Taxonomy and Botany of Forsythia Bushes
The plant taxonomy of the forsythia bushes dealt with in this article is Forsythia x intermedia. This is a hybrid of greenstem (F. viridissima) and a weeping type (F. suspensa). The plants are sometimes given the common name, "border forsythias" or, more rarely, "golden bells."
Forsythias are deciduous flowering shrubs belonging to the olive family.
Features of the Plant
Their flowers precede their leaves, which means that you get a really good look at the blooms (there are no leaves to block your view of them). They are fast-growing shrubs with an upright and arching form. The Sunrise cultivar (Forsythia x intermedia 'Sunrise') is more compact than many forsythia shrubs, growing 4 to 6 feet tall with a spread of 3 to 5 feet. By contrast, Forsythia x intermedia 'Meadowlark' grows 8 to 10 feet tall. In between is Forsythia x intermedia 'Northern Gold', at 6 to 8 feet tall. Even more compact than 'Sunrise' is 'Courtasol' (Gold Tide) at 1 to 2 feet in height, with a spread of 1 to 4 feet.
One knock against this shrub is that it is a one-hit wonder, providing great color while in bloom in early spring but little else for the rest of the year. Admittedly, one would not grow it for its leaves alone, as there is nothing remarkable about their shape or color. Nor are they known for their fall color, although forsythias will sometimes surprise you with nice purplish leaves in autumn.
If you were consistent in denying plants a spot in your landscape based on this objection, however, you would end up missing out on some of the most magnificent specimens of the landscaping world.
For pruning information, see below under "When to Prune Forsythia Bushes." If left to their own devices, forsythia plants take on a rather wild-looking shape, as branches shoot out this way and that.
Most people prefer this wild look, pruning forsythia bushes only sparingly. Through regular pruning, you can shape forsythia bushes to conform to a more regular shape if you so choose.
Even if you do not prune your shrub regularly, you may wish to keep an eye on its spread, at least. For, when one of the branches makes contact with the soil, there is a good chance that it will put down roots on the spot. Such rooting will create a new shrub. You can look at this offspring of the original shrub as either a bonus or an intruder, depending on your perspective:
- It is a bonus if you wish to gain more plants, because you can simply cut the branch that rooted (thereby severing ties with the parent plant), dig up the offspring by the roots, and transplant it wherever you wish. Or simply leave it alone if you want a bigger display and have sufficient space.
- But it is an intruder if you have a small yard and prefer well-behaved plants that do not spread on their own.
Sun and Soil Needs, Growing Zones, Origin
Forsythia plants grow best in full sun and a well-drained soil. But these tough plants show some tolerance of clay soils, too. Water new transplants well to get them established; thereafter, water needs are moderate.
They are hardy to USDA plant hardiness zone 5 and grow well as far south as zone 8. F. suspensa and most other species are native to the Far East.
When to Prune Forsythia Bushes
Pruning of forsythia bushes is best done just after they have finished putting on their flower display in spring, because they bloom on the prior year's growth. If you prune them either too late or too early, you could lose flower buds and end up with a poor display. Begin by pruning 1/4 to 1/3 of oldest branches, cutting them right down to the ground. This will encourage new growth and a more compact form. Beyond this "renewal" or "rejuvenation" pruning, you can also selectively cut newer branches in order to improve upon the overall shape of your forsythia plants. [Note: Some authors draw a distinction between rejuvenation and renewal pruning, reserving the former term for a more drastic operation, whereby the entire plant is cut right down to the ground.]
Remember that annual pruning is by no means mandatory.
If you are happy with your forsythia shrubs as they are, you may wish to go several years between prunings. Note also that there is an additional incentive for pruning forsythia shrubs just after their spring blooms start to fade, beyond wishing not to interrupt their blooming cycle. This is the time when it is easiest to tell the newer branches apart from the older. Only the older branches will have blooms. The first-year branches will not have any yet, so you have a graphic reminder to avoid pruning them (it is the growth of these fresh, new branches that you want to foster).
Uses in Landscape Design
Border forsythias, as the name suggests, are often used to define property boundaries. They can be grown along a fence (to dress it up) or planted to form a border all on their own. These beautiful flowering shrubs are also often used as a "living wall" privacy fence for summer and fall, after they have fully leafed out. In addition, they can be used as specimens for spring, for erosion control on slopes, and in foundation plantings. The weeping type (F. suspensa) can be trained to grow as a vine on a trellis or planted behind a retaining wall and allowed to cascade over the side.
Here is a more novel use for the plants: You can force forsythia by cutting branches and bringing them indoors in late winter. Like forcing pussy willows, this is a great way for the impatient to gain an early taste of springtime.