The forsythia is one of the first splashes of springtime color in many yards in the northern United States and has become a landscape staple throughout New England. Its bright yellow blossoms light up the yard, mirroring the golden sun above. They provide a thick screen between neighboring yards and a secure nesting area for several species of birds. The forsythia is very cold-hardy and durable. Its prolific root system enables it to withstand droughts as well as any northern plant. To get the best blossoms year after year, however, one must know how to prune the forsythia properly.
Choosing the right time to prune the forsythia is the most important aspect of preserving the blossoms for the following year. If you prune too late in the year, you'll be removing next year's flowers before they have a chance to bloom. The spring-time forsythia erupts in thousands of little bright yellow flowers along the length of its branches early in the spring. The flowers come out even before the leaves do. The flowers will cover the new growth on the outside of the forsythia bush, leaving the older growth inside more bare. This gives the observant gardener a clue about when to prune.
Since the flowers appear on new growth from the previous year, pruning off this year's new growth means no flowers next year. Therefore, a forsythia must be pruned just after it has finished blossoming, but before it has had a chance to add to the growth of its branches. As soon as the flowers begin to fade, break out the pruning shears for the forsythia.
There are two main types of pruning that can be done for the forsythia. The first is to remove large old growth that has become damaged or has grown in directions that you don't want the plant to go. This should be done very sparingly since you are removing a significant portion of the plant with each old growth branch removed. You should not take more than about fifteen percent of the old growth stalks in any one season. This allows a regular cycling of old growth for new, and keeps the forsythia under control. Some people prefer large spreading forsythia bushes and the don't remove the old growth at all. This is fine, but leaves the bush vulnerable to breakage from heavy winter snows since the older thicker branches are much less flexible and resilient than younger growth.
The send type of pruning for a forsythia is to shape the plant. This is done by trimming the newer growth around the perimeter and top of the plant. This type of pruning must be done immediately after the blossoms fade in the early spring. If you do it later, you'll have few or no flowers for the next season. Small branches can be clipped away either with pruning shears, hand clippers, or even an electric pruner. This outer growth is mostly smaller diameter and easier to cut. Some people prefer a small well-controlled forsythia with shorter branches that remain upright. To achieve this, the pruning must be fairly severe and the plant should be cut back every couple of years, since this is a significant stress on the plant, it should be given at least a year to recover between severe prunings.
Others prefer a more traditional large bush forsythia. These need to be pruned more lightly, just enough to keep them from getting out of control. Light outer growth can be trimmed, again right after the spring flowers fade. A light trimming all around the perimeter of the plant can keep it confined to a certain size. Left completely unpruned, A forsythia will extend itself almost indefinitely with branches above ground and with new plants that grow around its edges.
Forsythia bushes propagate by allowing their branches to take root where ever they touch down. Since young forsythia branches are light and flexible, they tend to droop down toward the ground all around the plant's perimeter. As a result, new bushes may take root anywhere along the outer circle of the main forsythia bush. These can either be clipped off at ground level, or they can be dug up and transplanted to add even more forsythia bushes to your yard. Since they do form along the drip line of the main forsythia bush, be aware that their roots will almost certainly be well intertwined with the roots of the older plant and in some cases they may have even fused together. Don't be afraid to simply cut straight through them as long as you get a decent length of roots for the new plant and are only taking offshoots from one or two areas around a large older forsythia. Forsythias are very tough and hardy and it is difficult to do them long term damage with just one intrusion, but use common sense.
With proper care, a forsythia bush will last just about forever, and will even provide the homeowner will new forsythia bushes that can be replanted elsewhere in the yard or even given away to family and friends to add the bright springtime color to their yards. I like to think of forsythia gifting as spreading sunshine because fo the bright golden yellow flowers that awake with the springtime sun.