At around the age of seven, he attended a school in a neighboring parish, where he became known for his tardiness and truancy, preferring to explore the countryside during his two-mile walk to class.

[3] He attended school in Kinnoull, on the eastern banks of the River Tay, and upon leaving found work as an apprentice to William Beattie, head gardener at nearby Scone Palace, the seat of the Earl of Mansfield.

William Jackson Hooker, who was Garden Director and Professor of Botany, was greatly impressed with him and took him on an expedition to the Highlands before recommending him to the Royal Horticultural Society.

The Royal Horticultural Society[7] sent him back on a plant-hunting expedition in the Pacific Northwest that ranks among the great botanical explorations.

He was last seen alive at the hut of Englishman Edward "Ned" Gurney, a bullock hunter and escaped convict.

A monument was built, at the spot where Douglas died, by members of the Hilo Burns Society, including David McHattie Forbes.

It is called Ka lua kauka ("Doctor's Pit" in the Hawaiian language), off Mānā Road on the Island of Hawaiʻi (19°53′17″N 155°20′17″W / 19.88806°N 155.33806°W / 19.88806; -155.33806 (Kaluakauka)).

[13] A species of "horned toad", Phrynosoma douglasii, is named in honor of David Douglas.

In Vancouver, Washington, he is remembered via David Douglas Park which was used during World War II as interim housing for the Kaiser Shipyard workers living in little silver trailers, giving the area the brief nickname during the era of "Trailer Terrace Park.

The actor Alvy Moore was cast as Douglas in the 1962 episode "The Grass Man" of the television series Death Valley Days.