Lorenzo Dow Lewelling was born on December 21, 1846 in Salem, Iowa, United States, the youngest son of William and Cyrena (Wilson) Lewelling and a nephew of Henderson Luelling, who retained the earlier spelling of the name. The family was originally Welsh. Lorenzo's grandfather moved from North Carolina to Indiana in 1825 and with his sons engaged in the nursery business there. When promising reports came to them of opportunities in Iowa several of the sons moved on and established themselves in Salem in the same business. William Lewelling became a minister in the Society of Friends, but he died when his son was only two years old, leaving a family of small children to be brought up by the widow and, after her death, by relatives.