His prime plots of land are in the top due south-facing Niederberg Helden vineyard of Lieser.
Though just a few hundred metres from his father's Brauneberg vineyards, the heavy thicker set grey/blue slate of the Helden vineyard produces heavier wines that sometimes require more initial bottle age before showing their true colours.
Rigorous work in the vineyard and microscopic attention to detail in his cellars, guarantee a consistent production of good wines in poor years and outstanding wines in great years. In fact, Thomas can regularly claim to have the Mosel's lowest yields.
Since 2004, Thomas has been exploiting some vines in the famous Brauneberger Juffer Sonnenuhr vineyard, given to him by his father Wilhelm Haag of the Fritz Haag estate.