Margaret River

The Margaret River Wine Association dates European settlement to Augusta (1830) and Vasse (1841); in the 1840s Elijah Dawson planted a small commercial vineyard at Westbrook near Busselton that served American whalers. In 1955 Harold Olmo of the University of California was invited to report on Western Australian viticulture and pointed to the south-west. John Gladstones of the University of Western Australia followed in 1965 and 1966 with two reports, the second naming Cowaramup–Bramley and Witchcliffe–Forest Grove as suitable.

Tom Cullity planted Vasse Felix in 1967, followed by Moss Wood (1969), Cape Mentelle (1970), Cullen (1971), Sandalford (1972) and Leeuwin Estate, Woodlands and Wrights (1973); by 1980 there were 20 vineyards. An experimental appellation scheme run by the state Department of Agriculture operated from 1978 for about a decade. Gladstones proposed the GI boundary in June 1994, and Margaret River was entered in the register on 30 October 1996.

Wine Australia's guide describes a long, narrow region with ocean on three sides, one of the most geographically isolated wine regions. Down its middle runs the Leeuwin–Naturaliste ridge, whose granite bedrock is 150–600 million years old, overlain in places by limestone about two million years old. The soils are mainly deep, well-drained red gravelly loams on granite and gneiss, low in nutrients and with low water-holding capacity, which keeps vine vigour low.

Wine Australia calls the climate the most markedly maritime of any Australian region in terms of rainfall: heavy winter rain, a dry warm summer, little frost or hail, and a low day-night range that gives very even heat accumulation. Growing-season rainfall is 202 mm and the mean January temperature 20.9 °C, with vineyards at 0–234 m. The eastern boundary of the GI follows the 'Gladstones Line' at longitude 115°18′E.

Wine Australia compares the climate overall to Bordeaux in a dry year. It describes Margaret River Cabernet Sauvignon, often blended with Merlot, as medium to full-bodied, with earthy, gravelly notes and ripe cassis and violet aromas, and the Chardonnay, mostly from the Mendoza or Gin Gin clone, as intense and complex with lime-like acidity. Semillon–Sauvignon Blanc blends are crisp and juicy, and proportions, oak and ripeness vary widely between producers. The guide links the long, dry ripening season to Cabernet ripening late into the season, and the absence of phylloxera to vineyards propagated from cuttings of existing vineyards.

Margaret River is a region of the South West Australia zone, with Blackwood Valley, Geographe, Great Southern, Manjimup and Pemberton, and has no registered subregions. In 1999 Gladstones proposed six, Yallingup, Carbunup, Wilyabrup, Treeton, Wallcliffe and Karridale, which are used informally. In 2017 five wineries applied to determine Wilyabrup as a GI; in 2020 the Geographical Indications Committee decided not to make a final determination, citing a lack of agreement on its boundaries and attributes. The five most planted varieties are Cabernet Sauvignon, Sauvignon Blanc, Chardonnay, Semillon and Shiraz, with a fairly even split between red and white. A wine labelled Margaret River needs at least 85% of its grapes from the GI.