There are varying opinions on that. If you are living in an English-speaking environment, and immersed in the language, you may pick up a workable knowledge of the language without explicitly learning grammar. But even then, it would take you much longer.
You're far more likely to recognise patterns if you sit down and study them for a while every day. But then, I love grammar, within reason, so I would say that. (Even so, Second Language Acquisition experts generally agree.)
Student or Learner