Bought 72 cell hothouse to Propagate plants. How often do I need to water with a spray bottle????
Depends on size of the cells, the type of planting medium, relative humidity, how much water is applied per watering, size of plant as they grow, type of plants (plants' moisture needs), etc.
In other words, there are way to many variables for even a guess. Check the planting medium regularly until you get a good feel for the watering requirements.