Chow_13answered grow question 4y ago Its hard to determine but you should be safe at 60 cm. LED's vary in how bright they are. You would have to let us know what brand/model you are referring to. Is it 300 true watts( pulls 300w from the wall). Is it a cob light or burple ( blue/purple ) light, quantum board. Just a warning, I would not have more then one plant in the same pot at a time. The will compete and bring each other down. A lot of energy will be wasted fighting for root space and light. I would either separate them or select the strongest and kill off the weaker one.