Extension Educator, Horticulture
Soon shrubs that have been languishing in obscurity for a year will explode into torches of bright yellow flowers. What would spring be without the vibrant blooms of forsythia?
As the forsythia bloom you will get an overwhelming urge to possess one. Keep in mind that forsythia are pretty much a one season plant. They shout out one big hurrah in spring then the rest of the season they are just another big green shrub. A forsythia is like a gangly teenager tripping over his feet with every movement. Forsythias can reach 10 feet tall depending on the cultivar and species. The branches may be upright and arching all on the same shrub and, as Michael Dirr described them in his book Manual of Woody Landscape Plants, "They look like the roots were stuck in an electric socket."
Not much color variety in forsythia flowers, just different shades of yellow. What is called the white forsythia is really another species, Abeliophyllum distichum, which blooms about the same time as forsythia and has many of the same characteristics.
The best placement for forsythias are in a shrub border, mass planting or bank side planting. They are just way too large, wild and unruly for foundation plantings so resist the temptation.
Unfortunately a harsh winter can eliminate the forsythias only hurrah. It is common to see forsythia bloom just on the bottom of the shrub where the flower buds were protected by snow. The best way to insure a good flower show is to plant cold hardy cultivars.
There are many, many different cultivars of hybrid forsythias. I asked Gary Kling, professor with the U of I Department of Natural Resources and Environmental Sciences what some of his recommended cultivars are. There are other nice cultivars but these are some he has observed to be quality plants.
'Beatrix Farrand' is reported to bear numerous large flowers 1-1/2 to 2 inches across. It can get quite large at 8 to 10 feet tall and wide.
'Lynwood' also listed as 'Lynwood Gold' has been around since 1935. It continues to be a quality cultivar for its reliable flowering along the stems. Its habit is more upright than other forsythias. The flowers are not quite as vibrant as 'Beatrix Farrand'.
If an 8-10 foot shrub is just a bit too big, you may want to consider 'Gold Tide' also listed at 'Courtasol'. 'Gold Tide' is a compact shrub/ groundcover at 1-1/2 feet tall and 5 feet wide. The flowers are light yellow on arching stems.
In particularly cold, windswept areas synonymous with rural areas, you may want to seek out 'New Hampshire Gold' or 'Northern Gold'. 'New Hampshire Gold' is as its namesake implies. It was developed in New Hampshire and still bloomed all along the stems after –33°F. Shrub height is a bit shorter than others at five feet tall. 'Northern Gold' has golden yellow flowers. It was developed in Canada and shows flower bud hardiness to –30°F and lower. Other cold hardy cultivars include 'Meadowlark' and 'Northern Sun'.
To keep forsythias looking as good as possible and flowering well, they should be pruned every few years by the renewal method. Each spring after flowering, use loppers to prune out the largest stems to the ground to stimulate new growth from the crown and remaining stems. The remaining stems can then be shortened to shape.
It is important to prune forsythia after they bloom. Forsythia like other early blooming shrubs develop their flower buds during the summer and fall of the previous year, also called "blooming on old wood." Pruning these shrubs in late summer, fall or early spring will remove the flower buds and therefore the flowers.
Forsythia can add a bit of sunshine to your landscape.