Forsythia x intermedia

Forsythia x intermedia

Forsythia, Border Forsythia, or Golden Bells

(Oleaceae - Olive Family)

FEATURES

Form

medium-sized ornamental shrub (sometimes pruned into small tree form)
maturing at about 8' tall by 10' wide, although sometimes larger
upright oval, open, and straggly growth habit in youth quickly becomes an arching rounded, thick, and semi-pendulous growth habit with maturity
rapid growth rate

Culture

full sun to partial shade
prefers moist, well-drained soils in full sun, but is very adaptable to poor soils, rocky soils, dry soils, compacted soils, various soil pHs, drought, heavy pruning, and pollution (and is therefore very urban tolerant)
propagated primarily by rooted stem cuttings
Olive Family, with few disease or pest problems
abundantly available in ball and burlap or container forms
any pruning after mid-July will cause the loss of some floral buds for the following year, including Forsythia grown as a formal hedge
reduced flowering also occurs in shady situations, and vegetative growth becomes more leggy and stretching
when installed or pruned as a specimen plant that has been limbed up into a single- or multi-trunked small tree form, this type of Forsythia must continuously have its basal suckers removed to maintain this growth habit

Foliage

medium green leaves are about 4" long, opposite to sub-opposite, ovate to elliptical, and serrated on the upper half of the leaf blade, with an acuminate tip
fall color is usually chartreuse, but is sometimes a mixture of chartreuse, yellow, red-wine, and purple foliage colors, but is ornamentally ineffective

Flowers

bright yellow, usually from late March to mid-April and effective for one to two weeks
flowers occur in clusters, emerging before the foliage, with the four petals on each flower fused at their base
floral buds are continuously lost when Winter temperatures fall to between -5 to -15 degrees Fahrenheit; below this temperature all floral buds are lost except for those that are below any existing snow line, or except for cultivars noted for their floral bud cold hardiness
opened flowers are not very tolerant of moderate to heavy freezes, and have a wilted yellow-brown appearance with cold exposure

Fruits

Twigs

green when new, becoming olive-brown to yellow-brown with maturity, strongly lenticeled with raised lenticels, and a combination of semi-pendulous and upturned growth habit with age
floral buds occur prominently in the leaf axils, and are somewhat elongated, rather than plump or round; a few may break dormancy during the warm days of Autumn
suckering basal shoots are upright and stout, while twigs on very old branches are thin, short, and much-branched

Trunk

ID Summary

four-petaled showy yellow flowers serve as the ultimate symbol of Spring for many landscapes, but are not bud-hardy reliable in the northernmost portion of its range in severe Winters
leaves are opposite, ovate, serrated on the upper half, and occur on greenish-chartruese stout stems, with prominent floral buds in the leaf axils during the dormant season
growth habit, in a nutshell, is irregular for this rapidly growing, sprawling shrub that has the contradictory juxtaposition of upright basal suckers and pendulous older branches

Function

Spring accent, row planting, group or mass planting, formal or informal hedge, border, entranceway, non-thorny barrier, or embankment shrub; also can be limbed up into small tree form
sometimes improperly used at foundations (where it becomes too large) or pruned into formal hedge or topiary forms (where the need for pruning is frequent, and the shrub becomes leggy and devoid of most of its potential flower buds)

Texture

Assets

Liabilities

Spring flowering may be poor or absent in the Northern part of its range (except when cold-hardy floral bud hybrids are used) due to Winter floral bud kill or late Winter freezes of the opened flowers
spreads very rapidly in lateral growth, often beyond its intended boundaries
growth is often unkempt and straggly, unless judiciously pruned
moderate pruning after mid-June significantly reduces the amount of potential flowering during the following Spring, as floral buds are starting to set by this point

Habitat

with respect to both stem growth and roots, hardiness is from zones 4 to 8 (but floral buds are marginally hardy under true zone 5 conditions of a minimum Winter temperature of -10 to -20 degrees Fahrenheit)
a hybrid of Weeping Forsythia (Forsythia suspensa) and Greenstem Forsythia (Forsythia viridissima), with both parents native to China

Alternates

early Spring-flowering shrubs (Abeliophyllum distichum, Fothergilla gardenii, Hamamelis x intermedia, Pieris japonica, Viburnum carlesii, etc.)
fast-growing and urban-tolerant shrubs (Aronia arbutifolia, Cornus sericea, Salix pupurea, Viburnum dentatum, Weigela florida, etc.)

Variants

Forsythia x intermedia cultivars that are commonly grown today, which differ only slightly in terms of their growth habit, mature height and width, floral density, petal openness, bright shade of yellow, and relatively poor floral bud hardiness, include 'Karl Sax', 'Lynwood Gold', Spectabilis', and 'Spring Glory'
Forsythia x 'Meadowlark' - a hybrid of Forsythia ovata and Forsythia europaea, whose floral buds are hardy to -35 degrees Fahrenheit (to portions of zone 3), nearly as showy in flower as other Forsythia cultivars and having dark green foliage, but with an arching, prostrate, sprawling, unkempt growth habit, needing lots of room, to 9' tall by 12' wide if never pruned; young transplants often do not flower heavily in youth
Forsythia x 'Northern Sun' - similar to 'Meadowlark', except floral buds are hardy to -30 degrees Fahrenheit

NOTES

Translation

Forsythia is named after William Forsyth of 18th century Scotland.
x intermedia translates as "intermediate" because it is a hybrid between Weeping Forsythia (Forsythia suspensa) and Greenstem Forsythia (Forsythia viridissima).

Purpose

Forsythia is one of the first shrubs to flower, in late Winter and early Spring.

Summary

Forsythia x intermedia is a vigorously growing shrub with showy, bright yellow, early Spring flowers emerging before the foliage, often used as a Spring accent or as an informal barrier hedge.