The choir will be performing from 2pm inside the Great Glasshouse. The concert is free.
On St David's Day, Friday, the choir will be giving a concert at the Coleg Sir Gar Graig campus in Llanelli at 12noon.
Cor Meibion Llanelli secretary Fred Elias said: "We thought we'd try something different to a normal St David's Day concert this year. The choir is keen to get involved in all sections of the community, young and old. We are looking forward to performing before the students of Coleg Sir Gar and the visitors to the Botanic Gardens. Performing in the Great Glasshouse at the Botanic is going to be a first for the choir."