There is a superb Japanese Garden in Portland. It is a little hard to get to. Here's how I do it:
Check the website for times that it's open.
If you've come this far, there are two other things to see: The Zoo itself and the International Rose Test Garden, which is where they try out new hybrids. The directions above tell you how to find the Zoo. The bus to the Japanese Garden also goes to the Rose Gardenin fact, it's right across the street. However, in October there's not much to see at the Rose garden.