Are these plants hungry?

[olegren]

I need to have my head examined for trying coco out at such an early point in my career. I was always intrigued with the medium and its place between the extremes of hydro and soil. Once I ended up with a set of autopots, I thought it would be easy. I made it a point not to say that aloud, but thinking it alone must've been enough to jinx this thing.

Problem: Seeing all kinds of leaf issues which have slowly but surely intensified over the last two weeks. I see mobile and immobile issues all over. I'm not sure if it's deficiency or toxicity; but leaning towards the former. Lots of yellowing up top. Bottom leaves are being cannibalized. Rust spots throughout; with the best color in both plants sitting somewhere in the middle. Both of these plants have had a bit of a taco to them (Strawberry more than Grape) for much longer. I have been extremely cautious with my lights and do not think it's related to them.



Medium/grow method: Mother Earth coco bale. Hydrated, rinsed, and double buffered. Mixed 70% to 30% espoma perilite.

Feed: and supplements used: Prescription Blend nutrients with no other supplements. Currently feeding at half vendor recommended dose for week 3 of flowering -- to the tune of 500ppm.

water source: RO (Well water run through home system) fed via autopots.

Strain/age: Mephisto Double Grape & Strawberry Nuggets. Today is day 49.

light used: HLG QB V1 (260W) - 3000K. She's dimmed somewhat. Tops of plants are sitting around 53.5K lux which is 780ppfd by vendor recs. For what it's worth, I have not raised intensity in 2 weeks; wanted to see how much they'd stretch.

Climate: Last week's average temps & RH: 77.3F & 49.2%

Additional info: Some additional background which is scattered across a few other infirmary posts.

I have conservatively fed these gals all along, but I was still worried about toxicity. (Some tips did look burnt for a while; although I never had clawing or the darker green color associated with excess nitrogen) 10 days ago, I had the bright idea to check pH in my coco with Accurate 8 and found a high reading in both. The grape pot was sitting around 6.5 while the Strawberry was more like 6.8. Res and tray both read same values: 6.0 and ~350 ppm. I opted to do a flush.

I flushed with a 300ppm mix: Nutes + GH calmag. (150ppm each) Ran 10 gallons through each plant. From the first gallon to the last, I was getting consistently the same pH out as was going in; and ppm were less (~250 on average). Great, right? So they're just hungry. I figured between the pH problem (Still not sure of root cause) and the fact that they were taking up so much, I needed to ramp things up. Gave them a feeding and set them back up on the reservoir. Upped feed to about 500ppm.

In the time since, I've been trying to keep my hands off of them. No additional supplements. No additional tweaks. Feeding at roughly the same strength; although the symptoms continue to get worse. I've heard so many people say 500ppm is the ceiling for autoflowers, but this still looks a lot like they're just hungry.

What do you experts think? Should I just ramp the feed up a bit more? Prescription Blend does recommend 1000ppm (1.0EC) at their full dose schedule, and the instructions mention autoflowers. I'm leaning towards giving them around 600 ppm to see if it has any effect. I'm checking pH in medium for both, and it's still in the sweet spot -- getting readings from 5.8 to 6.3. Been letting the pH in res/trays vary a little; as low as 5.8 and as high as 6.2. Doesn't seem to be having a large effect.

Thank you, as always, for your insights and wisdom.

 

[Simplicio]

Careful with LEDs.
Light burn is easily possible.
I think that's what you have.
If those were my plants I'd lower light to about 20 kLux, and reduce feed to about 400 ppm.

Too much light cause all kinds of hard to diagnose problems.
I start getting trouble above 25 kLux.

Little will be lost from raising lights, and it might help fix things.

 

[DCLXVI]

I'd love to help but I've got no idea on coco. Just a thought......I think from what I have read, your ph is on the high side? In coco it should keep between 5.5 and 6.5 so maybe keep it in that 5.5 - 5.8 range a few days and see if they recover?

I'm intrigued by it as well and have been doing my homework but no hands on experience so don't listen to me, I could be way wrong. I'm sure the pros can pick out a problem spot for ya soon.

 

[olegren]

Thank you both for weighing in!

@Simplicio - I was very concerned about light burn myself since I bought this light. For what it’s worth, I last adjusted at 33k — and they’ve grown into it since. Currently at 17” above and no real way to raise them further. I certainly could dim; but am having trouble aligning to light burn symptoms. Some leaves up top look good while others are rough — but then the lower yellowing/necrosis suggests mobile nutrient issues. Can you help me to understand the light burn symptoms you’re noticing? I do appreciate it.

@DCLXVI - thanks. I’m trying to do better with letting pH swing a bit. I had thought 5.8-6.3 or so was the sweet spot (higher for flower) but could be mistaken. Gonna read some more about this!

 

[Mañ'O'Green]

light used: HLG QB V1 (260W) - 3000K. She's dimmed somewhat. Tops of plants are sitting around 53.5K lux which is 780ppfd by vendor recs. For what it's worth, I have not raised intensity in 2 weeks; wanted to see how much they'd stretch.

Climate: Last week's average temps & RH: 77.3F & 49.2%

I flushed with a 300ppm mix: Nutes + GH calmag. (150ppm each) Ran 10 gallons through each plant. From the first gallon to the last, I was getting consistently the same pH out as was going in; and ppm were less (~250 on average). Great, right? So they're just hungry. I figured between the pH problem (Still not sure of root cause) and the fact that they were taking up so much, I needed to ramp things up. Gave them a feeding and set them back up on the reservoir. Upped feed to about 500ppm.

What do you experts think? Should I just ramp the feed up a bit more? Prescription Blend does recommend 1000ppm (1.0EC) at their full dose schedule, and the instructions mention autoflowers. I'm leaning towards giving them around 600 ppm to see if it has any effect. I'm checking pH in medium for both, and it's still in the sweet spot -- getting readings from 5.8 to 6.3. Been letting the pH in res/trays vary a little; as low as 5.8 and as high as 6.2. Doesn't seem to be having a large effect.

Thank you, as always, for your insights and wisdom.

I believe this is the source of your problem (highlighted in red) This is way out of balance with much too much Cal-mag in relation to the other elements. The damage was done then.

1.0 EC is 500PPM on the Hanna scale. I take autos up to ~ 700PPM of nutrients not counting my starting water. That is sometimes too much for some strains and others like even more. I start autos at about 50% of the vendor chart strength and up it 10% each week until I get a little bit of tip burn and then back off 10%. This gets me to the level that plant likes. It is a bitch when two plants running on the same reservoir have way different likes.

 

[Olderfart]

I need to have my head examined for trying coco out at such an early point in my career. I was always intrigued with the medium and its place between the extremes of hydro and soil. Once I ended up with a set of autopots, I thought it would be easy. I made it a point not to say that aloud, but thinking it alone must've been enough to jinx this thing.

Problem: Seeing all kinds of leaf issues which have slowly but surely intensified over the last two weeks. I see mobile and immobile issues all over. I'm not sure if it's deficiency or toxicity; but leaning towards the former. Lots of yellowing up top. Bottom leaves are being cannibalized. Rust spots throughout; with the best color in both plants sitting somewhere in the middle. Both of these plants have had a bit of a taco to them (Strawberry more than Grape) for much longer. I have been extremely cautious with my lights and do not think it's related to them.

View attachment 1274098 View attachment 1274099 View attachment 1274100 View attachment 1274102 View attachment 1274103 View attachment 1274104 View attachment 1274105 View attachment 1274106

Medium/grow method: Mother Earth coco bale. Hydrated, rinsed, and double buffered. Mixed 70% to 30% espoma perilite.

Feed: and supplements used: Prescription Blend nutrients with no other supplements. Currently feeding at half vendor recommended dose for week 3 of flowering -- to the tune of 500ppm.

water source: RO (Well water run through home system) fed via autopots.

Strain/age: Mephisto Double Grape & Strawberry Nuggets. Today is day 49.

light used: HLG QB V1 (260W) - 3000K. She's dimmed somewhat. Tops of plants are sitting around 53.5K lux which is 780ppfd by vendor recs. For what it's worth, I have not raised intensity in 2 weeks; wanted to see how much they'd stretch.

Climate: Last week's average temps & RH: 77.3F & 49.2%

Additional info: Some additional background which is scattered across a few other infirmary posts.

I have conservatively fed these gals all along, but I was still worried about toxicity. (Some tips did look burnt for a while; although I never had clawing or the darker green color associated with excess nitrogen) 10 days ago, I had the bright idea to check pH in my coco with Accurate 8 and found a high reading in both. The grape pot was sitting around 6.5 while the Strawberry was more like 6.8. Res and tray both read same values: 6.0 and ~350 ppm. I opted to do a flush.

I flushed with a 300ppm mix: Nutes + GH calmag. (150ppm each) Ran 10 gallons through each plant. From the first gallon to the last, I was getting consistently the same pH out as was going in; and ppm were less (~250 on average). Great, right? So they're just hungry. I figured between the pH problem (Still not sure of root cause) and the fact that they were taking up so much, I needed to ramp things up. Gave them a feeding and set them back up on the reservoir. Upped feed to about 500ppm.

In the time since, I've been trying to keep my hands off of them. No additional supplements. No additional tweaks. Feeding at roughly the same strength; although the symptoms continue to get worse. I've heard so many people say 500ppm is the ceiling for autoflowers, but this still looks a lot like they're just hungry.

What do you experts think? Should I just ramp the feed up a bit more? Prescription Blend does recommend 1000ppm (1.0EC) at their full dose schedule, and the instructions mention autoflowers. I'm leaning towards giving them around 600 ppm to see if it has any effect. I'm checking pH in medium for both, and it's still in the sweet spot -- getting readings from 5.8 to 6.3. Been letting the pH in res/trays vary a little; as low as 5.8 and as high as 6.2. Doesn't seem to be having a large effect.

Thank you, as always, for your insights and wisdom.

FWIW, my two problem plants look the same. At this point, I have concluded that I have been starving them. I am am increasing the EC, currently at ~1200, and likely to go higher. Now just mega crop with a bit of extra phosphorus.

I may, however, be wrong, in which case, my grow is doomed.

Good luck with getting things sorted. Whatever you do, make a decision and act, if my experience is any indication, things could go downhill rapidly from here.

 

[Simplicio]

Thank you both for weighing in!

@Simplicio - I was very concerned about light burn myself since I bought this light. For what it’s worth, I last adjusted at 33k — and they’ve grown into it since. Currently at 17” above and no real way to raise them further. I certainly could dim; but am having trouble aligning to light burn symptoms. Some leaves up top look good while others are rough — but then the lower yellowing/necrosis suggests mobile nutrient issues. Can you help me to understand the light burn symptoms you’re noticing? I do appreciate it.

@DCLXVI - thanks. I’m trying to do better with letting pH swing a bit. I had thought 5.8-6.3 or so was the sweet spot (higher for flower) but could be mistaken. Gonna read some more about this!

My plants are happiest with much less food and light than most people use.
But I also follow the VPD chart, which might be partly responsible.
I've been trying a new strategy of giving sprouts more food and light sooner, and got some bleaching, which I decided couldn't be due to underfeeding (but maybe over-feeding?)
Some plants were stressing under 25 kLux from Rspec LEDs.
30 inches is my default light distance, and getting much closer than that causes leaf problems during mid-late flower.

 

[Creature]

Feed: and supplements used: Prescription Blend nutrients with no other supplements.
water source: RO
I flushed with a 300ppm mix: Nutes + GH calmag. (150ppm each)

Have you been adding calmag to your RO water before adding nutrients? If not, there's the beginning of your issues. You need to feed both the plant and the coco.

This isn't your typical "NeEdS CaLmAg", we're talking coco.

 

[Proph]

I remember seeing these same type of issues when we did the product testing for rx blend. I can't remember for sure but I think @Waira tinkered around with it a bit and may be able to suggest a proper dosage. I think certain products worked well, but all together things went haywire.. Very similar to mega crop.. I honestly think the ratios are out of balance for both product lines. It's hard to say what which product may be causing the issue when there are multiple products in use. I think rx blend is like 6 different bottles.

The other thing I have questions about is the "double buffered" thing.. Usually buffers are added in at the lab/facility where the coco was made, and then tested... Did you double buffer it yourself? And if so, with what and how much? Most companies buffer using calcium. That way you don't need to add "calmag" to coco like most of the newer growers believe.. So depending on how the buffer was done, that could be a major cause of what you are seeing as well..

 

[olegren]

Overwhelmed by the plethora of helpful responses. Thank you all!

@Mañ'O'Green - Thank you for sharing these. I am going to start using EC going forward since it seems a bit more universal. Regardless, I take your point: Some plants can handle more than others. I really like your approach of starting at half (I started at 25%; which caused some deficiency issues early on. Thankfully the plant recovered quickly as I increased) and then incrementing by small amounts until you notice hints of burn.

Regarding the flush solution: I agree. The ratio seemed strange to me. I'm trying to find the thread where I read it. Waira had recommended it to someone with a flush in coco. I assumed part of it had to do with the inherent issues of 'charging' coco, but it's science I still don't understand -- so I can only speculate. It's also very possible that I took the suggestion out of context; or that there were other reasons for the recommendation which applied to that user's situation but not mine.

@Olderfart - Been stalking your thread since you mentioned it in mine. I agree: Looks like the same kinds of issues to me. Since I have incremented feeding since the first flush, I may do another today just to see how runoff looks; and then pull the trigger on a feed adjust. I did see tip burn early on in both of these plants, and combined with the taco effect that was there virtually all along, I have to wonder if something isn't out of whack. My last increment of food (from 300 to 450) didn't seem to touch it, so I am skeptical but hopeful that it will solve for me. Gonna keep an eye on yours as well. I hope it goes well!

@Creature - Nope. No calmag added. The vendor mentions that calmag is a part of the solution already. They say that you can add cal mag for plants that require more, but I had done this in previous grows and ran into toxicity/uptake problems that I ended up attributing to upsetting the balance in their formula.

@Simplicio - I have seen a lot of cautionary tales on LEDs and will keep this in mind -- Thank you. I'm in a 2x4x6, so I keep my lights at max height and toggle dimness. I usually land on 20k around the time veg is really picking up. I tend to tweak 2-3K at a time and watch closely for any new issues. I want to experiment with lower lux settings to encourage more stretch and get a bit more elaborate with LST, so I'm going to try your threshold in a future grow.

@Proph - I saw hints of something similar in another user's PB grow. Just not sure. You're right in that Rx blend is 6 different bottles. They're meant to be mixed in a specific order, and I try to be very precise in measurements to make sure I am giving exactly what they describe. (Difficult lesson learned early on. Mixing out of order produces this crazy sludge) My process is typically to mix full batches by the gallon; and then mix to pure RO in the res in order to hit my target ppms. Then I will pH if necessary. Vendor mentions it should land at 5.8-6.3, but I am seeing much closer to 5.3-5.5.

Regarding buffering: This was done by me unfortunately. I wanted to find evidence that the vendor had done it. Mother Earth mentions that they buffer their bagged coco mix product, but I couldn't find any similar statement for their 5kg coco bale; which is the only thing my local hydro shop had on hand. (It was the middle of pandemic shortages last summer) If I had it to do over, I would've just gotten a canna brick from Amazon. I can't even find the brick on their website anymore, so I'm wondering if they discontinued it.

All that to say: I did a 2x dose of my GH calmag (7.5ml/gal) to RO water and let it soak twice for about 8 hours each session. I rinsed after the first buffer session but did not after the second. I think this might've been part of my pH problem early on. I was running with a random video I found. The subtle taco I noticed in both plants (but moreso the Strawberry) does make me wonder if there wasn't a balance issue all along that exacerbated when she moved into flower and requirements shifted.