I recommend 18 hours of light, and 6 hours of darkness.
Complete darkness is not essential during this vegetative time.
When a seedling is 6-8 weeks old or more, generally, you can reduce the hours to induce flowering.
(A Cutting may already already be this old as it comes from a larger plant)
The plant counts the DARK HOURS not the light hours.
So if you remember this, any short period of darkness will make a plant grow in a vegetative way.
They need at least 15 minutes of night to realise it is night. Less than 15 minutes should not register.
Just a standard Fluro can keep them “awake” if you desired to, say turn off the lights for cleaning etc. i.e. not a lot of light for day/night length control, but lots of light for getting growth/flowering to happen. So you can control the length of day without using “grow lighting”
To flower a plant, they must get at least 12 hours of total complete darkness.
You can run the light on for days if you want, but the dark period must not be less than 12 hours.
So if you run 12 hours on, and 12 hours off that is the normal program.
If you can see anything when the light is off (due to glow of red power indicators, light under the door, glow through the curtains) the plants may take a week to several weeks longer to finish.
Don’t panic if you can’t do this.
If the power goes off for more than 15 minutes, the plant will detect a short day and may be confused for up to a week before resuming flowering – so if the power is off, try to unplug the light, and resume lighting 12 hours later. Run the light for more than 12 hours until you catch up with the plants normal off time.
My growing guides are at http://hydrocentre.com.au/growing-info/ and is free. There is a hydroponic guide and the indoor growing guide is lower down on the page.
Nerang Hydroponic Centre 4/50 Spencer Road Nerang QLD 4211 Australia Phone (07) 5527 4155
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