I am planning to make an indoor propagation setup which consists of h:30cm x w:40 x L:50cm recycled polystyrene boxes and full spectrum LED panels. Clearly, the biggest limitation is height in this case. I might join two boxes to double the height, if necessary. The LED panels I have seen keep a temperature of 25C while in operation, but I will clearly drill some holes for ventilation.
The setup is intended to start seeds and grow them vegetatively until they can be hardened off and planted out (this will include vegetable plants).
Edit: I am planning on leaving the polystyrene lid on and attaching the LED panel to it, with the wiring at the top or side; but I am open to other solutions if strictly necessary. The boxes would be placed in a cold part of the house, where the temperature range is 13-18C.
My questions are:
1) What should be the distance for, say, 25W, 45W, 75W panels like these?
2) Would spacing be a problem in the case of a panel? Should I buy strips instead and evenly space them out?
3) How many hours of light per day are suggested in the case of seedlings?