No, you can't breed a Roserade with a Geodude, because they are not in the same Egg Group. Roserade is in the Fairy and Plant egg group but Geodude is in the Mineral egg group.
For more info on breeding go to this link--http://pokemondb.net/mechanics/breeding
If you breed a Male Pokemon and a Female Pokemon that are in the same egg group you will be able to breed, because they are not in the same egg group, they will NOT make any eggs.
Hope this helps =P