Photoperiod Gorilla Glue #4 & White Widow

[tronN00dles]

I haven't done a "stats" update in a while. Here are the state of things today, just exiting the pre-flower/transition stage:

VPD Target: 1.0 - 1.2

• RH bandwidth: 51% - 54%
• Temp bandwidth: 23.5C - 25C (ambient)

Lighting Info:

• DLI Upper Limit: 28
• PPFD Upper Limit: 645
• Cycle: 12/12
• Eq. to 41,600 lux based on HLG-specific conversion calculator
• Power Draw: 230W (ac)

Nutrient Solution:

• Targeting 645ppm inc. 70ppm starting water
• Recipe for "early bloom" is a custom formula based on the latest GH Flora 10-part "aggressive" mix scaled to 45%, except for CalMag, which is maintained @ 2.5mL/gal (prior to now, Cal-Mag had been kept at ~3.2 - 4.0 mL/gal for the second half of veg)
• I maintain an Excel workbook that compares the N-P-K-Ca-Mg-S levels in various popular GH feedcharts, including the original Drain-to-Waste recipe; the latest light/medium/aggressive recipes, the CocoTek recipe, and the CocoForCannabis recipe. I'm playing around with some custom formulas based on those. The CocoForCannabis recipe is excellent and has a lot of "smarts" about it, but it lacks the organics (FL+) that I'm trying to incorporate. I'll probably make a more detailed post about my observations in the near future. I'm essentially trying to recreate the CocoTek feedchart, using CocoForCannabis ppm's, out of Flora Series ingredients lol. Stay tuned....
• pH target 5.7-6.3, usually around 5.9. This range will get a little tighter as flowering progresses.

Fertigation Technique:

• Watering with nutrients 5 times per day, to 10-20% run-off.
• A few times per week I'll supplement the automatic fertigation with "hand watering". I do this to ensure there are no dryspots - I'm skeptical of the hydro halos.
• I try to maintain run-off EC to be within 150ppm of my intake. This is very much an active process. I'm thinking once per week I will have to do some sort of "EC mitigation", which usually involves increasing the volume and reducing EC for one event to do a sort of mini-flush.

If you haven't guessed already, I'm a fan of control systems... I Intend to gradually increase DLI/PPFD, nutrient EC/ppm, and VPD in the coming weeks. Slow and steady is the game this time around.

tron

 

[Delps8]

Why a DLI of 28?

 

[tronN00dles]

Why a DLI of 28?

I've been playing around with DLI targets on the past few grows to see what works best for me. Historically, I've had 3 DLI/PPFD targets depending on auto or photo: (1) for seedlings; (2) for veg; and (3) for flower. This time around, I'm trying something like this: https://growlightmeter.com/lighting-requirements-of-cannabis-over-the-full-grow-cycle/. I'll bump it up to 30 next week, and keep increasing weekly and peak around 40. I should clarify I'd actually target higher DLI's for flowering autos, but that's another story

Compared to previous grows, this is a much less drastic change in light intensity between late veg and early/mid flower. In the past, I've jumped up to closer to 750-800 PPFD by now, but I always noticed I'd get some signs of stress. This time around, I'm treating my VPD/DLI/nutrient EC as sort of a harmonious unit that will be gradually increased over the course of flower. We'll see how it goes lol. So far so good though!

 

[Delps8]

I've been playing around with DLI targets on the past few grows to see what works best. Historically, I've had 3 DLI/PPFD targets: (1) for seedlings; (2) for veg; and (3) for flower. This time around, I'm trying something like this: https://growlightmeter.com/lighting-requirements-of-cannabis-over-the-full-grow-cycle/. I'll bump it up to 30 next week, and keep increasing weekly and peak around 40. I should clarify I'd actually target higher DLI's for flowering autos, but that's another story

Compared to previous grows, this is a much slower transition between late veg and early flower. In the past, I've jumped up to closer to 750-800 PPFD by now, but I always noticed I'd get some signs of stress. This time around, I'm treating my VPD/DLI/nutrient EC as sort of a harmonious unit that will gradually be increased over the course of flower lol. We'll see how it goes. So far so good though!

Thank you for posting that link. I haven't been to their web site in some time and I see that it's been updated. I'll spend some quality time checking it out.

I've used the predecessor to that chart as a guide for DLI in seedlings and veg because it comports with a lot of other sources but I haven't found anything that shows the DLI drop in early flower. In contrast to what they're showing, Bugbee and Chandra, to name a few, don't discuss anything but continuous light levels. Have you run across research that backs up what Photone is recommending? I traded email with the programmer last year — I'll send him an email.

You added this - "I'll bump it up to 30 next week, and keep increasing weekly and peak around 40. I should clarify I'd actually target higher DLI's for flowering autos, but that's another story "

Ah, there's a story there! Do tell - my current grow is two G autos. They're younger than your photos (40 days above ground) but they're heading into flower RSN so I'd appreciate your insights. I'll check your early grow journals but if you have a few pearls of wisdom that aren't documented, I'm all ears.

CO2 is the limiting factor for photos. Have you considered doing DIY CO2? The "yeast in a bottle" approach seems dead easy. I just set on up today, in fact.

 

[Death The Cultivator]

Fertigation Technique:
Watering with nutrients 5 times per day, to 10-20% run-off.
A few times per week I'll supplement the automatic fertigation with "hand watering". I do this to ensure there are no dryspots - I'm skeptical of the hydro halos.
I try to maintain run-off EC to be within 150ppm of my intake. This is very much an active process. I'm thinking once per week I will have to do some sort of "EC mitigation", which usually involves increasing the volume and reducing EC for one event to do a sort of mini-flush.

I started vegging at 20DLI for 24/0 after growing monster mothers at work. We didn't ramp up the light intensity in flower like many sites suggest but went straight to 45-50 dli with c02.

The fertigation was something I didn't understand until I was able to fully speak with a horticulturist about Coco and fertigation. Technically, multiple irrigations per day vs one per day give the same results. I like the plan though because hand watering is sometimes necessary either to catch a day between watering events or to do drenches.

I think EC runoff is an irrelevant metric. If your input is always correct, the output doesn't matter and is there is an issue then it's corrected using the correct input through a flush. How do you check your runoff? An high volume flush with a lower EC isn't really necessary, rather your earlier plan of doing some hand watering during the week is perfect.

Your plants, not trying to criticize you or anything. If you wanted a valid method of measurement Bluelab METPULSE Pulse Meter Water 3-in-1 Moisture/Nutrient (TDS)/Temperature Test Kit for Garden Soil, Coco, and Solution, Ester for Hydroponic System and Indoor Plant Grow, Clear Amazon product

That would tell you the story you want right at the root zone otherwise you could distilled or RO water through a pot, collect the runoff and measure that.

 

[Delps8]

Thank you for posting that link. I haven't been to their web site in some time and I see that it's been updated. I'll spend some quality time checking it out.

I've used the predecessor to that chart as a guide for DLI in seedlings and veg because it comports with a lot of other sources but I haven't found anything that shows the DLI drop in early flower. In contrast to what they're showing, Bugbee and Chandra, to name a few, don't discuss anything but continuous light levels. Have you run across research that backs up what Photone is recommending? I traded email with the programmer last year — I'll send him an email.

You added this - "I'll bump it up to 30 next week, and keep increasing weekly and peak around 40. I should clarify I'd actually target higher DLI's for flowering autos, but that's another story "

Ah, there's a story there! Do tell - my current grow is two G autos. They're younger than your photos (40 days above ground) but they're heading into flower RSN so I'd appreciate your insights. I'll check your early grow journals but if you have a few pearls of wisdom that aren't documented, I'm all ears.

CO2 is the limiting factor for photos. Have you considered doing DIY CO2? The "yeast in a bottle" approach seems dead easy. I just set on up today, in fact.

That's a great resource. It should be posted somewhere prominent…er…ah prominently (stoned am I?).

 

[tronN00dles]

Thank you for posting that link. I haven't been to their web site in some time and I see that it's been updated. I'll spend some quality time checking it out.

I've used the predecessor to that chart as a guide for DLI in seedlings and veg because it comports with a lot of other sources but I haven't found anything that shows the DLI drop in early flower. In contrast to what they're showing, Bugbee and Chandra, to name a few, don't discuss anything but continuous light levels. Have you run across research that backs up what Photone is recommending? I traded email with the programmer last year — I'll send him an email.

You added this - "I'll bump it up to 30 next week, and keep increasing weekly and peak around 40. I should clarify I'd actually target higher DLI's for flowering autos, but that's another story "

Ah, there's a story there! Do tell - my current grow is two G autos. They're younger than your photos (40 days above ground) but they're heading into flower RSN so I'd appreciate your insights. I'll check your early grow journals but if you have a few pearls of wisdom that aren't documented, I'm all ears.

CO2 is the limiting factor for photos. Have you considered doing DIY CO2? The "yeast in a bottle" approach seems dead easy. I just set on up today, in fact.

Disclaimer: I'm no lighting expert, so take the following with a grain of salt. There's so much conflicting information out there, my strategy has been pretty much to read as much as I can, then try out a few different things and go from there.

As for the DLI drop in early flower, I suspect this is just a consequence of going from 18/6 to 12/12. If your PPFD stays the same during that transition, you'll have a drop in DLI. And no, I haven't come across any research about Photone's graph, aside from their note that it's based on their own 'personal experience'.

A quick aside, even though the graph shows increasing DLI and hence PPFD gradually throughout flower, I suspect that's largely a consequence of the plant growing taller and closer to the light. Right now, I can probably leave my light at ~230W, currently getting a PPFD of 645 or so. But the plant is growing taller by the day. I bet if I leave my light height/intensity where it is, and as the canopy grows taller, by the end of the stretch period I might be in line with those DLI targets on the chart for mid flower.

As for why I believe autos can tolerate higher DLIs... again, no expert, but here's a hypothesis... the rate of photosynthesis is directly proportional to PPFD, but there is an upper limit to what plants can tolerate. The range is debatable, but without CO2, you'll see a number like 800 PPFD thrown around a lot. Photoperiods and their 12 hour light period are still bound by this ~800 PPFD limit, which at 12 hours is a DLI of ~35.
Since autoflowers can flower with lesser dark periods, this opens up the potential for higher DLIs. The plant cells are still bound by the ~800 PPFD limit (presumably!), but now 800 PPFD at 18/6 becomes 52 DLI.

Long story short, I think my fundamental philosophy when it comes to lighting is to consider the generally accepted "ranges", then take measurements across the full canopy, and adjust lights so that nothing falls outside of those ranges. I've also come to respect the notion that the effects of lighting intensity "plateaus" or "saturates", and it's probably more important to ensure everything is surpassing the lower end of the range, rather than aiming for the higher end of the range, if that makes sense.

As for CO2, I've tried one of those plastic soda-bottle style jobbies. It seemed to help out a bit but I never bothered to try again. I think I can eventually grow enough without CO2 to sustain myself, so the next "project" of sorts is UV supplementation in flower. We'll see how that goes.

tron

 

[tronN00dles]

I started vegging at 20DLI for 24/0 after growing monster mothers at work. We didn't ramp up the light intensity in flower like many sites suggest but went straight to 45-50 dli with c02.

The fertigation was something I didn't understand until I was able to fully speak with a horticulturist about Coco and fertigation. Technically, multiple irrigations per day vs one per day give the same results. I like the plan though because hand watering is sometimes necessary either to catch a day between watering events or to do drenches.

I think EC runoff is an irrelevant metric. If your input is always correct, the output doesn't matter and is there is an issue then it's corrected using the correct input through a flush. How do you check your runoff? An high volume flush with a lower EC isn't really necessary, rather your earlier plan of doing some hand watering during the week is perfect.

Your plants, not trying to criticize you or anything. If you wanted a valid method of measurement Bluelab METPULSE Pulse Meter Water 3-in-1 Moisture/Nutrient (TDS)/Temperature Test Kit for Garden Soil, Coco, and Solution, Ester for Hydroponic System and Indoor Plant Grow, Clear Amazon product

That would tell you the story you want right at the root zone otherwise you could distilled or RO water through a pot, collect the runoff and measure that.

I'm very interested to hear this. This strategy of mine is just the verbatim cocoforcannabis procedure, whose goal is to try to keep run-off EC as close to intake as possible. But I'm in total agreement with you based on these last two coco grows... if I just keep the coco moist and supplement my irrigations with semi-regularly handwatering, and if my input is right, I should be fine. Perhaps this run-off business is indeed just unnecessary stress...

Thanks for that link. That's an interesting bit of kit for sure!

-tron

 

[Delps8]

Disclaimer: I'm no lighting expert, so take the following with a grain of salt. There's so much conflicting information out there, my strategy has been pretty much to read as much as I can, then try out a few different things and go from there.

I'm in pretty much the same boat. There's a limited amount of actual and lots of anecdotes. The former is more reliable but it's sparse and only deals with the big issues.

As for the DLI drop in early flower, I suspect this is just a consequence of going from 18/6 to 12/12. If your PPFD stays the same during that transition, you'll have a drop in DLI. And no, I haven't come across any research about Photone's graph, aside from their note that it's based on their own 'personal experience'.

A quick aside, even though the graph shows increasing DLI and hence PPFD gradually throughout flower, I suspect that's largely a consequence of the plant growing taller and closer to the light. Right now, I can probably leave my light at ~230W, currently getting a PPFD of 645 or so. But the plant is growing taller by the day. I bet if I leave my light height/intensity where it is, and as the canopy grows taller, by the end of the stretch period I might be in line with those DLI targets on the chart for mid flower.

Bah, forgot to write the guy at Photone.

{time passes}

He's in Europe, I'm on the Left Coast so I might have an answer in the AM.

The charts are recommended DLI values, meaning that growers should set their lights and light schedules to those levels. Dropping from 45 to 25, assuming photos and 18/6 then 12/12 - DLI 45 at 18/6 is 695 µmols. 695 at 12/12 is 30. The graph shows 25.

Re. growing into the light - that's an factor but it should not be part of guidance. My two GG autos are growing at 1" or 2" a day so I adjust hang height, intensity, and duration. I was using a Royal Blue LED Puck but, now that my plants are getting ready to flower and since I've pretty much had enough "good fun" moving it around in the tent, I'm back to just the main light, a Mars SP 3000. Much less hassle.

As for why I believe autos can tolerate higher DLIs... again, no expert, but here's a hypothesis... the rate of photosynthesis is directly proportional to PPFD, but there is an upper limit to what plants can tolerate. The range is debatable, but without CO2, you'll see a number like 800 PPFD thrown around a lot. Photoperiods and their 12 hour light period are still bound by this ~800 PPFD limit, which at 12 hours is a DLI of ~35.
Since autoflowers can flower with lesser dark periods, this opens up the potential for higher DLIs. The plant cells are still bound by the ~800 PPFD limit (presumably!), but now 800 PPFD at 18/6 becomes 52 DLI.

That's spot on ('cause that's how I figured it, too!)

Long story short, I think my fundamental philosophy when it comes to lighting is to consider the generally accepted "ranges", then take measurements across the full canopy, and adjust lights so that nothing falls outside of those ranges. I've also come to respect the notion that the effects of lighting intensity "plateaus" or "saturates", and it's probably more important to ensure everything is surpassing the lower end of the range, rather than aiming for the higher end of the range, if that makes sense.

Like you, I measure multiple points on the canopy and there are hot spots. One factor is that, even though the canopy is level to within just a few inches, that's enough to cause a significant variance in PPFD. Add in the fact that almost all lights have light falloff at the periphery, thenI just accept that some parts of the canopy are going to have a DLI of N while the rest of the canopy will be at N-x, the latter being the DLI that I want.

I've attached a screenshot of a section of my grow diary. The PPFD values running vertically are for the plants "Wilma" and "Chris". Wilma's light is pretty even with a standard deviation of 62 but Chris is a bit of a problem with an STDEV of 100. The 650 and 650 in bold and italic is a flag that I've fudged the numbers. The actual averages are lower but I'm using 650 as my PPFD so as to err on the side of caution. Wilma was named after Wilma Rudolph. That seedling got off to a rough start and, unlike her namesake who recovered (from polio and then set world records in track), she's not as robust as Chris (Evert) so I'm dialing back a bit.

As for CO2, I've tried one of those plastic soda-bottle style jobbies. It seemed to help out a bit but I never bothered to try again. I think I can eventually grow enough without CO2 to sustain myself, so the next "project" of sorts is UV supplementation in flower. We'll see how that goes.

tron

I bagged my CO2 experiment today. There's lots of RH in the tent now so I've got fans running and have to leave the tent flaps open quite a bit. No chance for CO2 to stay in the tent.

"the next "project" of sorts is UV supplementation in flower. We'll see how that goes."
Sounds interesting. I'll have to check in on that one, too.

 

[Delps8]

Just got a reply from the programmer at Photone and you hit it on the head:
"The sources of research can be found on the bottom of our articles which is this one: https://growlightmeter.com/lighting-requirements-of-cannabis-over-the-full-grow-cycle/#sources
The background generally is light stress: Running the lights at a PPFD of 700 at 18 hours produces a DLI of 45 (the veg target) and then dropping the photoperiod to 12 hours on the same intensity equates to a DLI of around 30 which can then be increased (the PPFD) as the plants get more mature and are better acclimated to high light levels. Staying on the same DLI would require a way higher light intensity that may burn the plants at such an early stage."

The drop in DLI is a function of a ceiling of 700 µmoles and then increasing PPFD to 900 to hit 40 moles. That's right at the non-CO2 supplemented limit.

My response - "Got it — the drop is because of the change in the light schedule. I can see how that works for photoperiod cannabis but what about autoflowers? "

I realize that you're not doing autos, for this grow anyway, but I think it will be interesting to read his reply. BTW, my two GG autos got 46 and 43 moles yesterday, the "sickly" one getting 46 and they responded by growing an inch overnight!