stop a week or two before harvest. flush with twice the water of your pot size (growing with 3 gallon pot use six gallons of water to flush) this will clear any nutes leftover and avoid nasty tasting weed. Then use plain water till harvest. Im assuming this is you first grow, you'll be tempted to leave it a little damp or think its dry because it is on the outside...its not. Wait until the stem snaps or just before the stem snaps to remove from the stem and jar or bag up for curing. If you leave it a little too wet your going to end up with grassy smelling meds.