Forsythia x intermedia

Border forsythia is a fast-growing, flowering, deciduous perennial shrub in the olive family (Oleaceae). Border forsythia is an artificial hybrid between weeping forsythia (F. suspensa) and greenstem forsythia (F. viridissima), with the species epithet, × intermedia, referring to the plant’s characteristics being intermediate between those of the parents. It has many available cultivars. 

Border forsythia is easy to grow and does best in loose, medium-moisture, well-drained soils and in full sun to partial shade, although siting it in full sun will produce more flowers earlier in the spring. The plant matures to 8 to 10 feet high and 10 to 12 feet wide, but it can be pruned to keep the shrub's growth under control. Pruning should be done on the oldest stems immediately after spring flowering; if done after mid-July, you will likely remove flower buds for the following spring because flowers appear on old growth. Forsythia is a forgiving plant and tolerates average to poor garden soils, pollution and urban conditions, salt and drought. The shrub is winter hardy, but colder winters and temperatures below -5 degrees F may retard flower development because of the impact of winter temperatures or a late freeze on unopened buds. The plant is easily transplanted.

The plant has a fountain-like form and is noted for its brilliant and abundant blooms of yellow flowers in early spring before the leaves on its long arching stems appear.

Plant border forsythia as a border, hedge or in a mass planting for spectacular early color. Use it in a cutting garden or on a slope or bank where suitable choices are limited.

Quick ID Hints:

• Leaves are lanceolate, toothed, with a gland at apex.

• Branches are square, four-ridged, brown.

• Flowers are yellow, bell-shaped, with four petals.

Diseases, Insect Pests and Other Plant Problems: Relatively pest- and disease-free; however, there is some susceptibility to leaf spot, crown gall and dieback. Watch for spider mites, aphids, four-lined plant bug, Japanese weevil and northern root-knot nematode. The plant can be occasionally damaged by deer and may develop suckers. 

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.

More information on Forsythia.