What finally led to Jamestown's economic success?

The settlement at Jamestown faced many hardships.  The original settlers had expected to find silver and gold in abundance in the New World.  Instead, they were faced with poor soil, mosquitos, and a lack of food.  They suffered a harsh winter where many people starved.  After this, all of the settlers were prepared to leave.  A supply ship arrived and some settlers decided to stay.
Those who stayed still faced many hardships.  They were not farmers, and they had to learn how to grow crops.  In the end, agriculture became the saving grace for Jamestown.
John Rolfe arrived in Jamestown.  He was an expert in growing tobacco.  He had studied a new kind of tobacco from Trinidad.  He brought seeds with him to Jamestown.  John Rolfe grew the tobacco and taught others how to cultivate it.  Soon tobacco became the primary export crop for Virginia.  Eventually, it made farmers in and around Jamestown wealthy.  It also made the small economy there strong.