Here in the Pacific Northwest fall is the best time to plant both bamboos and maples.  Cooler temperatures and wetter weather allow plants to establish themselves over the winter before summer heat.  Most people equate spring with planting season, but there are many good reasons to plant in the fall.  In the fall, soils are still warm enough to encourage new root growth.  Roots continue to grow, establishing the fall planted plant up until the soil starts to freeze, although, here in the valleys and coastal areas of the Pacific Northwest our soils seldom freeze.  Fall is also the time that bamboo is setting it’s rhizomes for the next years culm production.  Here in the North West, bamboo is actively producing rhizomes and roots throughout most of the winter.  By the time propagation season begins in February,  rhizomes are loaded with culm buds and fibrous new roots.  Plants that are fall planted will quickly establish new roots in spring and be better equipped to deal with drought,  disease and pests.  Spring planted plants will linger as they try to establish themselves through out the summer, require more irrigation and fertilizing.  There’s more great information from Oregon State University Extension Service here:
http://extension.oregonstate.edu/news/story.php?S_No=941&storyType=garden