Born in Brevik, Norway, Heistad studied landscape gardening and horticulture in both Norway and Denmark. After completing his education he worked as a foreman in a number of landscaping and horticulture firms in Germany. In 1905, Heistad arrived in the U.S. and found work as a carpenter and as an estate gardener. He was introduced to Maine in 1910 while employed by the Olmsted Brothers at Chatword, the Joseph Pulitzer Estate in Bar Harbor. He moved permanently to Maine that year and provided design services for numerous private estates in the Camden/Rockport area. Most of Heistad’s residential work is no longer extant, but his design for the John Gribbel estate, Weatherend, has survived. The plan for the grounds exemplifies his integration of existing materials, including native plants and local stone, with other designed elements on the site.
Throughout the 1920s Heistad continued to receive commissions on private estates. During the Great Depression he worked more in the public sector. From 1934 until 1942, he served as staff landscape architect at Camden Hills State Park, a Civilian Conservation Corps project. Consistent with his earlier residential work, the architecture of the park is integrated into the existing landscape. His tenure at the park ended in 1942 when the CCC was disbanded.