First Grow - New Growth Yellowing?

[Moose8810]

Problem: Newer growth seems to be yellowing, looks like it starts at the tip and works its way to the stem. Serrated tips stay dark green. Some red stems, not sure if they're related or if the stem color is problematic. This appeared overnight, 24 hours ago they were all lush green (the leaves, stems have been red/purple the whole grow) and loving life.

Medium/grow method: Botanicare Coco/perlite 70/30 mix, 5 gal fabric pots.

Feed: and supplements used: GH trio and CalMag+ to 1.0 EC, SuperVit 1 drop/gal, 5.8-6.0pH up until last night. The issue showed up just before this, but tonight was the first time I switched to flowering nutes a friend recommended; Growth Technology Ionic Bloom, Buddha's Tree PK9/18 (1/4 suggested dose), Buddha's Tree Advanced Metaboost (also 1/4 suggested) to 1.1EC, 5.9pH.

Recharge used once or twice a week.

water source: Well water, 140ish ppm 6.8-7.0pH from the tap

Strain/age: Grower's Choice Seeds Gorilla Glue Auto, day 44 from sprout.

light used: 630w CMH (1x 3100K and 1x 4200K bulbs), 4x 3500K Autocobs, 2x 2700K Autocobs (5x5 tent, CMH in middle with Autocobs along the sides)

Climate: Lights on: leaf surface temp ~70F (75-79F ambient), ~50% RH. Lights off: mid 60s leaf surface temp (~72F ambient), 58-62% RH. Dehumidifier is on constant operation and the tent is fully ventilated, not much more I can do humidity wise unfortunately.

Additional info: Two other GG's adjacent to this on the same feed schedule are showing no signs of any issues, one is slightly larger and one slightly smaller. Older/lower growth looks perfect, for now. The only leaves that have this yellowing are near the top nodes.

I'm thinking my EC may be a little low, but I wanted to ask for advice and opinions before I burn the hell out of her. My gut tells me it's a deficiency of some sort, but I can't tell which after consulting all the charts I know of. Hoping I caught it early enough that it won't slow her down much.

Any input is greatly appreciated!

The plant in question is in the middle of the first picture.

 

[HandsomeJohnny]

Problem: Newer growth seems to be yellowing, looks like it starts at the tip and works its way to the stem. Serrated tips stay dark green. Some red stems, not sure if they're related or if the stem color is problematic. This appeared overnight, 24 hours ago they were all lush green and loving life.

Medium/grow method: Botanicare Coco/perlite 70/30 mix, 5 gal fabric pots.

Feed: and supplements used: GH trio and CalMag+ to 1.0 EC, SuperVit 1 drop/gal, 5.8-6.0pH up until last night. The issue showed up just before this, but tonight was the first time I switched to flowering nutes a friend recommended; Growth Technology Ionic Bloom, Buddha's Tree PK9/18 (1/4 suggested dose), Buddha's Tree Advanced Metaboost (also 1/4 suggested) to 1.1EC, 5.9pH.

Recharge used once or twice a week.

water source: Well water, 140ish ppm 6.8-7.0pH from the tap

Strain/age: Grower's Choice Seeds Gorilla Glue Auto, day 44 from sprout.

light used: 630w CMH (1x 3100K and 1x 4200K bulbs), 4x 3500K Autocobs, 2x 2700K Autocobs (5x5 tent, CMH in middle with Autocobs along the sides)

Climate: Lights on: leaf surface temp ~70F (75-79F ambient), ~50% RH. Lights off: mid 60s leaf surface temp (~72F ambient), 58-62% RH. Dehumidifier is on constant operation and the tent is fully ventilated, not much more I can do humidity wise unfortunately.

Additional info: Two other GG's adjacent to this on the same feed schedule are showing no signs of any issues, one is slightly larger and one slightly smaller. Older/lower growth looks perfect, for now. The only leaves that have this yellowing are near the top nodes.

I'm thinking my EC may be a little low, but I wanted to ask for advice and opinions before I burn the hell out of her. My gut tells me it's a deficiency of some sort, but I can't tell which after consulting all the charts I know of. Hoping I caught it early enough that it won't slow her down much.

Any input is greatly appreciated!

The plant in question is in the middle of the first picture.

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Looks similar to a nitrogen def. I had on my last batch of Gorilla photos. I'd suggest raising your EC either by dialling up your nutes or adding a little nitrogen isolate. If you've recently switched from grow to bloom nutes it may be that she's still looking for nitrogen during flowering stretch.

Good luck matey!

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[Moose8810]

Thanks for the info! I crawled under the netting last night, a couple of the lowest leaves way inside the plant are starting to yellow as well. Not sure if it's related and is an indication she's pulling nitrogen up, or if she's just disposing of them due to low light down low and it being a little later in her life.

I make sure I get plenty of runoff every feeding, for the hell of it I checked pH in the drip trays after watering last night a bit after I made this post. The other 5 plants' runoff were in the 5.8-6.2 range, this one was around 6.7. I ran a couple gallons of feed (on top of their normal watering) through it at 1.1 EC/5.6 pH, and her runoff is now 5.8.

Going to up my EC tonight and see how it goes.

If a little more nitrogen doesn't fix this, could it be a zinc deficiency caused by high pH in the coco? I initially thought it looked like maybe an iron or manganese deficiency but after more reading and the runoff pH @ 6.7 I'm wondering if it's more likely zinc getting locked out?

If it is, should I do anything beyond the mini flush I did last night? This morning she was looking great other than the color being off a bit like in the pics, she's praying hard.

 

[HandsomeJohnny]

Thanks for the info! I crawled under the netting last night, a couple of the lowest leaves way inside the plant are starting to yellow as well. Not sure if it's related and is an indication she's pulling nitrogen up, or if she's just disposing of them due to low light down low and it being a little later in her life.

I make sure I get plenty of runoff every feeding, for the hell of it I checked pH in the drip trays after watering last night a bit after I made this post. The other 5 plants' runoff were in the 5.8-6.2 range, this one was around 6.7. I ran a couple gallons of feed (on top of their normal watering) through it at 1.1 EC/5.6 pH, and her runoff is now 5.8.

Going to up my EC tonight and see how it goes.

If a little more nitrogen doesn't fix this, could it be a zinc deficiency caused by high pH in the coco? I initially thought it looked like maybe an iron or manganese deficiency but after more reading and the runoff pH @ 6.7 I'm wondering if it's more likely zinc getting locked out?

If it is, should I do anything beyond the mini flush I did last night? This morning she was looking great other than the color being off a bit like in the pics, she's praying hard.

The fact that it's starting from the bottom suggests nitrogen I think. I've never had a zinc def before, so I'm not sure, but I do know that when my current autos (gold glue/ chemdogging) were around day 45 I was feeding on a slightly higher EC (around 1.5-1.7) and mine have grown massive, solid colas (pics related). You can see that one of mine had a phosphorus def at one point and got a load of yellowing, but never stopped packing the weight on.

Mine are due to come down at the weekend [emoji41] cant wai!t
I'd suggest dialling up your EC, which I think will take care of any probs you're having.

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[Moose8810]

Your girls look great! Fingers crossed mine turn out as well.

I'm hoping upping the EC and dropping the pH runoff will take care of it. I don't think it started at the bottom, the 2 leaves that are yellowing down low look to be a natural fading. They're uniformly fading, stems and all. The leaves just above and opposite them (outward facing, yellowing is inside) on the same node are still lush green

 

[HandsomeJohnny]

Cheers dude. It's only my 2nd grow and my first doing autos / using coco / in a wilma autopot. I'm pretty proud of them [emoji4]

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[DABaracuss]

OK if your tip burn is form early in the grow I would say up your feed and I see you use cmh and led you make need to add like 1-2 tsp per gallon of cal/mag.She should start to finish up fast now and get some brown hairs ..I say 2and a half to 3 weeks left.

 

[HandsomeJohnny]

OK if your tip burn is form early in the grow I would say up your feed and I see you use cmh and led you make need to add like 1-2 tsp per gallon of cal/mag.She should start to finish up fast now and get some brown hairs ..I say 2and a half to 3 weeks left.

Yeah, forgot to mention I'm under 400w hps for this one, using canna coco a&b / rhizotonic / boost / cannazym / pk 13/14

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[Arthur]

Looks like a little potassium or phosphorus deficiency to me... and some beautiful nug....

The purple stems lean me toward potassium.

 

[Moose8810]

@Arthur @DABaracuss you're refering to HandsomeJohnny's plants, right?

I've upped my EC to 1.1 tonight, planning on creeping it up until I see improvement. What EC should I aim to top out at? I believe I'm at least 4-5 weeks from harvest, probably longer... how fast should I increase my EC? No noticeable changes between last night and now, she's still praying and still off-color