Magnesium Deficiency?

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eighties

Member
Need some help guys. This is a northern lights at day 11 of flower. She's been showing this mottled color for a while now and I'm not sure what it is, but thinking maybe a slight magnesium deficiency. This is a soil grow (black magic) using FF trio. I started at 1/4 strength, but have worked up to 1 gallon of full strength per week. I'm alternating water and the gallon of nutes. Overall, the plants are pretty happy and growing well, but not sure about this color. She's been a real touchy bitch despite been supposedly easy to grow. I've had to keep the nutes pretty low because she keeps showing yellowing or browning tips. Oh, and lights are 300w of HLG QB132 at about 16" in a 2x4 tent. Any help would be appreciated.

Edit: I ph everything that goes in to about 6.5. Haven't checked the runoff in a long time because its tough to get at and I rarely have much. The stems are mostly green, but some do have some purple stripes. The petioles start green, but turn purple as they mature. Also, the water I'm using is pretty good city water with chlorine that has been degassed for 24-48 hours prior to use.
 

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Phatty McSpinner

Member
Hey. I'm not a good one to help you diagnose that, but I do have a Northern Lights girl that is almost finished, and I noticed nobody else responded yet.

This plant could take anything in veg but like yours got a bit picky in flower. I had my own issues (you can see in my post today) but she is finishing well now.

To me your pics look more like a Calcium defciency than Mg, but again I am not the one for that. I am pretty sure mine was short on Mg at one point and it looked different.

I'm about 5 weeks ahead of you but I have some pics from around the same time you are now.

One thing I can tell you, and that I slightly f'd up on, is that the NL seems to like a lot of N, even way into to flower. You should be near the middle/end of your flowering stretch and she wants the most N for that. BUT, also be careful because right after that it will need alot less, but still some N almost to the end (for this strain according to other growers).

Also, watch out around week 6 of flower for the last problem I ran into. Also I am in mostly coco, not soil, so this one could get you even worse if not anticipated. Around week 5-6 she stopped drinking suddenly. I obviously have root issues, but it is normal for them to drink much less around the end. The problem is that this strain still wants nutes, but you don't want it sitting in water. Not sure if a solution would be to use much less water, but at a bit higher concentration? (need a pro to step in and answer that).

Anyway, you are not there yet. I think you might give her some N, check you root health, and maybe a Calcium supplement, if any expert can confirm that.

Folier feeding did wonders for my (suspected) Mg deficiency in veg, but most people dont want to do that in flower, unless you are planning to wash your buds.

Here's what my NL girl looked like a few weeks ago, where yours is now. Pretty similar I think. You should be good.

[pic are named by the date. first day of flower was 12-3-18. if you want to see them now, in week 7.5, check my other post]
 

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JohnDee

JohnDee

Well-Known Member
Eighties,
I don't see a Mg deficiency there, but like Phatty said...could be Ca related. Are you using tap and is it hard water or soft? Easy to get excess Ca if you have hard water. Problem is it's sometimes hard to determine whether it's a def or an excess.
JD
 
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eighties

Member
Thanks, guys. I gave her some epsom salts yesterday, so I'll know whether that's helping soon. If it doesn't start to correct in a week I'll think about some calmag. Whatever it is is pretty minor and doesn't seem to be affecting her too much, so I want to go slow and keep it simple. The epsom salts won't hurt, so that's a good place to start. I don't think its an N issue as the bottom isn't yellowing more than the top and the pattern is more mottled than uniform. It's really not yellowing as much as 2 different shades of green. Could even just be a pheno thing I suppose, but not too likely. I'll go slow and keep an eye on her. I'll update when I get some results.
 
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Phatty McSpinner

Member
Yeah, and remember what JohnDee said at the end, unless you already know what's in your tap water. I also notice now in one of your pics it looks like the NEW growth is equally affected, which would point to an immobile nute and not Ca or Mg. Your girl does not look too bad though, I think you're fine.

My comments on N were not related to your current issue but as preventative for what's next, based on my current grow of the same strain. You may not get this since you are in soil but in my case it was very sudden, around week 6-7. When this happened earlier (during flowering stretch) it was easy to fix because she was drinking a ton. This time it was right before she stopped drinking.

In both cases, there was a general paling of the leave color first, like you have in 2 of your pics.

[here's a couple more pics of my NL plant. Sorry, one of them is terrible quality, but you can still see how much yellowing between weeks 5 and 6.]

As you can see in my other post, it's too late to do anything now (less than week before chop), but she's finishing ok and doesn't seem to be as concerned about being yellow as I was.
 

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shawnery

shawnery

Well-Known Member
I just dealt with the same thing but more pronounced. I added cal and mag to be safe and the progression stopped. I thought it would be better to keep the ratios to one another similar.
 
raratt

raratt

Well-Known Member
shawnery said:
I just dealt with the same thing but more pronounced. I added cal and mag to be safe and the progression stopped. I thought it would be better to keep the ratios to one another similar.
Click to expand...
I did the same a couple weeks ago, along with some bloom nutes and nothing changed, the plants are almost naked now. I gave them some nutes today with N in them hoping for a change. I have no idea what is up.
 
raratt

raratt

Well-Known Member
I will do a close inspection on the soil. I have neem oil I could water with and I can get the mosquito bits from my local hardware store if needed. I know I can't get the neem on the buds in flower, not sure if it would help the roots..
 
Delztronics

Delztronics

Well-Known Member
eighties said:
Need some help guys. This is a northern lights at day 11 of flower. She's been showing this mottled color for a while now and I'm not sure what it is, but thinking maybe a slight magnesium deficiency. This is a soil grow (black magic) using FF trio. I started at 1/4 strength, but have worked up to 1 gallon of full strength per week. I'm alternating water and the gallon of nutes. Overall, the plants are pretty happy and growing well, but not sure about this color. She's been a real touchy bitch despite been supposedly easy to grow. I've had to keep the nutes pretty low because she keeps showing yellowing or browning tips. Oh, and lights are 300w of HLG QB132 at about 16" in a 2x4 tent. Any help would be appreciated.

Edit: I ph everything that goes in to about 6.5. Haven't checked the runoff in a long time because its tough to get at and I rarely have much. The stems are mostly green, but some do have some purple stripes. The petioles start green, but turn purple as they mature. Also, the water I'm using is pretty good city water with chlorine that has been degassed for 24-48 hours prior to use.
Click to expand...
Give enough water to check the run off man.
 
JohnDee

JohnDee

Well-Known Member
eighties said:
The epsom salts won't hurt, so that's a good place to start.
Click to expand...
Eighties...I saw this comment and felt compelled to comment. MagSulphate (Epsom salts) is a chemical nutrient additive and does need to be included in total ppm calculations. You can burn a plant with too much of anything. So don't assume that it's benign.

My comment is meant mostly for other people reading...
JD
 
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raratt

raratt

Well-Known Member
Dug down into the soil to the roots on the side of the pot and saw nothing. My soil pH meter shows approx 6.6, saw a singular fungus gnat however I have other plants in there also. I don't water until they are dry.
 
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