Border forsythia

Also known as golden bells, border forsythias come in seven different species that spread from East Asia. Only one species is native to southern Europe, Forsythia europaea. Forsythias are part of the olive family (Oleaceae) along with the olive tree.

The Forsythia genus was named after English master gardener William Forsyth. He lived from 1737 to 1804 and managed multiple royal gardens throughout his life as the English monarchy’s head gardener, including the St. James and Kensington Palace gardens. He was also a founding member of the Horticultural Society of London, the precursor to today’s Royal Horticultural Society (RHS). Forsyth missed the introduction of the forsythia as a garden plant to Europe in 1833.

Garden-cultivated border forsythias (Forsythia x intermedia) are all hybrid varieties of two East Asian species, Forsythia suspensa and Forsythia viridissima.

Forsythias are predominantly 6.5-10 feet tall shrubs that initially grow upright before arching over heavily with age. Their growth pattern is basitonic and mesotonic, meaning that shoots emerge from even dormant nodes on older wood at the base and center of the plant, mostly forming long and thin, upright stems. The bark is olive green on younger stems but ochre yellow to gray-yellow on older stems with strikingly large lenticels.

The border forsythia’s leaves are oppositely arranged, 3.15-4.72 inches long and ovate with elongated tips. The edges are serrated and the leaf blade mostly light to fresh green in color. These deciduous leaves sometimes take on a yellow to purple color in fall in sunny locations with dry and nutrient-poor soil.

The numerous flowers mostly appear from mid March depending on the weather. These yellow bells mostly have four petals and measure around 1.18 inches in diameter. They appear across almost the full length of the stems, on wood from the previous year and older wood as well as short side branches. Two to three year old shoots bear the most flowers. From an ecological perspective, border forsythias are not a first choice for gardening as most insects cannot do much with their flowers. They don’t provide bees with nectar or useable pollen, for example.

Most hybrid forsythia varieties are sterile so produce very little fruit. The variety “Beatrix Farrand” fruits reliably: it forms hard, brown capsule fruits after flowering.

Border forsythias flower most generously in full sun. Flowering is considerably less impressive in partial to full shade and the shrub’s crown will not be nearly as dense.

Border forsythias have few requirements when it comes to soil quality. They grow in all acidic to alkaline, well-draining soil that is not too dry. The leaves sometimes turn yellow if there is a high level of lime. A high humus content has a positive impact on the vitality of this flowering shrub.

Forsythias are mostly available to buy in pots, although are sometimes available as bare root plants. As they are easy to propagate and grow very quickly, they are among the easiest flowering shrubs and are therefore relatively inexpensive.

When planting, ensure that the soil can hold water well. When dealing with poor soil, work in sufficient mature compost and leaf humus then cover the surface of the ground with bark humus after planting the shrub.

Border forsythias do not require regular feeding but should be watered before they dry out in dry summers. In heat and dry soil, their leaves will quickly wilt, and drought has a negative impact on the following year’s flowers. Refrain from working on the soil around the roots, and pluck any weeds growing through the mulch layer by hand. As forsythias struggle with strong root competition, you can generally underplant them with groundcover plants to prevent weed growth.

Border forsythias are flowering shrubs that age and reduce flowering relatively quickly. To retain their floral glory, it’s best to prune border forsythias every year to every three years after flowering from mid to late April with pruning shears to thin out. Remove all branches older than three years or cut them above a young, energetic side shoot. Of the new shoots from the previous year emerging from the base of the shrub, their numbers should not exceed the number of aged branches you have removed.

If a forsythia is not pruned for years and its crown has become misshapen, you can cut it back completely to a stump in spring to encourage energetic young shoots to rebuild the crown.

Forsythias boast a generous amount of yellow flowers in spring. This makes them optically very dominant, so they should be use sparingly and accentuated appropriately in the garden. One single forsythia underplanted with blue bulbs, such as grape hyacinths, will create a much better look than a hedge of free-growing border forsythia at the end of a plot. They should be planted in small groups of no more than three plants. Another challenge is covering the rest of the garden season with other suitable flowering shrubs and perennials for after the forsythia blooms. Border forsythias are hardly noticeable after this, as their shape and foliage fails to impress. These shrubs are therefore very well suited as background planting for perennial beds that take on the role of flower-bearer from mid April.

Low-growing border forsythia varieties such as “Week-End” are also sometimes cultivated in containers thanks to their robust nature. Their very short flowering period in spring doesn’t tend to justify such use and the higher maintenance required as a result.

The three main varieties “Beatrix Farrand”, “Lynwood” and “Spectabilis” are only marginally different. “Beatrix Farrand” boasts the most vigorous growth and forms stocky, slightly stiff-looking shoots with relative large flowers and leaves. “Lynwood” has light yellow flowers that are very bright, while those of the “Spectabilis” variety are more of a dark yellow. “Week-End” is a compact variety with relatively light flowers that only grows to 5 to 6.5 feet tall.

It’s very easy to propagate border forsythias, as hardwood cuttings and cuttings from all varieties tend to root reliably. Hardwood cuttings are preferred for taller varieties, while weaker growers are generally propagated by using slightly woody cuttings in spring.

Border forsythias are really robust and not overly susceptible to disease in sunny locations with sufficiently moist soil. Sometimes, Monilinia may occur in spring, which otherwise usually affects sour cherry and some decorative cherry trees. Cut infected branches out of the crown early and thoroughly. Powdery mildew is also a common fungal parasite but one that does not cause serious damage. When it comes to pests, you can predominantly expect weevils and aphids.