William is a qualified horticulturist and is a member of the Australian Institute of Horticulture and the Royal Horticultural Society.

Dangar began his horticultural career when he moved to Sydney from the country in 1991 to work for a city based landscape company.  Upon being made redundant he started his own contracting company whilst studying at Ryde School of Horticulture.  

William formed an association in 1992 with Marcia Hosking a fellow landscape designer. This collaborative relationship allowed him to fully develop an appreciation of good design. In 1995 the landscape contracting division of this business closed allowing Dangar to focus solely on design and implementation of his own creations.  Since this period he has worked on over 600 projects nationally.