipation of the stretch. That’s why I was wondering if it was actually a mag deficiency or something else.

I can always up the cal-n-mag.

@Gfunk last feeding (2 days ago) was still the veg schedule. Next feeding will be flowing schedule. I did turn the lights up a bit from their veg. Not all the way yet, I’m trying to ease them into the full brilliance of my additional bridgelux strips.

Yes, I would use it full strength before it gets worse.

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This is " SULPER Deficiency "


This is " MAGANESE Deficiency "

This is " Magnesium Deficiency "

This is " ZINIC Deficiency "

These can be very hard to figure out. There is a few of us going thru the same thing including myself these past few day.


Manganese (Mn) Micronutrient and Immobile Element

Manganese Helps enzymes break down for chlorophyll and photosynthesis production,
as well as it works with plant enzymes to reduce nitrates before producing proteins.

Having plants that are deficient in manganese can turn the young leaves into
spotted (mottled) yellow and or brown areas on young leaves. Dead (Necrotic)
yellow spots form on top leaves, while the lower older leaves will or may have
gray specks and or spots. Symptoms can include yellowing of leaves while the
leaf veins can stay green. Can also produce a chequered effect. As the plant
gets newer growths the plant will seem to grow away from the problem, that’s
why the younger leaves may be unaffected. On the top of the leaves, brown spots
can appear. While the severe areas of the leaves turn brown and wither.
Parts Affected by a Manganese deficiency are: Young leaves.

Too much Manganese in the soil will cause an iron deficiency. The blotchy leaf
tissue is caused by not enough chlorophyll synthesis. Your plants will seem to
have very weak vigor caused by the excessive amount of manganese.

Problems with Manganese being locked out by PH troubles

Soil ph of over 6.5, High iron soils, Low nitrogen Soils, Dry weather
and compacted soil.


Manganese gets locked out of soil growing at ph levels of 2.0-5.0
Manganese is absorbed best in soil at a ph level of 5.5-6.5 (Wouldn’t recommend
having a soil ph of over 7.0 in soil) anything out of the ranges listed will
contribute to a Manganese Deficiency.

Hydro and Soil less Mediums

Manganese gets locked out of Hydro and Soil less Mediums at ph levels of 2.0-4.5
Manganese is absorbed best in Hydro and Soil less Mediums at ph levels of 5.0-5.6
(Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range
for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed
will contribute to a manganese deficiency.

Solution to fixing a Manganese deficiency
Foliar feed with any chemical fertilizer containing Mn., or mix with water and water
your plants with it. Any Chemical/Organic nutrients that have Manganese in them will
fix a Manganese deficiency. (Only mixing at ½ strength when using chemical nutrients
or it will cause nutrient burn!) Other nutrients that have Manganese in them are:
Manganese chelate, Manganese carbonate, Manganese chloride, Manganese dioxide,
Manganese oxide, Manganese sulfate, which are all fast absorption. Garden Manure,
Greenssand are both good sources of manganese and are medium/ slow absorption.

Now if you added to much chemical nutrients and or organics,( which is hard to burn
your plants when using organics) You need to Flush the soil with plain water. You need
to use 2 times as much water as the size of the pot, for example: If you have a 5 gallon
pot and need to flush it, you need to use 10 gallons of water to rinse out the soil good
enough to get rid of excessive nutrients.



Thanks to your lesson last week @garrigan62 , I now know the difference between magnesium and potassium deficiencies.


Magnesium deficiency it is :+1: Thanks for the help.

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Your welcome let me know how itorks out for you … ok

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@garrigan62, the information you are providing is just great and the explanations that are coming along with them I just think is class also thank you, Will :+1:.


Your very welcome. I’m glad i could help