Garvie was born in Edinburgh, Scotland and moved to South Africa in 1883 with his parents and two brothers. In the mid 1890s he travelled around Southern and Central Africa. During the Boer War he took part in the Siege of Kimberley. Thereafter he married Nellie Steyn, an Afrikaner and relation of Martinus Theunis Steyn, then President of the Orange Free State.