There are a lot of factors that go into this calculation. What style of growing? How big do you want your plants? A general rule of thumb is to use 1/4 - 1/3 of the space for veg and the rest for flower. You can manage your flower room to also serve as a drying room utilizing the ceiling space for a line. If you feel you need a proper drying tent well that needs it's own thinking depending on the size of the tent you want. However, it is a frill and you can do without it. Once ready for curing you'll pop the buds into mason jars and store so there is little space requirement there. Hope this helps!