Blanche Evans was the youngest of 12 children born to John and Catherine Evans on a farm in the Brownsville community of Clay County, near Goodwater. She graduated from Lineville High School in 1908 and took a job teaching school at Hatchett Creek Presbyterian Church.
Evans later enrolled at Jacksonville State Normal School and continued her education at Valparaiso University in Indiana. She earned a teaching certificate in 1918 and began working at Shades Valley High School. After four years there she went back to college, earning a degree in chemistry at the University of Alabama in 1924. She returned to Birmingham to teach biology at Woodlawn High School and there developed a hands-on approach to teaching her students about the natural world.
In 1939 Evans resigned and married William Dean. The marriage dissolved within a year, but she kept Dean's name. She resumed teaching at Woodlawn and further developed her field trips as opportunities to observe and record the natural world. Taking the short step toward becoming a conservationist she joined Howard College botanist Herbert McCullough in (unsuccessfully) protesting the destruction of Clear Creek Falls near Jasper by the Lewis Smith Dam.
In the 1950s Dean organized the Alabama Conservation Council and helped found the Alabama Ornithological Society. She was also active in the Alabama Academy of Science, the American Fern Society and the National Association of Biology Teachers and was president of the Birmingham Audubon Society. Beginning in 1951 Dean created and led an annual Alabama State Nature Camp at different sites in Alabama with volunteer teachers.
Dean retired from teaching in 1957 and turned to writing. She compiled a student's guide to the birds of Alabama and later volumes on Southeastern trees and shrubs and on ferns in Alabama. For the latter two books she collected specimens from every county in the state.
In 1967 Dean was instrumental in helping Mary Burks found the Alabama Conservancy, which in turn lobbied successfully for the protection of the Sipsey River Wilderness Area. She was given an award for distinguished service in conservation education by the National Audubon Society that same year.
In 1969 Dean moved back to Clay County and began working on Wildflowers of Alabama and Adjoining States with University of Alabama professor Joab Thomas. It was published in 1973. A year later Dean suffered a stroke and died. She is buried at Hatchett Creek Presbyterian Cemetery in Clay County.
She was posthumously awarded that year's prize for non-fiction from the Alabama Library Association. The Mountain Ecology Workshops held by the Birmingham Audubon Society in Mentone are dedicated to her memory. The Alabama Wildflower Society - Blanche Dean Chapter in Birmingham is named in her honor and sponsors a Blanche E. Dean scholarship. Dean was inducted into the Alabama Women's Hall of Fame in 1985.
- Dean, Blanche E. (1958) Let's Learn the Birds of Alabama, illustrated by Mrs Forrest Watts Bonner. Self-published. Expanded and revised edition published as Birds in 1969 by the Southern University Press
- Dean, Blanche E. (1961) Trees and Shrubs in the Heart of Dixie, illustrated by Mrs Forrest Watts Bonner. Birmingham: Coxe Publishing. Revised edition published as Trees and Shrubs of the Southeast in 1968 by the Southern University Press
- Dean, Blanche E. (1964) Ferns of Alabama and Fern Allies. Northport: American Southern. Revised edition published in 1969 as Ferns in Alabama by the Southern University Press
- Dean, Blanche E. (1972) Happy Trails. Birmingham: Southern University Press
- Dean, Blanche E., Ann Mason & Joab Thomas (1973) Wildflowers of Alabama and Adjoining States. Tuscaloosa: University of Alabama Press. Repurinted in 1983 and 1994.
- Christenson, Alice S., and Larry J. Davenport (Summer 1997) "Blanche Dean, Naturalist." Alabama Heritage pp. 16–23
- Christenson, Alice S. (February 4, 2008) "Blanche Evans Dean". Encyclopedia of Alabama. Beta version. - Accessed May 7, 2008
- Blanche Evans Dean at the Alabama Women's Hall of Fame