OK spacing..i just asked the same question and this is the general idea..some strains grow different and not all lights and bulbs are created equal..so think how much space do you have ? How tall do you want it ? Play with the light ..cfl will be closer then a led or hid, I try to get a inch or more between nodes and im happy..dont worry about space too much at first .Questions are great but DOnt make this too hard and try to be perfect.Just try to keep her green and happy and watch her give you love back