Hardy in U.S. Department of Agriculture plant hardiness zones 5 through 8, weeping forsythia (Forsythia suspensa var. sieboldi) has a fountain-like appearance with graceful, trailing stems. When the stems touch the ground, they may set roots and form new plants or offsets. Weeping forsythia flowers have a golden color that is not as bright as other forsythia flowers, and its leaves are dark green. This drought-tolerant shrub grows up up to 10 feet high and 15 feet wide, and makes an attractive trailing plant for hills and slopes.
Greenstem forsythia (Forsythia viridissima) is an upright shrub that grows up to 10 feet high and 10 feet wide. Hardy in USDA zones 5 through 9, this forsythia has greenish yellow flowers and serrated green leaves. Forsythia viridissima var. koreana “Kumson” grows up to 10 feet high and 7 feet wide, and has dark green leaves with silver veins. It grows in slightly cooler USDA zones 4 through 8. At only 1 foot high and 3 feet wide, low-growing “Bronxensis” makes a good border or groundcover. It has light yellow flowers and thrives in USDA zones 6 through 8.
Border forsythia (Forsythia x intermedia) is a hybrid of weeping forsythia and greenstem forsythia (Forsythia viridissima). Many cultivars, including “Lynwood Gold,” thrive in USDA zones 4 through 8. This cultivar grows up to 10 feet tall and 12 feet wide, and has bright yellow flowers and green leaves that turn purplish in the fall. “Fiesta” has a compact, mounded shape and grows up to 2 to 3 feet high and 4 feet wide. Hardy in USDA zones 5 through 8, its variegated leaves have dark green edges and creamy centers.
You can choose from a variety of other forsythia shrubs, such as early forsythia (Forsythia ovata), which has bright yellow flowers in early spring. It grows up to 6 feet tall and 6 feet wide, and thrives in USDA zones 5 through 7. Other hybrids include cold-hardy Forsythia x “New Hampshire Gold,” which has maroon leaves in the fall. It grows up to 5 feet high and 5 feet wide. Forsythia x “Meadowlark” grows up to 10 feet high and 10 feet wide. Both hybrids have arching growth habits and are hardy in USDA zones 3 through 8.