Forsythia species and hybrids are one of the relatively few plant genuses which are lime tolerant and will grow well in any soil conditions. Their name commemorates William Forsyth who was superintendent of the royal gardens at Kensington in the 18th century. They are botanically related to Jasmines and Lilacs and all have yellow flowers either singly or in clusters borne at the joints of the previous year’s growth. Fruit capsules are seldom produced in forsythia in UK gardens because they usually flower before insect pollinators have emerged from winter hibernation and because cross pollination between two separate species is usually necessary.
Forsythia grow in open woodland in E and SE Asia although there is one European species; the little known F. europaea. Forsythia make excellent shrub border plants or they can be grown as freestanding specimens. The best plants at Caerhays are grown up against a wall or trailing down from the top of a bank where one can view the flowers from below. They are extremely tough, hardy plants whose late winter or early spring flowers are tolerant of frost. Some of the Caerhays plants produce a few secondary flowers in November soon after the leaves have dropped. This does not occur every year but seems more evident after a dry summer.
Forsythia need little pruning except perhaps to remove a few older shoots to make room for vigorous new growth shoots as they appear from within the clump. Forsythia like to layer themselves into the ground as the clumps develop and, within reason or as space allows, this is to be encouraged.
F. mandshurica is a relatively new addition to our catalogue and is a suckering plant which helps it spread quickly. It grows only to about 3-4ft and has yellow, orange and then red autumn colour. It flowers very early in the season with large flowers on bare stems.
F. x intermedia ‘Lynwood’ produces a profusion of large rich yellow flowers and is rightly the most popular variety for its overall impact in the garden at a drab time of the year.
Forsythia can be propagated from softwood cuttings in late spring or hardwood cuttings in the cold frame. Blue tits can attack the flowers for their nectar but, with us, the earlier camellias are normally more to their liking.