The Columbia Basin is between the Cascades and the Rockies and North of the Great Basin.
Columbia and Snake River Valleys: 120- to 200-day season; hot days, warm nights; length of season fairly well defined. In areas along the Columbia River, where the growing season approaches or exceeds 120 days, planting dates can be moved up to early May. For gardens in lower-elevation areas along the Columbia, heat and steady winds create problems for gardeners trying to establish fruit and vegetable plantings. Frequent, light watering is the only way to keep seedlings from drying out.
The Columbia Plateau 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.
The Snake River Plane is a good agricultural area with fertile soils and ample available water. Sugar beets, potatoes, alfalfa, small grains, and vegetables are the main crops.
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.
This paper by Oregon State University, includes information about gardening in Central and Eastern Oregon on the last two pages.