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Eastern Pennsylvania

Supposing this factor is under your control, what do you think the optimal day/ night ratio is? I recall that plants perform different respiratory/ metabolic functions at daytime vs. nighttime. This also varies between plant varieties. For tomatoes, do you think your earlier plants get the best tomato growth, or the later plants? What I am wondering is if I'm giving my plant enough "nighttime" hours in the grow room. Right now it is 16/8. I do not have a tomato set yet. There is a possibility that during vegetative stage one ratio is preferred and after fruit set another ratio would be better. Just looking for opinions and observations. thanks

1/25/2021 10:17:32 AM

Central NY

I have no idea...but wonder if the plants being indeterminate should figure in as you adjust for your target. They look great so far...good luck

1/25/2021 10:39:50 AM

On top of Brush Mountain, Pa.

In the daytime the plants are using photosynthesis to produce carbohydrates. At night they use the carbohydrates for actual growth, making roots, stems, leaves etc. I see nothing wrong with what you are now doing.

1/25/2021 6:12:55 PM

Grittyville, WA

Washington State and New York Im guessing are at about 8.5- 9 hours of night on the solstice. Maybe thats optimal since thats where the 9+ lb tomatoes are from. I dont think its quite like cabbages that benefit from 20 hrs of light in Alaska. If they needed 20 hrs of light the numbers would shift northwards?

1/25/2021 7:03:52 PM

Norfolk, UK

Believe they need 6 to 8 hours nighttime.

In terms of light, it will be quality / intensity of light in addition to ‘length’. Vegetative state will need less than generative phase.

There is lots on the steering growth vegetative or generative via temperature profiles and differentials (need a moment to reply to other thread on this - will do soon!), but I’ve heard little on different day / night lengths.

1/26/2021 5:34:01 PM

Wallingford,CT

I grew tomatoes inside one year. Had beautiful plants, perfect lighting, soil and moisture. Never got any to set. Seems the issue is temperature. Need to have a significant temp drop at night for them to set.

1/27/2021 7:20:28 AM

Team Canuckle Heads

I had the same problem as Bart with my first set but thought it was more the lights. first set were left under the T8's and none would set.
The second set were started under the T8's then moved under a grow light with just the red spectrum turned on once they flowered and everyone set.
My table stays pretty close to 75° all the time

1/27/2021 10:26:09 AM

Eastern Pennsylvania

Thanks for the input all. The temperature changes about 12 degrees between light on and light off. Does that seem like enough separation?

1/27/2021 4:04:52 PM