The terroir concept has a high influence on the character of wine produced at Klein Constantia. Soil and climate conditions are ideal for producing grapes with ample fruit flavours.

The farm is situated on the eastern slopes and foothills of Constantiaberg. These soils originate from 600M year old granite and were formed in a period of different climatical conditions than those experienced today. The younger Table Mountain sandstone formations, higher on the slopes, do not influence the soils at all. This well drained, fertile decomposed granite with a high clay content ensures good water retention. During the long dry summers of the Cape, enough water will slowly drain back into the vineyards to ensure an efficient leaf canopy and proper ripening of the fruit.

The soil forms on Klein Constantia can be divided mainly between the deep fertile Oakleaf soil and the more dry Glenrosa with a saprolite subsoil. Normally the Oakleaf soil consists of a dark organic rich topsoil of 30-40 cm on top of a deep yellow or red neocutanic subsoil. Lower on the slopes, close to the valley floors, the Oakleaf changes to Tukulu soil which is closely related to the Oakleaf soils. The only difference is signs of short periods of wetness in the deeper soil profiles. Both these soils can be red or yellow in colour.

The Glenrosa soil is more gravelly and yellow coloured topsoil, with weakly weathered subsoil and therefore dries out more quickly. This soil form occurs on the higher slopes of the farm and is less fertile than the Oakleaf soils.