La Vigna di Iseppo is a biodynamic winery in the town of Premaor di Miane in the province of Treviso, about halfway between Valdobbiadene and Conegliano. They are one of the oldest producers of commercial Prosecco in the area, and the oldest continuous producers of Col Fondo bottlings. They've never used herbicides or pesticides in their steeply terraced vineyards, and all the harvesting is done by hand. In an effort to utilize even less copper and sulfur, homeopathic herbal sprays are used, such as one made with stinging nettles.
The 'Sui Lieviti' finishes its fermentation in the bottle. No cane sugar is used, just unfermented grape juice from grapes left to raisinate in the same vineyard. After secondary fermentation, the yeast is not collected in the neck of the bottle, frozen and then disgorged (as is common in Champagne and other sparkling wine regions of the world). Instead, it is allowed to remain in the bottle, making the resulting wine a bit cloudy. This lees-aged, bottle-fermented, undisgorged Prosecco is made from Glera and Verdiso. The lees and sediment are supposedly an aid to digestion and often this style is thought to combine better with food. Verdiso is grown primarily in province of Treviso and is a permitted variety in the sparkling wine DOC of Prosecco. To be used in Prosecco, the wine must be at least 85% Glera with Verdiso permitted to fill in the remaining 15% of the blend. Other varieties are permitted as well but La Vigna di Iseppo prizes Verdiso, which is generally found at the highest parts of their vineyard.