Weingut Gunderloch was founded by Carl Gunderloch in 1890 and is now run by the fifth generation, Agnes and Fritz Hasselbach. The Hasselbachs own vineyards in the famous Roter Hang ("Red Slope"), a strip of vineyards stretching along the river Rhine between the villages of Nackenheim and Nierstein. The red slope got its name from its red soil, which is primarily composed of iron-rich clay and slate. Oxidation of the iron content gives the soil its red hue. This area of vineyards also enjoys a beneficial proximity to the Rhine, creating a mesoclimate of mild days and cool nights throughout the growing season. Ideal conditions for Riesling.
The Gunderloch estate owns 80% of the Nackenheim Rothenberg, their south-east facing grand cru vineyard. The Rothenberg has steep slopes dropping down towards the the big and unhurried Rhine river, which reflects the sunlight and thus provides additional warmth for the grapes to ripen. The clay content in the soil stores the heat and provides further warmth during the night. The Riesling vines in the Rothenberg are between 30 and 35 years old, their roots growing 50 meters deep into the bedrock. The Nierstein Pettenthal, another important vineyard of the Gunderloch estate is a steep vineyard with slightly "younger" vines of 25 years in average.
Gunderloch produces wines from simple QbA Riesling to Trockenbeerenauslese and Eiswein. The edelsüssen (nobly sweet) wines are those Gunderloch is particularly known for. The single vineyard wines from the Nackenheim Rothenberg are usually all sweet, with the exception of "Riesling dry" (which has a slightly more herbal character than its sweet brethren). Gunderloch considers the Nackenheim Rothenberg as its Grand Cru wine. Only the best wines bear the vineyard name on their labels.