The main two towns in the county are Slavonski Brod on the river Sava in the eastern half, and Nova Gradiška in the centre of the western half. The soils range from the diluvial plains in the north to chalk and lime slopes of the hills, down to the alluvial valley of the Sava river. The highest peak is Psunj at 984 metres.
The winegrowing areas of the Brod Posavina counties are part of the larger Slavonia region and consist of two sub-regions:
Slavonski Brod comprising Garčin, Podcrkavlje, Slavonski Brod, Sibinj, Brodski Stupnik, Oriovac, Bukovlje, Klakar, Bebrina, Donji Andrijevci, Vrpolje, Slavonski Šamac, Strizivojna, Gornja Vrba, Oprisavci, Gundinci, Velika Kopanica, Sikirevci;
Nova Gradiška consisting of Nova Gradiška, Nova Kapela, Staro Petrovo Selo, Rešetari, Cernik, Gornji Bogičevci, Dragalić, Okučani, Stara Gradiška, Vrbje, Davor;
Like other parts of Northern Croatia, wine making has been practiced here since pre-roman times. The Romans, especially during Emperor Probus' reign in the 3rd century, greatly increased wine production. Probus himself was from the nearby town of Sirmium. Legend has it that Probus was eventually assasinated by his troops because he made them work on planting vineyards when they did not have a war to fight.
In medieval times, grapes were grown here by everybody. Serfs, free citisens, nobility, even church institutions. The gentle, wavy hills, the minerally and well drained soils, and the moderate continental climate have been extremely suitable for growing many varieties of grapes. The vineyards here have often been thought of as some of the best in Croatia.
Some of the better known winemaking town/village names are Brodski Stupnik, Bukovlje and Oriovac, and Slavonski Brod has a whole suburb called Brodsko Vinogorje (Brod Vineyards).
There are many events linked to grapegrowing and winemaking. St Martin's and St Vincent's days are celebrated pretty much everywhere. Radio Slavonia even organizes an annual Vinobus to take people around the vineyards for St Vincent's day celebrations.
Some of the bigger wine related events are:
Vinkovita, annual wine competition in Bukovlje in middle of January (St Vincent's). Organized by the Winegrowers and winemakers association “Igrač”
Oriovita, annual wine and gastronomy event in Oriovac in June, which includes Fišijada, a competition to make the best traditional Slavonian fish stew. Organized by the Oriovac Wine Association
Stupnička Berba Grožđa - Stupnik Grape Harvest celebration, an evening of wine food and music every September. The 31st one is on September 10, 2016.
Katarinski Sajam in Slavonski Brod in November - running since 1769! A huge agricultural fair that includes a large wine component, as well as brewing and gastronomy judging.
The dominant grape of Brod Posavina county is Graševina, which produces some of its best wines here. In addition there are numerous other sorts, white and red, notably excelent Frankovka.
Sadly, for such a good wine region the tourist boards, chambers of commerce, or town and county web sites contain very little concrete information. Here is the link for the County tourist board