DOC Do Tejo occupies almost the same large area as VR Tejo, on either side of the River Tagus (Tejo in Portuguese) as it flows gently along in a south-westerly direction towards its estuary at Lisbon. Until recently the DOC was called Ribatejo and the "vinho regional Ribatejano".
Climatic and geological conditions vary greatly throughout the region. A lot of the vines grow, along with huge quantities of vegetables, on the wide, alluvial plain of the Tagus, in soil known as leziria, very fertile and frankly over-productive as far as quality wine is concerned – unless growers commit great attention and time to reducing their crops and pruning back the exuberant vegetation. Many growers deliver to large co-operatives.
Some quality-conscious producers have focussed their attention on the hotter, drier, sandy land to the southern side of the river, to the east of Muge, Almeirim and Salvaterra de Magos, bordering on the Alentejo. Soils here are known as charneca.
On the other side of the Tagus but further north, heading up towards the border with Lisboa region and the foothills of mountains of the Encostas de Aire, the soils are clay-based, and known as bairro. In the west of the Tejo region, around Rio Maior, sea air passes through a gap in mountains, making the climate wetter, windier and cooler.
The DOC regulations allow a fairly wide range of grape varieties, for whites the local Fernão Pires, Alicante Branco, Arinto, Tália, Trincadeira das Pratas and Vital, but also Chardonnay and Sauvignon Blanc, and alongside the traditional red Castelão and Trincadeira it is possible to use Aragonez, Touriga Nacional, Cabernet Sauvignon and Merlot.