The annual forms (Cosmos bipinnatus and C. sulphureus) are half-hardy, which means their seeds must be sown under cover before risk of frost has passed. Having just one year to set seed ...

Cope, F W. 1938. Some factors controlling the yield of young cacao—II. 8th Ann Rep on Cacao Res (Trin.), pp. 4–15. Cope, F W. 1939. Studies in the mechanism of self-incompatibility in cacao-II.