Lighting PAR meter - LED Light cycle for Auto Plants

[Stone420]

Greetings:

I'm learning to evaluate lighting requirements for my cannibas indoor grows by using a par meter to determine my DLI for plants. There is some reading I've done to achieve the proper daily Moles of light needed for optimum plant growth.

My question primarily goes back to what light cycles are best for auto flowering cannibas strains. The electricity rates are sky high in my area, plus we are going to need air-conditioning to keep the grow area optimum. One way I'll achieve this is by running the QB lights at night although they don't generate as much heat as other forms of lighting.

To veg the plant, I always like 18 hours of light with 6 hours of dark so the roots can develop....in other words, give the plant a break. Once we go into flower, would it make sense for me to drop my lights to 16 on and 8 off? The more dark time I have, the lower my power bill. BUT, I don't want to be penny wise and pound foolish and screw up a yield by shaving light time off my grow.

Suggestions?

 

[Death The Cultivator]

Greetings:

I'm learning to evaluate lighting requirements for my cannibas indoor grows by using a par meter to determine my DLI for plants. There is some reading I've done to achieve the proper daily Moles of light needed for optimum plant growth.

My question primarily goes back to what light cycles are best for auto flowering cannibas strains. The electricity rates are sky high in my area, plus we are going to need air-conditioning to keep the grow area optimum. One way I'll achieve this is by running the QB lights at night although they don't generate as much heat as other forms of lighting.

To veg the plant, I always like 18 hours of light with 6 hours of dark so the roots can develop....in other words, give the plant a break. Once we go into flower, would it make sense for me to drop my lights to 16 on and 8 off? The more dark time I have, the lower my power bill. BUT, I don't want to be penny wise and pound foolish and screw up a yield by shaving light time off my grow.

Suggestions?

There's a thread on the topic but no general consensus on what's best. 18/6 20/4 24/0. I don't see why any of those wouldn't work especially if you aren't driving your boards hard

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[Stone420]

I think my lighting DLI will boil down to how hard to push the power driver to achieve the daily Moles I want. If I scale down to 16 hours light on, I can achieve my DLI fine by turning up the umoles, but I don't want to risk burning or bleaching plants to do this. Good thing is the LED QB's are much more forgiving in the heat category.

I actually looked for a thread such as you mentioned @Damien50, and if you have ready access to the link, I'd surely appreciate that. Thanks!!

 

[Simplicio]

Greetings:

I'm learning to evaluate lighting requirements for my cannibas indoor grows by using a par meter to determine my DLI for plants. There is some reading I've done to achieve the proper daily Moles of light needed for optimum plant growth.

My question primarily goes back to what light cycles are best for auto flowering cannibas strains. The electricity rates are sky high in my area, plus we are going to need air-conditioning to keep the grow area optimum. One way I'll achieve this is by running the QB lights at night although they don't generate as much heat as other forms of lighting.

To veg the plant, I always like 18 hours of light with 6 hours of dark so the roots can develop....in other words, give the plant a break. Once we go into flower, would it make sense for me to drop my lights to 16 on and 8 off? The more dark time I have, the lower my power bill. BUT, I don't want to be penny wise and pound foolish and screw up a yield by shaving light time off my grow.

Suggestions?

From https://www.autoflower.org/threads/whats-the-best-lighting-cycle-for-autos-24-0-20-4-or-18-6.3691/
What is the best lighting cycle for autos?

1. 24/0 (lights on/off)............ 203 vote(s)...18.8%
2. 20/4 (lights on/off)..............477 vote(s)...44.2%
3. 18//6 (lights on/offf............. 86 vote(s)....35.8%
4. Other......................................57 vote(s)......5.3%
   

 

[Death The Cultivator]

I think my lighting DLI will boil down to how hard to push the power driver to achieve the daily Moles I want. If I scale down to 16 hours light on, I can achieve my DLI fine by turning up the umoles, but I don't want to risk burning or bleaching plants to do this. Good thing is the LED QB's are much more forgiving in the heat category.

I actually looked for a thread such as you mentioned @Damien50, and if you have ready access to the link, I'd surely appreciate that. Thanks!!

Well genetics will be a factor as well. I think any consistent light schedule will work with a stable dialed in environment. I ran 24/0 on 00 Seeds Northern Lights Auto because I lacked the tools to manage my environment properly with lights on/off schedules and did fine. This time I'm running photos but I have temperature and humidity controllers so I'm not concerned with lights off temps and humidity.

Many ways you can go about it. How you train, feed, environment, genetics will play a role as well and even 12/12 would be fine depending on your goals

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[Stone420]

Thanks @Damien50 and @Simplicio ! Being in the southeastern US, the warm weather will be a factor to run A/C to keep the temps moderate in a not so well insulated farm cabin. The more I can do to control exorbitant electric costs, the better I'll make out in the long run.

Trying to evaluate the savings, I kicked around the idea of running 20/4 for the first 4 weeks to veg the plant into a bigger plant, then slowly scale back to 16/8 for the duration of the grow. This will be a northern lights auto strain from ILGM, so I really don't know where they source their seeds.

HOWEVER, if cutting back to 16/8 ends up extending the grow, I may be costing myself more in the long run by trying to pinch electric costs.

Still trying to sort this out and not make mistakes in the process.

 

[Stone420]

@Damien50 - may I ask about your controllers?

I have a humidifier in the tent controlled by an Inkbird RH% controller. I have a dehumidifier in the room (not in the tent) to run when the RH% is higher in certain seasons and the Inkbird controls that device too. My LED QB lights typically increase the tent temps by 7F over ambient of the room. I leave my intake fan on all the time and my filter/exhaust fan is variable speed and I vary that depending on the plant stage. I can always get a good tent wall draw in (Vacuum) regardless of the exhaust fan speed.

Based on the info just provided, do you think a controller system would be an advantage for me?

 

[Death The Cultivator]

I have the Inkbird humidity and temperature controllers hooked to a heater, humidifier, an intake, and an exhaust fan. I keep my tent sealed for the first two weeks at 77-82f and 72-77% RH all through veg. The exhaust fan pulls humidity while the intake lowers temps especially when my AC is on. Once flowering starts I drop the humidity to 60% and keep my temps consistent.

The controllers helped me stabilize my environment where before I was hanging wet towels and my cheap heater was running infinitely. If you aren't concerned about yield you could always do 12/12 from seed to finish which many people do with photos.

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[Stone420]

I have the Inkbird humidity and temperature controllers hooked to a heater, humidifier, an intake, and an exhaust fan. I keep my tent sealed for the first two weeks at 77-82f and 72-77% RH all through veg. The exhaust fan pulls humidity while the intake lowers temps especially when my AC is on. Once flowering starts I drop the humidity to 60% and keep my temps consistent.

The controllers helped me stabilize my environment where before I was hanging wet towels and my cheap heater was running infinitely. If you aren't concerned about yield you could always do 12/12 from seed to finish which many people do with photos.

CobsCocoDTWMxPScrog Watch Me Mess Up

Thank you for the detailed information. I may try bumping up my humidity a few points to match your levels.

12/12 may definitely be a cost saver on the electricity bill. Not sure how well the plant will veg and their size with short light cycles. But, like you say, I don't see any reason that wont work.

 

[Death The Cultivator]

Thank you for the detailed information. I may try bumping up my humidity a few points to match your levels.

12/12 may definitely be a cost saver on the electricity bill. Not sure how well the plant will veg and their size with short light cycles. But, like you say, I don't see any reason that wont work.

@coalminer grew some Extrema on a 12/12 and they turned out fine. I think 12/12 would be fine.

Are you aware of VPD vapor pressure deficit?

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