One of the marvels about Grieg's compositions is his use of a wide range of tonal colours. His genius in this regard shows itself not only in his orchestration techniques but also in the way he uses all the possibilities of the piano.
This past summer, I had the great fortune to attend the International Grieg Society's conference in Copenhagen. Many wonderful presentations were given on various aspects of Grieg, with the main focus on Grieg's connections to Copenhagen. Grieg spent a lot of time in Copenhagen, and like me, felt it to be somewhat of a second home.
One of the most illuminating presentations at the Copenhagen Conference 2011 for me was given by the Norwegian conductor Bjarte Engeset, on orchestration. If you have any interest in learning more about Grieg as orchestrator, I urge you to download the pdf of his talk. As a pianist, I am always trying to hear more orchestrally and to emulate the timbres/colours of other instruments. As mentioned in a previous post, some pianos are more up to this task than others. In any case, Maestro Engeset's research has been hugely inspiring and helpful to me in further developing my understanding of Grieg's use of instrumental colours.