From the middle of the nineteenth century to the beginning of the First World War was the hey-day of the professional gardener. However, time has eroded the memory of these men and many of the gardens where they worked have disappeared or have been radically altered. Most garden history has been written from an artistic or design perspective. No-one has studied the lesser head gardeners who worked in British gardens and estates, nor has there been a county study such as this which considers the working lives of gardeners from a commercial and practical point of view. Yet research using contemporary documents, such as the census and estate records, suggests the number of working gardeners increased significantly throughout the nineteenth century. Private gardeners worked in growing numbers of middle-class villa gardens, or for estate gardens which had returned to formal planting and mass bedding. Nurserymen contributed plant material to support garden owners' aspirations and ambitions to purchase the newest imports or fashionable hybrids and to furnish glasshouses and arboreta. Market gardeners supplied fruit, vegetables and flowers to satisfy the demands of a society which had changed from being largely rural to predominantly urban and began to specialise and produce for long distance markets. Working gardeners were compelled to change their practices and products in order to accommodate scientific advances which fuelled a rise in interest in gardening across all classes of society. As the century progressed it became harder for a garden labourer to attain the position of head gardener. Increasingly, it was a man with some education who underwent a gruelling apprenticeship and training to reach the top of his profession. Different branches of the trade had their own hierarchy led by nurserymen at the top, jobbing gardeners and labourers at the bottom. This thesis discusses the growth of professionalism of gardeners and concludes that practical training was insufficient for success; self-education, determination, experience of a wide variety of gardens, good management skills, and sometimes luck were needed in order to succeed.