Just when you don’t think you can stand another minute of bare branches or dead, brown-gray foliage, spring heralds its arrival in a burst of dazzling yellow. All over town, forsythias reassure us that the growing season has finally arrived.
Originally from eastern Asia, where they have been cultivated for centuries, forsythias were collected for western gardens in the early 1800s. Most current garden varieties are hybrids of two species, Forsythia suspensa and F. viridissima. The problem is that the resulting cultivars aren’t reliably hardy in much of Colorado.
Happily plant breeders have been hard at work. ‘Northern Gold’ and ‘Northern Sun’ are both the product of a cross that includes a very hardy (but not very showy) Korean species. The resulting bushes retain the spectacular floral display of their other parentage, and survive down to USDA zone 4, or even 3 with a thick mulch or good snow cover. That’s plenty of hardiness for the Front Range. ‘Meadowlark’ is another cultivar hardy to zone 4.