His professional specialism in bananas began in 1928, when he was appointed Pathologist for Banana Research at the Imperial College of Tropical Agriculture in Trinidad. His focus was researching the Panama Disease that had affected plantations in the West Indies. His book Green Havoc (1935) describes his investigations. In the same year, he published another book, Diseases of the Banana, which was republished in an expanded edition as Banana Diseases in 1961 and 1972.
While in Trinidad, Wardlaw was also involved with the work of the Low Temperature Research Station, where he was appointed officer-in-chief in 1933, as well as researching various tropical fruits of the region.
In 1940, Wardlaw returned to Britain to serve as Professor of Cryptogamic Botany at the University of Manchester. He held this position until 1958, when he became the George Harrison Professor of Botany, and later Emeritus Professor of Botany in 1966. He was also elected a Fellow of the Royal Society of Edinburgh.
Wardlaw married Jessie Connell in 1928, with whom he had two sons.
- Green Havoc (1935)
- Diseases of the Banana (1935)
- Tropical Fruits and Vegetables: Storage and Transport (1937)
- Phylogeny and Morphogenesis (1952)
- Embryogenesis in Plants (1955)
- Banana Diseases (1961)
- Organisation and Evolution in Plants (1965)
- Morphogenesis in Plants: A Contemporary Study (1968)
- Essays on Form in Plants (1968)
- Cellular Differentiation in Plants, and Other Essays (1969)
- "Prof C. W. Wardlaw: Authority on diseases of the banana". The Times. 18 December 1985.