Plants grown indoors require more hours of mild than these grown outdoors. 14 to 18 hours of mild per day is advocated for most fit for human consumption species when grown under artificial lighting. Don't be tempted to go away the lights on 24-7, then again – at least six hours of darkness every day is critical to plant health.
As the flora grow, raise the mild fixture thus to preserve the most appropriate distance, which varies depending on the kind of bulb used and its wattage (the greater the wattage, the farther away the bulb can be). Here are the simple parameters:
Fluorescent Grow Light: 3 to 12 inches
LED Grow Light :12 to 24 inches
HID Grow Light: 24 to 60 inches