- 1909: Born Margaret Ursula Brown on 22 May in Chesham, England.
- 1926: Enrolls in Watford School of Art.
- 1932–1933: Travels to Germany, witnesses rise of Nazi government and Reichstag fire.
- 1936: Marries trade activist Reginald Bruce Bartlett in January.
- 1943–1947: Divorces Bartlett. Enrolls as a night student at St. Martin’s School of Art, Westminster, meets fellow student and lifelong partner Greville Mee.
- 1947–1949: Studies at Camberwell School of Arts and Crafts in south London under Victor Pasmore on a postwar grant.
- 1952: Greville and Margaret (surname changed to Mee by this time) travel to São Paulo to help her ailing sister Catherine. Margaret begins teaching art classes and Greville works as commercial artist. They explore the local forests and Margaret begins painting the local flora.
- 1956: Catherine returns to England and passes away. The Mees decide to remain in Brazil, and Margaret organizes her first expedition, to the Rio Gurupí in northern Brazil. She travels to Belém to meet Walter Egler, agronomist and director of the Museu Paraense Emílio Goeldi. From there, she travels down the Amazon and draws several plants, including Eucharis amazonica (in the Dumbarton Oaks collection).
- 1958: Mee’s first Amazon paintings are exhibited at the São Paolo Botanic Institute, followed by a larger exhibition in Rio de Janeiro, through which she meets landscape architect Roberto Burle Marx and establishes a lasting friendship. She begins systematic research on tropical plants at the São Paolo Botanic Institute and meets many important botanists, including Lyman Smith of the Smithsonian Institution.
- 1962: Second expedition, in Mato Grosso, funded by the São Paolo Botanic Institute and Lyman Smith focusing on bromeliads, a major subject of Smith’s research. Mee contracts malaria during her work and falls critically ill, but is able to return with samples, including two new species that are later sent to the Botanic Institute.
- 1964–1965: Third expedition, to the Rio Uaupés (a tributary of the Rio Negro) near the Colombian border, the first of three expeditions to the far north. Mee paints Streptocalyx longifolius (in the Dumbarton Oaks collection) and a new variety of Heliconia that is later named after her (Heliconia chartacea var. meeana). Mee discovers a new species of bromeliad along the Rio Içana (another tributary of the upper Rio Negro) in January 1965. Smith names the species Neoregelia margaretae after her three years later.
- 1966: Mildred Bliss acquires the first three paintings by Mee (Rapateaceae, Streptocalyx longifolius, and Heliconia) and invites Mee to offer a lecture and exhibition of her work the following spring.
- 1967: Mee visits Washington, DC, in April, gives a lecture at Dumbarton Oaks and visits the Smithsonian. Mildred Bliss subsequently acquires 18 more paintings by Mee for a total of 21. The National Geographic Society sponsors her fourth expedition, to Serra da Neblina, the “Mountain of Mist” in northeastern Brazil, and sends photographer Otis Imboden to document this journey. Mee is the first woman to attempt to climb the peak of the mountain from the south but is forced to turn back by crumbling paths. Mee extends her work in the north by two months to make her fifth expedition to Rio Marauiá, where she meets the Yanomami, an indigenous group whose members help her navigate the area.
- 1968: Mee returns to England in January only eight days before the launch of her exhibition at the Tyron Gallery, London, and the publication of her book Flowers of the Brazilian Forests. She falls ill with hepatitis upon arrival and takes two years to recover.
- 1970: The Mees move to Rio de Janeiro and Margaret undertakes her sixth journey, to the Rio Demini, painting Gustavia pulchra (Royal Botanic Gardens, Kew), signaling a shift toward painting flora in its native environment that characterizes her later work, in response to the threat to the Amazon rainforest caused by government road building and mining.
- 1971: Seventh expedition, to the Rio Maues, the first of two expeditions funded by a Guggenheim Fellowship, and the first of four trips along the Rio Negro south of Manaus.
- 1972: Eighth expedition to the Rio Mamori and the Rio Marau. At the latter, she discovers and collects another two new bromeliads, Aechmea polyantha and Aechmea meeana, the latter named after her. Mee writes a report for the Forestry Development Institute, drawing attention to the devastation around Manaus and the damage caused by unregulated trade in forest products.
- 1974: Ninth expedition, to Manaus.
- 1975: Tenth expedition, to Manaus; Mee is granted honorary citizenship of Rio de Janeiro.
- 1976: Receives the British MBE.
- 1977: Eleventh expedition, looking for the extinct Rio Cauhy and the blue qualea. Although the search for this flower was unsuccessful, another specimen Mee collected in November of the previous year, Sobralia margaritae, is named after her.
- 1979: Awarded the Brazilian order of Cruzeiro do Sul.
- 1980: Published Flowers of the Amazon with support from the Brazilian government. Launches an exhibition at the Natural History Museum in London. Marries Greville on 8 October.
- 1982: Twelfth expedition, to the newly created Anavilhanas National Park, a large archipelago near Manaus along the Rio Negro.
- 1984: Thirteenth and fourteenth expeditions, to the Rio Trombetas in Pará to see the biological reserve created in 1979.
- 1986: Granted fellowship of the Linnaean Society. During an exhibition of her Amazon Collection of 60 paintings at the Missouri Botanical Garden, Mee campaigned against environmental damage, pollution, and species extinction.
- 1988: Fifteenth and final journey along the Rio Negro, near Manaus, to paint the blooming of the Amazon moonflower Selenicereus (Strophocactus) wittii, documented by photographer Tony Morrison, during which Mee celebrates her 79th birthday. This journey serves as the basis of the 2012 Brazilian documentary Margaret Mee and the Moonflower. Later in the year, Mee begins discussions that lead to the founding of the Margaret Mee Amazon Trust (MMAT) to help the Botanic Garden at Kew acquire the 60 paintings comprising the Amazon Collection and to create a scholarship program to support forest conservation. Tragically, she passes away on 30 May after a car accident in Leicestershire, England. Following her death, Philip Jenkins sets up a sister organization of the MMAT based in Rio de Janeiro: the Fundação Botânica Margaret Mee (FBMM), promoting local scholarships in Brazil.
- 1990: MMAT purchases 29 paintings from the Amazon Collection for Kew.
- 1993: MMAT acquires the remaining paintings from the Collection along with the complete set of Mee’s sketchbooks, several notebooks, and assorted memorabilia.
- 1996: Following discussions about the future of the program, MMAT is dissolved and transferred to Kew. The scholarship program is renamed the Margaret Mee Fellowship Programme, working closely with FBMM.
- 2005: The Margaret Mee Fellowship Programme is restricted to artist scholarships, and the FBMM is later renamed the Fundação Flora de Apoio à Botânica.