In the same year, John Rolfe began experimenting at Varina, his plantation, with some tobacco seeds brought from the West Indies or from South America. Pocahontas helped Rolfe in this task by teaching him the necessity of keeping the young, tender leaves protected from the cold and by showing him how gently the young tobacco plants must be transplanted. Rolfe became the first white man to raise tobacco successfully in Virginia. Then the problem of curing tobacco in such a manner that it could reach England without spoilage faced him. After some experimentation, his shipment was the first one to reach England in good condition. As a result, tobacco became the first important money crop and export of Virginia. In addition to the price the planters received for this product, the production of tobacco created employment for merchants and shippers. After Rolfe's success in growing and curing tobacco, it was grown by practically everyone in a variety of places: fields, gardens, between graves and, in some instances, in the streets of Jamestown. Prosperous times had finally arrived at Jamestown. When the Englishmen at home realized the profit and excellent opportunities available in tobacco growing, many journeyed to Virginia and began tobacco raising. Previously, the settlers' occupations had consisted primarily of farming (especially the cultivation of grapes) and of the manufacture of potash, soap, glass and tar. The successful growing of tobacco caused a tremendous increase in the population of the colony and in the amount of tobacco shipped from Virginia. This infant tobacco production was the background for the present day high rank of Virginia in tobacco production. In 1616, the company allowed each settler to have 100 acres of land for his personal use. A few years later, a 50-acre tract of land was awarded to each settler who paid his own fare to America and an additional 50 acres for every pioneer he brought with him. This land arrangement, called the "Head-Right" system, formed the basis of the Virginia land system. This system resulted in the creation of large estates, and in the 1650's the average size land grant in Virginia was approximately 500 acres. Such areas were commonly called plantations, and the owners of such plantations, known as Virginia planters, ultimately became the dominant influence in the Virginia government. Some of these early plantation owners were William Byrd, Thomas Warren, William Fitzhugh and Abraham Wood.