USDA Hardiness Zone 3
RHS Hardiness Rating H7
In 1935, Karl Sax and Haig Derman at the Arnold Arboretum in Massachusetts attempted to breed a frost-resistent, free-flowering forsythia by crossing the two hardiest species known at the time, F. europaea and F. ovata. Neither of the parents are as floriferous as the familiar garden forms of F. × intermedia and, at the time, none of the Arnold seedlings were considered worth propagating. In 1966 or 1967, however, Dr Harrison Flint, Associate Horticulturalist at the Arboretum, selected one of these plants whose flowers had been unaffected by that season’s harsh winter; this proved hardy in trials at the North and South Dakota State University and was finally introduced to the trade as ‘Meadowlark’ in 1984, nearly fifty years after it was bred (Arnold Arboretum 2018).
‘Meadowlark’ is still considered the hardiest of all forsythias, flowering reliably in USDA hardiness zone 3 (Arnold Arboretum 2018). It makes an untidy shrub to 3 m tall, with dark green leaves. It is sometimes erroneously listed as a clone of F. × intermedia.