Verkkoyou can do this by periodically dipping the drill bit in cold water or using a coolant while drilling. Drill at a slow speed. Place one hole in the center, and if more than one is necessary, take care to evenly space them around. Verkkoplacing holes on the sides of a plant pot improves both water drainage and aeration in plants. The number of holes should be between 4 to 8, at 1″ diameter per hole,.