Need help identifying a problem

Hey @Iron_Mike welcome to ILGM! It does look like a Cal/Mag issue but let’s tag some pros. In the mean time here is a link with more info.

@Midwestnewbie @Mrcrabs @BobbyDigital

Good luck!

Welcome @Iron_Mike . Try bringing the Ph up a little more to 6.5 for soil . Looks like cal mag with it starting at the bottom leaves first .


I echo @Seeddog soil ph sweet spot is 6.5 . Being that low will cause lockout. Welcome to all things maryjane @Iron_Mike.


Welcome @Iron_Mike

Hard to tell without much info. This could just be leaves not getting enough light or could be magnesium deficiency. Ph is a little low, depending on what medium you’re using, but is that going in or coming out? Need some support ticket info. @Jbum you have that handy? I can’t seem to locate it.

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Michigan eh? Yooper or Troll? Just curious.

Trolln baby! :wink:

That’s good to know. My well water is off my test kits chart alkaline and before we started correcting ph really saw what stunted plants look like. Not these, couple others. Corrected ph and within 2 weeks really came to life. Guess we’ll bring the ph up a bit.

Soil ph range 6.3-6.8 with 6.5 being sweet spot to much toward either end and can start locking out diff things.

Support ticket stuff-

White Widow from ILGM
Mixed soil in 7.5 gallon pots
Water ph about 6.0 to about 6.2 not runnoff

  • PPM/TDS or EC of nutrient solution if applicable Don’t know. Just using Miracle Grow pro.

Began life indoors in 4x4 tent untill I couldn’t manage temps any more

2 viper specter 450 lights using both veg and bloom

Temps were getting in the 90’s
Humidity was 50 to 70%

Have 1 circulating fan inside tent

4 inch intake and exhaust fans thermostatically controlled for 80 degrees.

Tent was in the garage and couldn’t keep temps down even with the doors open and a box fan moving garage air, so I put em out back of the garage in full sun.

Now it’s about 2 weeks later. Lots of new growth but have the yellowing.


You forgot me, shame on you …lmao just kidding my friend


Your plants have >>>>>

Magnesium (Mg) - Micronutrient and Mobile Element



Magnesium helps supports healthy veins while keeping a healthy
leaf production and its
structure. Magnesium is significant for chlorophyll-production
and enzyme break downs.
Magnesium which must be present in relatively large quantities
for the plant to survive,
but yet not to much to where it will cause the plant to show a toxicity.

Magnesium is one of the easiest deficiencies to tell… the green veins
along with the
yellowness of the entire surrounding leave is a dead giveaway, but
sometimes that’s not
always the case here. In case you have one of those where it doesn’t
show the green veins,
sometimes leaf tips and edges may discolor and curl upward. The growing
tips can turn lime
green when the deficiency progresses to the top of the plant. The edges
will feel like dry
and crispy and usually affects the lower leaves in younger plants, then
will affect the
middle to upper half when it gets older, but It can also happen on older
leaves as well.
The deficiency will start at the tip then will take over the entire outer
left and right
sides of the leaves. The inner part will be yellow and or brownish in color,
followed by
leaves falling without withering. The tips can also twist and turn as well
as curving
upwards as if you curl your tongues.

Excessive levels of magnesium in your plants will exhibit a buildup of toxic
salts that
will kill the leaves and lock out other nutrients like Calcium (Ca). Mg can
get locked
out by having too much Calcium, Chlorine or ammonium in your soil/water.
One of the worst problems a person can have is a magnesium def caused by
a ph lockout.
By giving it more magnesium to cure the problem when you are thinking you
are doing good,
but actually you are doing more harm then good. When the plants can’t
take in a nutrient
because of the ph being off for that element, the plant will not absorb
it but it will be
in the soil… therefore causing a buildup. A buildup will be noticed by
the outer parts of
the plant becoming whitish and or a yellowish color. The tips and part
way in on the inner
leaves will die and feel like glass. Parts affected by Magnesium deficiency
are: space
between the veins (Interveinal) of older leaves; may begin around interior perimeter of leaf.

Problems with Magnesium being locked out by PH troubles

Light Acid Soils, soils with excessive potassium, calcium and or phosphorus


Magnesium gets locked out of soil growing at ph levels of 2.0-6.4
Magnesium is absorbed best in soil at a ph level of 6.5-9.1 . (Wouldn’t
recommend having a
ph of over 7.0 in soil) anything out of the ranges listed will contribute
to a Magnesium

Hydro and Soil less Mediums

Magnesium gets locked out of Hydro and Soil less Mediums at ph levels
of 2.0-5.7
Magnesium is absorbed best in Hydro and Soil less Mediums at ph levels
of 5.8-9.1
(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 Magnesium deficiency.

Solution to fixing a Magnesium deficiency
Any Chemical/Organic nutrients that have Magnesium in them will fix a
Magnesium deficiency.
(Only mixing at ½ strength when using chemical nutrients or it will c
ause nutrient burn!)
Other nutrients that have magnesium in them are: Epsom salts, which is
fast absorption.
Dolomite lime and or garden lime (same thing just called different)
which is slow absorption.
Sulfate of Potash, Magnesia which is medium absorption. Worm Castings,
which is slow absorption.
Crabshell which is slow absorption. Earth Juice Mircoblast, which is
fast acting. (a must buy!!
Has lots of 2ndary nutrients).
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


My soil has a generous amount of fine sweet lime in it, along with Azomite and worm castings.

We are going to raise the ph a bit and see what happens.

Thanks for all the help.


I would ditch the MG as it’s too harsh and does not buffer the PH to an acceptable range. If you are using a test kit instead of a good PH pen to measure PH you should invest in one pronto. Nothing retards the life cycle of cannabis like being in the wrong PH range. Deficiencies will pop up and cascade on you inevitably.


How do you measure your ph? I have heard of a few different ways.

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Digital PH meter is the only method that works well. This is one I use.

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I’m definitely getting one of these. What if i wanted to check the soils ph in an outside plant, like one I have growing out in my swamp?20190718_192336|375x500 I haven’t been out there in a while but it too is beginning to show signs of problems. This one may actually be short on nitrogen and Mg, but if my ph is screwd up, well fix that first.

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Forgot to mention that is a half 55 gallon drum with mixed dirt like happy frog and other stuff. The bottom of the drum is cut out so roots get all the swamp water they want.

Look up how to do a slurry test.

Will test and transplant into another pot with mixed soil medium. I did my homework and got mixed messages when it came to FFOF soil. Some said they never got burned even with clones and other said they did. I believe it is how long the bags of soil sit during shipment and storage. The longer they sit the stronger they get. I’m here in Canuckville. Lol thanks again folks for helping me out. Last night I was going to feed them Calmag and glad I decided not to rush it and ask on the forum.