Forsythia viridissima aka Greenstem Forsythia

Forsythia viridissima is known as greenstem forsythia or golden bells. It belongs to the olive family, Oleaceae. Its native range covers southern China and southern Korea. This woody shrub grows in temperate climates. It usually sheds its leaves, though some plants keep part of their foliage. Its main garden feature is its spring display of yellow flowers.

The shrub has several stems and a dense, upright form. Older branches bend outward and give it a spreading shape. NC State gives a garden height and width of 6–10 feet [1.8–3 metres]. RHS lists a smaller height of 5–8 feet [1.5–2.5 metres]. Its spread there is 3–5 feet [1–1.5 metres]. Plants reach full size in five to ten years. Young shoots stay green into their second year or longer. The stems have square sides and clear lenticels. Older bark is rough and grey-brown.

The leaves grow in pairs on opposite sides of each stem. Each leaf is simple, narrow, and pointed at both ends. Leaves reach 4–6 inches long and have green, hairless surfaces. Teeth line the edges above the middle. The leaves can gain purple tones in autumn. Flowers open before the leaves and have four deep lobes. Their petals join at the base to form a short tube. The yellow blooms may have a green tint. They appear alone or in small groups. NC State reports flowering from February or March through April or May. RHS places the main display in April, later than other forsythias. Dry capsules hold several winged seeds.

Grow this shrub in moist soil that drains well. Full sun gives more flowers, though it also accepts partial shade. It grows in clay, loam, sand, or chalk. It accepts acid, neutral, and alkaline soils. It also tolerates poor soil, drought, and urban conditions. Growth is moderate, and care needs are low. NC State lists USDA zones 5–8; RHS rates it H5. Use it in borders, hedges, screens, or foundation beds. Cut flowering stems can bring the spring display indoors. Semi-hardwood cuttings offer a way to raise more plants.

NC State reports no major pest or disease problems. RHS notes honey fungus, forsythia gall, and birds eating buds. No edible uses are recorded by Plants For A Future. That source records Korean medicinal uses for the fruit. The leaves contain phillyrin, whose potency it describes as unknown. NC State lists the plant as non-toxic to cats, dogs, and horses.