Dahlian was coined by Genderless-Gibberish in response to Justawittyrepartee on July 12, 2018. The term comes from the dahlia flower.
The pink and purple dahlian flag was designed by nova-is-hella-cute (now known as hella-cute-and-fruity) on August 7, 2019. The first four stripes represent the four flags that were created at the time; the red from the azalian flag, the pink from the thistlian flag, the warm purple from the delphinian flag, and the cooler purple from the wisterian flag. The white stripe represents the absence of gender. The green comes from the agender flag.
The red and orange flag was designed by libragender on November 17, 2019 due to thinking hella-cute-and-fruity's flag looked too similar to the plumerian flag. The first three stripes come from the colors of the dahlia flower. The white and green stripes retain their meaning.
On November 29, 2020 libragender posted an updated version of their dahlian flag, They felt that "the red and orange hues were very similar", and adjusted for higher contrast.