Lamp operating hours and effect on plants

The lamp is quite bright. Using it as a nitelight so no need to turn on other lighting (save energy).

Currently Lavender, strawberry, tomato, french marigold, basil, sweet alyssum. Started 1 week ago.

French marigold, basil, sweet alyssum sprouted.

Temperature range is approx 27 ~ 31°C.

So how many hours of darkness do you recommend?

Previously I have grown strawberry, tomato, basil.

tomato flowered and bear fruit… but only like, 1~2 fruits actually matures. then it dies. the 2 tomatoes like tasteless.

strawberry grew and flowered, but never bear a single fruit, then it dies.

Didn’t thin the plants then (no such guides or advise available 1 year ago). So it may not be attributed t the extended light exposure.

basil grew quite vigorously. Managed to re-pot it. That’s the only thing that is considered a success with my experience with C&G.

I restarted the SGs after about 1 year, and I want to get it right, hence asking for advises from experts.

Just before this latest endeavor, I planted 3 batches of basil, marigold, alyssum, lavender. None germinated. But this is off-topic.