Forsythia X Intermedia is commonly known as Border forsythia and is native to China. It is a deciduous shrub that is best grown in zones 5-8. The Border forsythia is a cross between the Forsythia suspensa and the Forsythis viridissima. The blooms are very sensitive to frost. The Forsythia X Intermedia has a rapid growth rate and will reach the height of 8 to 10 feet and a width of 10 to 12 feet. They prefer to be in the full sun but they will do well is partial shade. The bloom color will be faded without sunlight. They are drought tolerant and like to be in loose soil that is well drained but can tolerate being in other conditions.
These fast growing shrubs grow upright and form arching shoots. There is no real shape to the bush because of the shoots. However, the bush can be shaped or at least tamed with pruning if it is so desired. They make for nice flowering borders and screens. To plant them for hedges, make sure they are 4 to 6 feet apart. They also can be trained to grow upright like a small tree if desired. Burning bush shrubs are excellent to plant near the golden beauties for a splash of yellow and red.
This shrub is a popular among landscapers because it is one of the earliest shrubs to bloom in the spring. They bloom in March and April. The bright yellow flower will brighten and yard that is still stuck in winter hibernation. It is said that the deep yellow flowers can even be seen at twilight. The flowers are about 1 ½ inches long. There are four petals to a bloom. They bloom in clusters of 2 to 6 on a square stem. The blooms last for 2 to 3 weeks. If pruning is desired, prune after the blooming period is over. It is only necessary to prune the old branches unless shaping is the intent.
In the summer, the shrub is dominated with medium to dark green leaves. The leaves are 3 to 5 inches long and about ½ inch wide. The shrub holds its color into late fall with the leaves turning from green to yellow-green in color. The healthiest of shrubs will get a tint of purple over its yellow-green leaves.
After pollination, the shrubs may develop little brown suckers. They usually are pest free and require very little maintenance. There best season is the very early spring and their showy yellow flowers will not disappoint especially if placed in key areas of the landscape.