There are a couple other gardens that are worth visiting if you are in the Salem area in Spring, One of our highlight's in 2010 was the Oregon Garden in Silverton it was beautiful at bloom time, they had a huge selection of mature Japanese Maples and unique trees I have never heard of (Monkey Puzzle Tree) but I think my favorite part of there gardens was the Conifers, from what I remember they have one of the best collections in the US and there landscaping with them really influenced a lot of what I did at home, I never realized that Conifers came in so many different colors and textures until seeing them up close. The bright blue Spruces and Spring blooming Red and Pink maples put on a nice show together.
The 2nd would be Brooks Garden in Salem they specialize in Peonies but had quite a few historics for sell and the landscaping was great another garden with mature conifers, mixed with Roses, Iris, and Peonies worth a stop to walk there show beds.