The soils in the Wairau Valley and the wine-growing districts surrounding Blenheim are primarily free-draining alluvial gravels. The valley is situated between the Richmond Ranges to the north and the Wither Hills to the south, which protect it from extreme weather conditions. These two factors make the valley ideal for viticulture. The climate is usually sunny and warm in summer and autumn, resulting in a long growing season, and the cool night-time sea breezes provide the temperature variation required for good characterful wines. It can also be very dry, and younger vines often require some degree of irrigation. Extensive planting has been undertaken on the river terraces and flood plains on the valley floor, although some wineries are using organic practices to also dry-farm vines on north-facing hill slopes.
