The Columbia Basin is between the Cascades and the Rockies and North of the Great Basin. It includes the areas that drain into the Columbia River including its largest tributary, the Snake River - the Columbia Plateau, the Blue Mountains, and the Snake River Plane.
The Columbia Plateau is an area of Southeast Washington and Northeast Oregon dissected by the Columbia River. It is in the rain shadow of the Cascade Mountains and so the climate is arid with hot, dry summers and cold winters. The annual precipitation increases from Southwest to Northeast. Some areas are extensively cultivated for Winter wheat, particularly to the East where rainfall is greater. Other crops include barley, alfalfa, potatoes, onions, hops, lentils, and dry peas. There are many fruit orchards and vineyards in some areas. Larger Columbia Plateau cities and towns in Washington include Spokane, Davenport, Reardan, Moses Lake, Yakima, Richland, Kennewick, Pasco, Pullman, Richland, Goldendale, Deer Park, and Walla Walla. Cities and towns in Oregon include Hermiston, Hood River, Pendleton, and The Dalles.
The Blue Mountains are primarily in Northeastern Oregon with small areas extending into Southeastern Washington and Western Idaho. The terrain is more open than the Cascade and Rocky Mountains. Summers are warm and dry and Winters cold. There are areas of irrigated agriculture for alfalfa, winter wheat, potatoes, mint, onions, garlic, grass seed. Larger cities and towns in the Blue Mountains include Madras, Redmond, Prineville, La Grande, Baker City, and Enterprise.
The Snake River Plane is an area of low hills and planes surrounding the Snake River stretching from Oregon through Southern Idaho to the Yellowstone Plateau. It has a dry climate with warm summers and cold winters. Because of the fertile soils and available water, much of the valleys bordering the Snake River are used for agriculture, with sugar beets, potatoes, alfalfa, small grains, and vegetables being the main crops. Larger cities in the Snake River Plain include Boise, Nampa, Pocatello, Blackfoot, Idaho Falls, Rexburg, and Twin Falls.
This paper by Oregon State University, includes information about gardening in Central and Eastern Oregon on the last two pages.