| I don't know where, but I can tell you what to ask for: There are several species of "tall" Oenothera. Oenothera hookeri Oenothera biennis is a Eastern NA native and a nice biennial weed. Oenothera elata hookeri is beautiful but I'm not sure it's hardy for zone 6. Oenothera fruticosa has dozens of cultivars, all nice and a bit assertive. Oenothera glazioviana is a favorite. Good retail garden centers should carry one or more of these. Otherwise, they're available (especially the superior hybrids and cultivars) through several mail-order companies. | 
