The Heckengäu is a part of the Gäu, a region in the counties of Böblingen, Calw, Ludwigsburg and Enzkreis in the German state of Baden-Württemberg. Part of the landscape in the county of Calw is called Schlehengäu. Hence it is also called the Hecken- und Schlehengäu.
The Heckengäu lies west of the state capital of Stuttgart. It forms an elongated strip of land, over 50 km long, running from Vaihingen an der Enz in the north to Haiterbach in the south, and covers parts of the counties of Böblingen, Calw, Ludwigsburg and the Enzkreis. In the west it borders on the Northern Black Forest and, in the east, on the regions of the Korngäu, Strohgäu and Schönbuch. Together with the Korngäu, Strohgäu and Zabergäu it makes up the Baden-Württemberg Gäu.
The Heckengäu is an agricultural region, characterized by a rolling, heavily farmed landscape (the Gäulandschaft or Gäu landscape). Due to its karstified muschelkalk bedrock, the Heckengäu is a dry, edaphic region. Its typical soils are rendzinas and, in terrain hollows, loess deposits from which brown earths (Parabraunerden) can form. The Heckengäu has karstic topographic features such as dry valleys, dolines, karst springs, pots and washouts (Ausschwemmungen). The Heckengäu is also characterised by juniper heaths and orchards, but most of all by hedges that are grow on rows of fieldstones and are reflected in the name of the region (Hecken = hedges). The sloe hedges typical of the eastern Calw county also give the region there its local name of Schlehengäu.