|Pruning tolerance:||High, can be grown as a cutback shrub.|
|Forcing:||Branches can be forced from mid-winter until bloom.|
Forsythia is both the common name and botanical name of a plant genus belonging to the Oleaceae (Olive family). It is named after William Forsyth, and comprises six species of deciduous shrubs to 3–6 m tall, mostly native to Asia, but one native to southeastern Europe.
The leaves are opposite, usually simple but sometimes trifoliate with a basal pair of small leaflets, and range from 4–12 cm long; the margin is serrated. The flowers are produced in the early spring before the leaves, bright yellow with four petals. The fruit is a dry capsule, containing several winged seeds.
The species are:
- Forsythia europaea, from the Balkans
- Forsythia giraldiana, from northwest China
- Forsythia japonica from Japan
- Forsythia ovata, from Korea
- Forsythia suspensa, from China
- Forsythia viridissima, from China
The hybrids Forsythia × intermedia (F. suspensa × F. viridissima) and Forsythia × variabilis (F. ovata × F. suspensa) have been produced in cultivation.
Forsythias are popular early spring flowering shrubs in gardens and parks. Two are commonly cultivated for ornament, Forsythia × intermedia and Forsythia suspensa. They are both spring flowering shrubs, with yellow flowers. They are grown and prized for being tough, reliable garden plants. Forsythia × intermedia is the more commonly grown, is smaller, has an upright habit, and produces strongly coloured flowers. Forsythia suspensa is a large to very large shrub, can be grown as a weeping shrub on banks, and has paler flowers. Many named garden cultivars can also be found.
Commercial propagation is usually by cuttings, taken from green wood after flowering in late spring to early summer; alternatively, cuttings may be taken between November and February.
Forsythia bloom is frequently used as a phenological indicator for timing pre-emergent herbicides in lawns.
Pests and diseases
- Meloidgyne hapla: Northern Root Knot Nematode
- White Peach Scale: Pseudaulacapsis pentagona
- Four-Lined Plant Bug: Poecilocapsus lineatus
- Twobanded Japanese Weevil: Callirhopalus bifasciatus
- Redheaded Flea Beetle: Systena frontalis
- Twobanded Japanese Weevil: Callirhopalus bifasciatus (on roots)
- Cranshaw, Whitney (2004). Garden Insects of North America. Princeton University Press. pp. 595.
- Pirone, Pascal P.. Diseases & Pests of Ornamental Plants. pp. 264–265.