There is a confidence in Rachel Doyle’s voice that comes from doing things her own way.  Growing up in a “disadvantaged” but “privileged” home, she studied horticulture at college before quickly enacting her dream of owning her own garden centre, her passion for gardening having come from her father who grew everything that his family ate. Initially, she ran her business out of her backyard, with hand-painted signs on old pieces of timber. Almost fifty years later she has turned her dream into one of the most acclaimed garden businesses in Ireland. Now called The Arboretum, it employs 170 people…