Soils of the Columbia Basin are generally alkaline (pH > 7). They may be loess, loam, sandy loam, clay, silt or some combination thereof. Basalt and/or cobble from flood deposits may be present or even predominate.
The native plants of the Columbia Basin are well adapted to our soils. In most cases, the property owner will not need to enrich or amend their soil. Doing so could even harm our shrub-steppe plants. However, knowing the type of soil you have be it coarse or fine, how well it drains, etc., will aid you in selecting those plants that will do best for your situation.
When we visit with you to discuss what you'd like to accomplish with the addition of a Heritage Garden, we can give you an idea of your soil conditions and the plants that would do best. You may want to consider getting a soil analysis performed. Not only will this help determine the makeup of your Heritage Garden, but it could well prove useful in maintaining your lawn, trees, vegetable garden, etc.
Soil Analysis Resources
Learn More About Soil
Soils: Foundation for Life Webinar (source: Soil Science Society of America, https://www.soils.org/)