Forsythia ‘Northern Sun’ produces large golden-yellow flowers in very early spring and was selected because the flower buds can survive very cold temperatures (minus 30 degrees Fahrenheit). The arching branches will grow to 10 feet in height and 8 feet across. Tolerant of a variety of soils, this shrub should be grown in full sun for the best flower production. Renewal pruning is recommended to maintain high-quality flower displays over the years. Northern Sun is a hybrid between the very hardy Korean Forsythia ovata and the less hardy Forsythia europaea. The seeds from this cross were planted at the Minnesota Landscape Arboretum in 1957. Unlike other cultivars of forsythia, the flowers on this taxon were never killed by the harsh Minnesota winter weather.