Optimizing Cannabis Growth: Gavita 1700e Lights, CO2, and Canopy Distance

[muzzle]

I've been diving deep into optimizing my cannabis grow setup, specifically with Gavita 1700e lights, CO2 supplementation, and canopy management. I'm aiming for the best results within an 8-week grow cycle, and I'm looking to discuss the ideal strategies.

1. Gavita 1700e Lights:

The Gavita 1700e is known for its intense light output. I've heard varying opinions on the optimal height and intensity settings during different growth phases. What has worked best for you in terms of:

• Flowering Stage: What adjustments do you make to maximize bud development and resin production?

2. CO2 Supplementation:

CO2 can significantly enhance plant growth when used correctly. What methods of CO2 supplementation have you found effective? I'm particularly interested in:

• CO2 Levels: What ppm levels do you maintain during different growth phases?

3. Canopy Distance:

Maintaining the right distance between the canopy and the light source seems crucial for light penetration and heat management. What strategies have you employed to create the optimal canopy environment throughout the grow cycle?

• Height Adjustment: Do you adjust the height of your lights as the plants grow? If so, how frequently and by how much?

4. Achieving the Optimal Bell Curve:

Ideally, I'm aiming for a growth pattern that follows a bell curve, with vigorous vegetative growth transitioning smoothly into robust flowering and ultimately a strong finish. What specific practices or techniques have helped you achieve this ideal growth curve?

I'm eager to hear your experiences and any tips you have for fine-tuning these variables to achieve the best possible yields and quality within an 8-week timeframe.

Currently, this is how I'm running it, but I am getting seed pods and it seems like my plants are getting stressed out and I can't find the root cause.

I'm running the canopy 12 - 18 inches in most cases. No light bleaching.

Here are some images going into chop during flush.

 

[013]

most of this is over my head cuz I don’t run CO2 or track light output etc.

and feel certain you know all this before I utter a word anywho normally room temp should be 80 to 84 without CO2 and with it you can defs run warmer room temp well above the 84F, you mentioned seed pods but the fan leave serrations are looking pretty stressed

but the main point here is to bump you to top of list and call in the bug guns with @Delps8 and @bluter

that’s a monster light and seriously chunky colas

 

[Delps8]

I've been diving deep into optimizing my cannabis grow setup, specifically with Gavita 1700e lights, CO2 supplementation, and canopy management. I'm aiming for the best results within an 8-week grow cycle, and I'm looking to discuss the ideal strategies.

1. Gavita 1700e Lights:

The Gavita 1700e is known for its intense light output. I've heard varying opinions on the optimal height and intensity settings during different growth phases. What has worked best for you in terms of:

• Flowering Stage: What adjustments do you make to maximize bud development and resin production?

2. CO2 Supplementation:

CO2 can significantly enhance plant growth when used correctly. What methods of CO2 supplementation have you found effective? I'm particularly interested in:

• CO2 Levels: What ppm levels do you maintain during different growth phases?

"resin production" - there's a lot of buzz around using UV to enhance secondary metabolites. I haven't seen any indication that UV actually does that. The commonly cited study is about 30 years old and the researcher stated that the results wee "equivocal" because one grow saw an increase in secondary metabolites while the other didn't.
To a marketing person, the fact that one grow improved is absolute proof that UV is a valuable addition and many light vendors now sell UV supplemental lighting.
I'm a strong follower of Dr. Buce Bugbee, a researcher in the cannabis field, and, as a scientist, he as access to a dictionary so he sees equivocal as meaning equivocal.
One of Bugbee's student is Mitch Westmoreland who released a couple of videos on YouTube earlier this year. The topics he discussed were part of his PhD thesis and UV was one of the topics. Despite their efforts, they haven't been able to show an improvement in secondary metabolites but he states, as he should, that that doesn't mean that you can't improve secondary metabolites rather it means that, despite their efforts, they couldn't find a way to increase secondary metabolites but, he continued, that it's possible that some combination of the different wavelengths + intensity + timing + duration could have an impact on secondary metabolites.
The bottom line - there's no indication that UV consistently improves secondary metabolite production but it can't be ruled out.

"Maximize bud development" - crop yield and crop quality increase in an almost linear manner as light levels increase, up to the light saturation point. Crop quality is defined as the ration of the mass of flower to the mass of the above ground foliage.

There's quite a bit of research to substantiate my statement, the best summary of it is in the videos that Westmoreland released earlier this year. The two videos are similar in content and run about 50 minutes each. I strongly recommend them. I've spent hundreds of hours learning about cannabis grow lights and lighting so I was familiar with most of his findings but he did have some very new research that have caused me to rethink how I grow cannabis.

RE. "bud development and resin production" - per Westmoreland, get as much light was you can on your plants while allowing ambient temps to rise in the mid-80's. The higher ambient temps encourage maximal growth. Once the plant stops building out its structure, which will be in about the second week of flower, continue to give your plants as much light as possible but ensure that the temperature at the tops of the flowers is <=78°.

The high temps + high light in veg will tend to maximize growth and production of secondary metabolites and keeping termperatures <78° will tend to preserve those secondary metabolites.

Westmoreland published a vide on "Hemp" about three years ago and said that temps over 78° "wiped out" (my phrasing) secondary metabolites but there as no follow up. It wasn't until he published his research that additional detail was available. As a result of his research, I've retired my Growcarft flower light (from 2020 and have bought a very high output light from Spider.

Your light generates about 700µmol at 24" and has signficant rolloff as you move away from center. That's not unusual with a light of that vintage (my Growcraft was a 2020 model, as well which means that it was designed 2018±).


As hang height increase, PPFD drops off but uniformity increases.

If you're running CO2, the only advice I found on that (I grow in a tent so CO2 supplementation is not part of my growing processes) is from Bugbee who advises 1200ppm and 1200µmol.

In order to achieve 1200µmol with that light, you're going to have to drop the light to 12'±? Since the light is being lowered, uniformity will tend to drop so, while you may have 1200 in the center, you're going light falloff.

How much? Don't know but I would strongly suggest that you buy a lux meter ($32 will get you a Uni-T from Amazon) or $600± for an Apogee. I've tested the Uni-T against my Apogee and the inaccuracy is linear up to 1000µmol, the highest PPFD I used. I have no reason to not believe that it will be inaccurate at 1200µmol.

I would not try to run a 5' x 5' tent using CO2 without a light meter. It's a trivial expense and a non-trivial amount of plants.

If you're already in flower, get the light meter, fire up the CO2, and figure out your hang height and dimmer settings. A a hang height of 12" is a good start or even 14". The trick is to up the light levels to, say 800µmol and observe the plants. With CO2 you should be able to get at least 1100µmol on your grow. If not, it's time to troubleshoot. I run my 2' x 4' at 1100µmol in ambient CO2 (450ppm) so 1200 should not be an issue.

3. Canopy Distance:

Maintaining the right distance between the canopy and the light source seems crucial for light penetration and heat management. What strategies have you employed to create the optimal canopy environment throughout the grow cycle?

• Height Adjustment: Do you adjust the height of your lights as the plants grow? If so, how frequently and by how much?

Per above, intensity decrease as hang height increases. Uniformity increase as hang height increases. If you've want to get 1200µmol on your grow with that light, you're going to have to drop it a bit.

As hang height decreases, the temperature at the tops of the flowers will increase so a tradeoff between hang height and the temperature of your flower tops. To me, the latter is key. I've grown cannabis with temps in the low 80's in flower and there was a stunning amount of flower but it didn't have the potency that I was expecting. When listened to the Westmoreland videos, the light went on, figuratively and literally.

4. Achieving the Optimal Bell Curve:

Ideally, I'm aiming for a growth pattern that follows a bell curve, with vigorous vegetative growth transitioning smoothly into robust flowering and ultimately a strong finish. What specific practices or techniques have helped you achieve this ideal growth curve?

I'm eager to hear your experiences and any tips you have for fine-tuning these variables to achieve the best possible yields and quality within an 8-week timeframe.

Currently, this is how I'm running it, but I am getting seed pods and it seems like my plants are getting stressed out and I can't find the root cause.

I'm running the canopy 12 - 18 inches in most cases. No light bleaching.

Here are some images going into chop during flush.

If plants are stressed, it could be too much light or temps that are too high. If you've got seeds pods, I think that means that they've revegged. I'll take a look at the photos and see if anything comes to mind.