New leaves are turning yellow from the centre (After LST and watering)

[supersecretusername]

Hi all,

So this is my first grow and so far its been going alright. Currently on the 4-5th week of Veg, and this is a stardawg autoflower. I am growing in coco, using general hydrophonics nutes and aim for a PH of about 5.8 - 6.

Basically two days ago I decided to LST my plants (which I think I should have started earlier) and start to train it. This involved removing a couple of fan leaves that were either blocking light or being blocked and bending the branches slightly. I fed them start away and upped their nutes by about 15%.

Yesterday they looked to be growing nicely (well one had shown slow growth compared to the others but was still looking good) but today after looking at them I have noticed that they have suddenly developed light/green yellow colours around the new growths.

Seemingly, this colour is starting from the very centre of the new leaves. This is very clear on two of them, with one of them having only a slight discoloration at the moment on some of the leaves. Admittedly, I didn't water my plants yesterday as I have been concerned of over watering them and giving time for the medium to dry slightly, (I used to water everyday as advise I saw online to do this with coco, but i saw signs of overwatering and some pieces of perlite started turning green so I assumed that Algae was growing indicating overwatering).

One thing I should probably own up to, is that as we had nice weather earlier this week i decided to take my plants out to see the sunlight for a couple hours to help growth two days this week. They weren't in contact with the sun for more than 3/4 hours at a time. I did this as I cheaped out and bought a really shit 1000W LED (110 actual watts if that) and currently waiting my new LED's to arrive next week.

I have fed by plants tonight but with a really dose of nutes.

So my questions:

1. I was wondering if anyone has had any issues like this? My assumption is that this is likely a nutrient issue and I just went overboard (was like 880PPM on TDC reader). However I was wondering if it could also point to under or over watering, or putting them by the sun.
2. What would be the best way of getting my plants back to health?
3. How will this affect future growth / end result possibly?


Thanks all again!

Here are the photos of all three plants, the last photo is the plant with the slow growth and minimal affects as of yet. First two pictures have flash on and rest is nature lighting:

[supersecretusername]

Okay I think I know how I fucked up. I think this is actually a sign of nitrogen and/or iron deficiency due to the LST and slight overdose in feed.

As I removed a couple fan leaves the plant lost some of its stored nutrients, and as my ec was to high the water was to salty for the nutrients to be observed by my the plants properly.

Fed it quarter nutes tonight and will then continue feed it properly (right PPM this time) from next watering. Will probably water with quarter or half nutes every other watering to avoid a salt build up.

Though I would be wrong...

[scoobywho]

Okay I think I know how I fucked up. I think this is actually a sign of nitrogen and/or iron deficiency due to the LST and slight overdose in feed.

As I removed a couple fan leaves the plant lost some of its stored nutrients, and as my ec was to high the water was to salty for the nutrients to be observed by my the plants properly.

Fed it quarter nutes tonight and will then continue feed it properly (right PPM this time) from next watering. Will probably water with quarter or half nutes every other watering to avoid a salt build up.

Though I would be wrong...

Think your on the money with iron def mate, nitrogen def usually starts at the bottom of the plant and works from the leaf margins in in my experience.

Do you have an iron supplement in your feed it sometimes comes additionally in cal/mag additives.

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[scoobywho]

Okay I think I know how I fucked up. I think this is actually a sign of nitrogen and/or iron deficiency due to the LST and slight overdose in feed.

As I removed a couple fan leaves the plant lost some of its stored nutrients, and as my ec was to high the water was to salty for the nutrients to be observed by my the plants properly.

Fed it quarter nutes tonight and will then continue feed it properly (right PPM this time) from next watering. Will probably water with quarter or half nutes every other watering to avoid a salt build up.

Though I would be wrong...

Also dont fluctuate your EC mate the plant uses energy to adjust the root sugars to uptake water so if its constantly jumping from quarter to half strength then back to quarter it makes hardwork for them. You just need to find that sweet spot and raise the strength when you see her getting lighter in colour. It's a hard skill I'm still learning Haha.

You should be watering to 20% runoff every watering, that should stop salt buildup can even do a mini flush going into flower if you want to be safe but usually not needed imo.

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[RASTA]

I agree with scoobywho here. Its deffo an iron deff.
These plants do not even need loads of iron. And if yer using yer tap water....it should have well enough traces of it to satisfy its iron needs. So....unless your using RO water, make sure your ph pen is calibrated properly. Iron deffs in coco would happen if your ph is too high. So if pens calibrated n your giving feed ph'd at 5.8-6 like you say....then it could well be an issue with over watering. But overall look of em dont look like they over watered. I would actually be tempted to feed them every day now in coco. Ph'd at 5.8

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[supersecretusername]

Thanks guys alot for the feedback. I didnt realise that I was messing about with the plant by altering PPM all the time so will keep it consistent.

The thing is I literally calibrated my PH pen last week, so it should be accurate unless I somehow did it wrong which I doubt.

The yellowing doesn't seem to have spread since watering for the last two days and around 5.8-6 and a consistent PPM of around 600.

I checked the runoff PH which shows to be around 6.20-6.30 for each plant. However checking runoff ppm I noticed two or my plants had a PPM that was around 100-150 higher?

Should I be concerned with this?

Keeping a watchful eye hoping my girls will turn back to a nice green and as said it seems to stop spreading now so hopefully it's good news.