Yeah I've seen this problem occur in quite a few autoflower grows around this time, I'm relatively confident it's to do with the stretching - someone in this thread also mentioned they use a lot of energy in this stage.
Take a look at my plant. This really looks like all the photos I see of magnesium deficiency from my research.
Yours looks like Mg,have you tried epsom salt?Foiler or just dilute in water.
Looks like an iron deficiency.
I lay the food to them the first 3 weeks in. Level out, then cut back. Make sure your CalMag has iron in it. I've had this happen. I upped the CalMag+iron by 3ml. So I was giving 7ml of CalMag+iron. Sounds like a lot, but that's what my ladies needed.
Yup, fed with 1 tbsp epsom salt per gallon of water a couple of days ago. My understanding is these leaves are not going to recover but I should see deficiency stop. Any idea how long it takes to see progress? I think I read somewhere Mg deficiency exists for 4-6 weeks before becoming apparent?
Yeah I think my issue was N and Mg, and I am slowly getting on top of the N, which is why the chlorosis is more evident between veins now - hopefully the increase in CalMag will help here (gone from .2ml per litre, to 1ml). I have extremely soft water (50ppm), so it's very plausible that there just isn't enough in there, and it's finally caught up with the plant.@Hazey_Dazey
I have had the same issues, with the same medium and nutes, with autoflowers.
I was doing the same as you, half dosage etc. Same leaves, thought was Mag def, not N.
Tried CalMag tried Epsom Salts. Nothing.
I am now growing a photo, and decided to follow BioBizz's instructions. She's 6 weeks in flower and doing great! Maybe it really was N def, cus on the chart it says to give as much Grow as Bloom so...
This is my 2 cents:
Follow BioBizz official nutes chart for LightMix.
Water with 10% runoff ( as per BioBizz suggestion on their website ).
Add 1 teaspoon/liter of epsom salts ( magnesium sulfate ) to your watering once per week.
I really hope this helps, since I will go back growing autos when this photo finishes. I have very nice auto genetics and it would be a shame to make my plants suffer...
Keep us updated, best of luck brother
All good brother, definitely similar issue!
Yet there are so many threads like this one without conclusion
Very nice bro, I'm happy you fixed her
Sure thing. So, I have been phing my water since I first saw the issue (6.5) and checked the runoff each time, which fluctuated between 6 and 6.4, so I knew the nutrients were accessible, or at least they should be if there was no build up in the soil; this was my next step.
Wouldn't you want lower ppm coming out? Runoff ppm should be lower vs input ppm to signify the roots are taking in nutrients? I could be misunderstanding this but I was of the impression the roots eat so less should be running off.Sure thing. So, I have been phing my water since I first saw the issue (6.5) and checked the runoff each time, which fluctuated between 6 and 6.4, so I knew the nutrients were accessible, or at least they should be if there was no build up in the soil; this was my next step.
Now, too much of one nutrient can lock out others, so, even though I am running organic nutes, I did check my PPM going in, and PPM coming out; it was very similar, which is good. If the reading coming out is much higher, water with plain PH water until it comes back down. However, I am using organic nutrients so this is less relevant for me - this is a very important step if you're using synthetic nutes.
So, I came to the conclusion that I did not have lockout, and that my PH was in check, which meant, in my experience, that it could only be underfeeding. The issue was which nutrient. In my mind, there was no way that this was natural fade, and that has proven to be true, despite comments from some users earlier on.
I did originally think that it was an Mg issue, but as the issue progressed, the leaves displayed more symptoms of N and K deficiency mixed together (some completely yellow lower leaves, and some with burnt edges/tips). The intervein chlorosis didn't resemble Mg deficiency on some leaves when I look back on it (not enough green veins, and too much yellow); others it did look more prominent though (second in from bottom left in the image below). Hopefully you can see what I mean here with some of the ones I cleaned up. I don't think lack of Mg was the worst of it, and the increased CalMag doses seemed to iron it out (if that was the issue).
View attachment 4928792
I'm not an expert, but I have experience growing several crops other than weed, and this is just my best guess based on my experience
True, that's what got me fucking up my plants in the first runs. Thankfully threads like this exist.
You are correct, I was writing based on my organic nutes
I just wanted to make sure there wasn't a huge positive difference, which for me, was good enough.