Not sure - most of the experiments have been with vegetables. Aspirin, sprayed as a solution, does improve growth and yield for the nightshades such as tomatoes, but whether it would be good for a Camellia is unknown. Certainly, aspirin is not good for all plants. Some info here https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/aspirin-for-plant-growth.htm