Stonerdanswered grow question 4 years ago It usually depends on your grow space and the lighting that you plan to use!
Ideally in a 3sqf/1sqm you want 9 plants potted in 11 liter pots when considering grow space.
When talking about lighting it depends on what type of lighting you use (LED, HID, HPS), the power consumption (watts -W), and the PPFD (actual PAR/light that reaches the plant at a specific distance).
LEDs have a very versatile use and are usually measured by their PPFD which are recommended in the 600-1000 range and it is usually stated with distancing in the LED info online or in user manual.
HID/HPS are usually measured by power consumption or Watts/W, I believe that 400W will be enough for a 3-4sqf area and a 600W will be enough 4-5sqf area but it also depends on distance from plants.
Hope this helps! Good luck and happy growing :)