Is there a good reason why we cannot use lights for 14-18 hours for DSM? I believe longer light periods are used in agriculture.
If a longer period does work, would additional fert dosing be beneficial - such as spraying with a NPK solution?
I do not think the spray will harm anything, as long as it's dilute.
Sure, you can go longer, but just recall, that the plants will do best with the normal ranges, tropicals will do best at about 12-13 hours, but the last and the starting 1-2 hours do not really count too much unless they are marsh weeds etc.
thanks for responding Tom, but I am not sure I understand what you mean by "do their best"?
are you saying the extra hours wont add to growth or are you saying they wont grow correctly?
Also, how deluted should it be? (how many miligrams of each would you add per 1 liter of liquid?)