Various switchgrass (Panicum virgatum) cultivars have been grown under research conditions for biofuel in the Pacific Northwest (PNW) since 2002. We have successfully grown the full maturity range of switchgrass varieties, ranging from Dacotah to Alamo in the warm, irrigated region of the PNW. To date, only one planting of SWG has died from winterkill, this being seeded in early August and not advancing into dormancy in the fall that is typical with early June plantings. Additional research in the PNW is needed to identify other planting windows without stand loss due to winterkill. Dacotah and Nebraska 28, the earliest maturity cultivars easily produce 2 fully headed, nearly anthesis stage biomass crops per season. Intermediate varieties such as Trailblazer, Forestburg, Cave-in-Rock, Blackwell and Shawnee will produce 2 excellent biomass harvests with one taken near anthesis and the other harvest slightly less mature. The lowland varieties, Kanlow and Alamo respond very differently in our conditions. Kanlow will provide 2 excellent harvests per season but neither will reach full heading. Alamo often provides only a single good cutting per season and is the last variety to transition into fall dormancy in mid-October. Early maturing upland switchgrasses transitioned into fall dormancy in late September. Intermediate upland varieties transition about 2 weeks later than early varieties with the late, lowland varieties transitioning into fall dormancy last. Biomass yields and quality will be compared among a full range of switchgrass variety maturities grown in the PNW.