I always look forward to an explosion of yellow forsythia blooms every spring and the mass of color can be quite dramatic. They are often the first of the spring blooming deciduous shrubs, and after a hard winter they are very welcome. They also signal all the spring garden chores are imminent. Weeding, preparing ground and pruning are just a few.
Forsythia should be pruned shortly after blooms fade. Unfortunately, that often doesn’t take long. The mass of yellow only lasts a couple weeks, so enjoy it while it’s here.
Forsythias (Forsythia intermedia) grow best in moist but well drained soil. Prolonged periods of wet soils stress the plants. Drought can sometimes be a problem in mid-summer, particularly in southern climates.
Flowering will be more dramatic if these shrubs are allowed to grow in a natural, semi-wild state. They can be formed into a hedge but the bloom will suffer. Regular thinning is necessary to produce strong new stems and more flowers. Forsythia only blooms on one-year-old wood.
Forsythias grow to be large shrubs and a common problem is placing them too close together. They can easily overpower some of the other landscape plants. They’ll compete with each other too and the result is spindly growth. They are best used on property borders or as accent plants and should be allowed to retain a somewhat wild flowing shape, thinning out the weak stems.
Periodically renewal pruning (cutting all stems down to the ground) is necessary to retain vigorous shoots which produce more flowers. You should never do this in the fall. In fact, avoid any forsythia pruning past mid-spring. That way you still have ample growing season to generate plenty of young wood. One reason I like them as an ornamental is that they are non-invasive. I’ve rarely encountered them in areas where they were not actually planted.
These shrubs need full sunlight to bloom. Most sources recommend at least six hours of sun. Sometimes landscape trees shade them enough to suppress flowering and shrubs should either be moved or removed. If plants are large bloom might have to be sacrificed for a year. Forsythias always should be moved when dormant and severely pruned when moved.
Sometimes harsh winters can severely affect forsythia bloom. Plants are hardy to zone 4 but often bloom is spotty. I remember many years growing up in Maine where forsythias wouldn’t flower above the snow level, so they often were spectacular following winters with deep snow. During relatively open winters they sometimes never bloomed at all.
Forsythia flowers are pretty in landscapes and table vases. They also add color to a salad. Many sources recommend them, as they are quite pleasing to the eye. I’ve also seen simple recipes for making forsythia flower syrup. While the flowers are edible and have a delicate aroma, they are on the bitter side. Forsythias aren’t on my consumption list despite the history of Asian medicinal use of several forsythia species.
During the bulk of the season these shrubs aren’t spectacular. Some may even wonder why folks plant them. Forsythias only bloom for a week or two and then only if you don’t manicure them much. That said, they sure ring in spring.
Ted Manzer teaches agriculture at Northeastern High School.