As an American, let me just say I am embarrased that many people in this country, don't know how long a meter is. For some reason we still think that "standard" makes more sense, while for the entire rest of the world metric is standard. About your original question, it depends of course on what growing meathod you are going to be using. you have to decide if you want a few large plants, or a lot of little ones.
good luck