Issue with light intensity, hunger or both?

[resinbranch]

Bare with me folks - if you’re familiar with my

posting style by now you’ll know I type an essay haha.

 

Currently at day 23-24 flower. A bunch of branches that are closest to the light - centre to the 2x Telos 10s) are a paler shade of green than ideal. This has been ongoing over the last 2 & a bit weeks, where currently the tallest tops are sitting 40cm below the lights (set to 65% / c.340w).

 

Watering & feed habits are giving them 5.5L every 3 or so days, with a 7L drench with Biosys every 9 days. Using a mix of Life-Cycle dry amendment (which I forgot to top dress at start of flower but have done so day 20) & light dosages of Biobizz Grow / Bloom / CM (1ml of Grow, starting at 1ml of Bloom at week 2). When hitting them with the Biosys I use an ever lighter dose of BB (0.5-0.75ml Grow, 0.75-1ml Bloom). 
 

Highest light intensity reading at the tallest tops measures at around 950ppfd (DLI at around 38) when using the Photon app. When looking at the affected plants, the tops on the outer side of the lights a healthier shade of green - which leads me to suspect the issue is to do with light intensity, but maybe combined with hunger.

 

One thing I want to add is that during the first 2 weeks of flower I reduced temps to 25 & no more than 26c, equal to day & night to minimise stretch. RH was kept high so VPD was on the lower side of ideal (around 0.8). I’m thinking this probably will have affected uptake & in turn the amount of nutrition received. They may have slowed a touch in drinking, but for the most part don’t recall changing much to their watering schedule as mentioned above. 

 

The overall enviro is pretty much dialled in - or at least I’m happy enough with it. Root temps are 21-22c with an inkbird controller regulating it during lights off. Air temps are currently 27-28c. RH 62-65%, with VPD now sat at around 1 (I increased temps a touch last week, opting to gradually bring it & VPD back up over a week until the heavy defoliation on day 20). Additionally - I did opt to defoliate 2 handfuls of leaves a few times throughout the first 2 weeks. Nothing heavy, just where I felt it was needed to combat air flow / any moisture on leaves. This could have been additional stress as I’d only stripped them back a few days before flipping. Also - I missed a watering in the first week by a day & that resulted in them all dropping. Nothing extreme but still a stress due to under watering. 
 

couple photos for reference - two of closer shots of the plants, one showing the lighter green on the more centred tops in the canopy & the other on the outer side that looks healthier. 

 

I’ve planned a heavier feed tonight with the biobizz, before backing off to a lighter dose as the dry amendment should start to kick in around Saturday (a week after top dress & watering in with Biosys). 
 

 

 

 

 

[MySoulIsMine]

what size pots are they in? They look fine to me but I would drop that 7l drench as that will be likely overwatering. Just follow a basic wet and dry cycle and start them on a proper feed schedule 3ml /l every watering and go from there. No need to overcomplicate it imo  

[resinbranch]

Another point to ask actually - as I can’t raise the lights any more & I’m stuck at leaving them at around 340w to keep ppfd in the adviseable margin without co2 supplementation, would switching light schedule to 11/13 be a negative in any sense? I’m kicking myself for not chopping them down shorter in order to keep height down that little bit more - 20cm or so shorter would allow me to run the lights at 100% (c.580w) & maximise coverage / yield. Ffs haha 
 

Anyway, I’m thinking that it’ll allow a higher light intensity while still keeping the DLI within the 40 range. It’s all gonna get frozen & washed for hash in the end, so the resin is my focus - i may well be wrong in my understanding / speculative reasoning but would giving them a higher light intensity with an hour darkness help with resin production? 

[resinbranch]

Just now, MySoulIsMine said:

what size pots are they in? They look fine to me but I would drop that 7l drench as that will be likely overwatering. Just follow a basic wet and dry cycle and start them on a proper feed schedule 3ml /l every watering and go from there. No need to overcomplicate it imo  

After all that I typed I forgot pot sizes haha….they’re in 22L fabrics

 

The 7L drench equates to 32% volume of pot size, which is within the range for a rooted out pot afaik - though I should have noted that I don’t do it all in one. 5L is given on the day they’re due to be watered (3L watered slowly with a water sprayer, 2L drenched in 500ml increments). Then the additional 2L is done again with 500ml jugs the next day. Once every 9 or so days, mainly just to try & ensure there’s no dry patches in the soil. Any run off in the tray is small & quickly soaked back up too, if that helps for reference.
 

No signs of overwatering from what I’ve observed but I hear what you more saying - better to air on the lighter side than be too heavy.

[KC]

29 minutes ago, resinbranch said:

I did opt to defoliate 2 handfuls of leaves a few times throughout the first 2 weeks. Nothing heavy

 

To me it looks like there is barely anything left on there  The way I look at it is plants need leaf matter, that's how they photosynthesise. It's common to take out the low parts as they don't get much light and it's a PITA having to harvest airbuds, it's just not worth the effort for what you get back.

 

I'd be inclined to think the tops don't like the amount of light they are receiving, you can supercrop them to get them away from the light a bit. Depending on how flexible they are the moment you might not even have to crush the stem, you can just use garden wire to pull the tops down and tie them to somewhere lower down on the plant. 

[resinbranch]

36 minutes ago, KC said:

 

To me it looks like there is barely anything left on there  The way I look at it is plants need leaf matter, that's how they photosynthesise. It's common to take out the low parts as they don't get much light and it's a PITA having to harvest airbuds, it's just not worth the effort for what you get back.

 

I'd be inclined to think the tops don't like the amount of light they are receiving, you can supercrop them to get them away from the light a bit. Depending on how flexible they are the moment you might not even have to crush the stem, you can just use garden wire to pull the tops down and tie them to somewhere lower down on the plant. 

yeah, while I intended to strip the lowers below the trellis & lollipop above it I admittedly went heavier than i planned when it came to the heavy strip back on day 20. I’ve seen plants stripped in the same way that bounce back well, so treating this as an experiment of sorts….though I guess to do so with the entire crop is risky with any experiment. 
 

I’m inclined to agree with you about the paleness of the taller tops - it started to happen prior to reaching the closeness to the lights, but it was my first thought (with potential increase in appetite to compensate the high ppfd being secondary).
 

Will take a look at tying some down but i fear the taller tops will lean into the neighbouring branches, so a hard style supercrop may be the better option (ideally don’t want to do so but when needs just & all that).

 

appreciate your insight dude, thanks again 

 

 

Edited February 28, 2023 by resinbranch