Mag/N Deficiency? PH issues? Yellow leaves/red petioles

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Kvdavesexyshad

Member
Hi everyone, been getting a lot of good info from this forum and hope to get some good insight to what my issue could be.

Medium is FFHF
3 gallon fabric pots
Temps 78-84F
RH 35-45%
Week 9 from seed, about 6 weeks since preflower
Strain is (likely) GSC auto; I say likely because I don't have much confidence from the seed bank I ordered from. Ordered GSC photos, got this auto instead.
Watered tap ph 6.3-6.8 from seed, started FF trio feeding around week 4-5 at 1/4 strength, now at half strength.
Noticed yellowing leaves at lower canopy a couple of weeks ago, thought it was Mag deficiency, added 1 tbsp/gallon epsom salt with water; still not going away; looking like the deficiency is progressing.
Top dressed dolomite lime about 1.5-2tbsp/gallon medium.

Lime will probably take at least a week or so before doing anything. Is my lime application too late? Is this a PH issue? I checked runoff PH (seems to be lots of differing opinions on the validity of this) and it was coming pretty low ~5.

I'm thinking it's a PH issue and thus magnesium deficiencies started showing and the lime might be too late to really fix this at this stage of the grow. What do y'all think?

The first photo is when I first started to notice, then the following photos are from a couple of weeks later.

Might be nothing I can do now but ride it out to harvest. The two plants on the sides seem to be yellowing out slower than the one in the middle. Note: I LST the middle one the most and it's the bigger one by far. Perhaps the middle one had too many branches to feed and thus started showing deficiencies earlier?
 

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goofy81

Well-Known Member
More importantly what's the runoff EC?

In this case, it looks like a nitrogen deficiency.
Now, don't go putting more N in because we don't know the cause

You have a bit of tip burn, so I'm going to assume the EC was too strong at one stage?
Salt buildup? check runoff EC ! you might have an abundant amount of N going in, but a high EC might be locking it out.
Probably because you were trying to mitigate it by adding more stuff,
 
K

Kvdavesexyshad

Member
goofy81 said:
More importantly what's the runoff EC?

In this case, it looks like a nitrogen deficiency.
Now, don't go putting more N in because we don't know the cause

You have a bit of tip burn, so I'm going to assume the EC was too strong at one stage?
Salt buildup? check runoff EC ! you might have an abundant amount of N going in, but a high EC might be locking it out.
Probably because you were trying to mitigate it by adding more stuff,
Click to expand...
Yeah I noticed tip burn early on when I started to feed so I slowed down on the feeding strength, but nothing was changing. This is my third grow and much better than my previous two, but I'm still learning.

I'm reading up on EC and how to measure it properly. I bought the blue lab PH pen and have been using that. Any recommendations on how to measure EC accurately?
 
K

Kvdavesexyshad

Member
So if I were to get a TDS/EC measuring pen, I imagine I SHOULD expect to see lower EC in my runoff than input. If I see higher, then likely I have massive salt buildup in my medium that's running off with each watering, causing a higher reading.

In an ideal situation, my runoff PH should stay roughly the same as input, and EC should be less than input. If significantly less, I may need to increase dosage for feeding. Am I understanding this correctly? Do I go by the EC recommendations of FF Trio guide? Or what's a good input/output EC reading guide to follow for each stages of grow?
 
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Booboo highkite

New Member
goofy81 said:
More importantly what's the runoff EC?

In this case, it looks like a nitrogen deficiency.
Now, don't go putting more N in because we don't know the cause

You have a bit of tip burn, so I'm going to assume the EC was too strong at one stage?
Salt buildup? check runoff EC ! you might have an abundant amount of N going in, but a high EC might be locking it out.
Probably because you were trying to mitigate it by adding more stuff,
Click to expand...
 
K

Kvdavesexyshad

Member
After doing more research into EC/TDS measuring
(Don't know why I didn't research this more to begin with because now it's a "duh" moment) I ordered the bluelab EC/TDS pen. I imagine if I test the runoff of the sickly one I'll have a better picture of what I'm dealing with.

Like @goofy81 suggested, I'm expecting to see that I'm either not feeding enough or I have some nutrient lockout on these, particularly the really sickly looking one.

Once I receive my pen, I'll keep this post updated.
 
JustBlazin

JustBlazin

Well-Known Member
To me it looks like your plants are hungry, and considering your soil(ffof) is 2 months old I'd bet it's depleted. But you were only giving it 1/4 strength up to 1/2 strength thinking the soil still had stuff in it.
I would Try giving it 3/4- to full strength and see if it helps or gets worse
 
K

Kvdavesexyshad

Member
JustBlazin said:
To me it looks like your plants are hungry, and considering your soil(ffof) is 2 months old I'd bet it's depleted. But you were only giving it 1/4 strength up to 1/2 strength thinking the soil still had stuff in it.
I would Try giving it 3/4- to full strength and see if it helps or gets worse
Click to expand...
My medium is happy frog, which is milder than ocean forest so you may be onto something.

I got my pen coming in tomorrow which coincides with my water schedule so I'll keep y'all posted.
 
K

Kvdavesexyshad

Member
Update: Got my TDS/EC pen and I have made some measurements and observations. Here's where I'm at currently @ week 9 from seed, roughly week 6 in flower.

First, here's the feed I applied (FF Trio):
15mL BB/gallon
5mL GB/gallon
7.5mL TB/gallon

Input PH 6.5
Input EC 2.5

Output PH 6.3
Output EC 4.5

It seems I fixed my medium PH issue but my runoff EC is through the roof. One thing to note (not sure if I mentioned this): my fabric pots were allowed to sit in their runoff this whole grow. I realize this mistake now and have corrected it for this feed. I believe I have salt buildup in the three pots I have growing, but the two that look the least sick were showing EC of a bit less at around 3.3, which is still not good, but not as bad as the worst one.

My plan is on the next watering to "flush" until my runoff EC seems healthier (say ~1.5-2.0?)
Is this a good plan? What do y'all think?
 
myke

myke

Well-Known Member
Yikes,you should have just given straight water to test,anyway dont take ph reading in runoff as bible. Means nothing.So your super high EC is from sitting in runoff.Like you said water till EC is more normal.Under 2, 1-1.5 is normal.
 
K

Kvdavesexyshad

Member
myke said:
Yikes,you should have just given straight water to test,anyway dont take ph reading in runoff as bible. Means nothing.So your super high EC is from sitting in runoff.Like you said water till EC is more normal.Under 2, 1-1.5 is normal.
Click to expand...
I've been trying to follow these charts another kind member of this forum has shared with me. Where do you get your EC ranges from? Is it just from experience?

My tap comes in at .5 EC, so I think if I remove GB now at this stage and just keep BB and TB I should be able to reach a lower EC reading.
 

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Kvdavesexyshad

Member
Wattzzup said:
Why ph? And why ph lower than the 6.8 recommended for soil? Your runoff ph is low. Add plain tap next time.
Click to expand...
Read that 6.5 was good for soil, rather 6.3-6.8 so I was staying in that range the whole grow. I did end up having runoff that crept low PH few weeks ago, around high 5s. I have since top dressed with dolomite lime and it seems to have brought it back up, but I will start watering at a higher PH now.
 
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