Greenstem forsythia (Forsythia viridissima 'Bronxensis')
Discover Forsythia viridissima 'Bronxensis', a low-spreading Greenstem forsythia perfect for ground cover in USDA Zones 6-8.
Complete Plant Information
Overview
Forsythia viridissima ‘Bronxensis’, commonly known as Greenstem forsythia, offers a unique, low-growing alternative to the standard, towering forsythia shrubs. This cultivar is highly valued for its dense, spreading habit, making it an exceptional performer when ground coverage or bank stabilization is required. It brings reliable, bright yellow color to the garden early in spring, often signaling the true beginning of the growing season.
Unlike many of its relatives, Forsythia viridissima ‘Bronxensis’ remains exceptionally compact, seldom exceeding one foot in height while spreading up to three feet wide. This smaller stature allows for flexible use in diverse landscape roles where height restrictions are necessary. As a tough, low-maintenance plant, Greenstem forsythia tolerates less-than-ideal conditions, including urban pollution.
The cultural name ‘Bronxensis’ traces back to its origins as a seedling discovered at the Bronx Botanical Garden in 1939, highlighting its successful adaptation to varied North American environments within USDA Zones 6 through 8. Its dense foliage and durable nature ensure year-round interest even when it is not displaying its signature bloom.
Fast Facts
- Plant Family: Oleaceae
- Plant Type: Deciduous shrub
- Hardiness Zones: USDA Zones 6-8
- Size at Maturity:
- Height: 0.75-1 ft
- Spread: 2-3 ft
- Bloom Time: March to April
- Bloom Description: Yellow
- Sun Exposure: Full sun to part shade
- Water Needs: Medium
- Maintenance Level: Low
How to Grow
Greenstem forsythia establishes best when planted in spring or fall, avoiding the stress of summer heat. Locate your Forsythia viridissima ‘Bronxensis’ where it receives full sun for the absolute best flower production, though it will still perform adequately in partial shade. This shrub is easily grown in average, medium moisture, well-drained soils, and exhibits good tolerance for clay soil types.
Watering should be consistent, particularly during the first year as the shrub establishes new roots. Once established, the Greenstem forsythia maintains medium water needs and requires little supplemental irrigation unless prolonged drought occurs. Maintenance is generally low; minimal fertilization is required if the soil is reasonably fertile.
Pruning is straightforward. To maintain its naturally low shape, light shaping can be done immediately after flowering ceases. For a general refresh, established plants may be pruned hard, even to the ground, in alternate years following blooming. Do not prune in late summer or fall, as this removes next year’s flower buds.
Landscape Uses
The compact, spreading nature of Forsythia viridissima ‘Bronxensis’ makes it an ideal choice for applications where height management is key. It functions exceptionally well as an interesting ground cover, effectively suppressing weeds across slopes or banks where foot traffic is minimal. Its architectural spread also makes it suitable for softening the foundations of buildings or providing early color in rock gardens.
Consider grouping Greenstem forsythia in masses for a dramatic early spring display before surrounding spring-blooming bulbs emerge. Because it tolerates poor conditions, it is a reliable choice near sunny areas of open woodland gardens or along utility easements where toughness is paramount.
Due to its early bloom, pair it with later-emerging perennials or shrubs to ensure continuous seasonal interest throughout the landscape. Plants that thrive in similar low-maintenance environments, such as dwarf spiraeas or low-growing junipers, serve as excellent companions once the forsythia foliage matures.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Forsythia viridissima, sometimes commonly called green-stem forsythia, is an upright deciduous shrub that grows to 10’ tall on branches clad with elliptic-oblong to lanceolate leaves (to 6” long) that are toothed above the middle. Genus name honors William Forsyth (1737-1804), Scottish superintendent of the Royal Gardens of Kensington Palace and author, among other works, of A Treatise on the Culture and Management of Fruit Trees which in its day was probably the most widely read work on the subject. Specific epithet means very green. ‘Bronxensis’ is an unusual low, spreading, flat-topped cultivar that grows to only 12” tall but spreads to 24-36” wide, featuring ovate bright green leaves and light yellow flowers.
Tolerances
- Deer
- Clay Soil
- Black Walnut
Potential Problems
This shrub typically encounters no serious insect or disease problems, contributing significantly to its low maintenance rating. The primary concern for Greenstem forsythia relates to bloom timing and temperature fluctuations. Although vegetatively winter hardy enough for USDA Zone 5, the flower buds themselves remain vulnerable. Cold winter temperatures or late spring freezes can damage the buds, resulting in a significantly reduced or absent spring flower display in those specific years if pruning extends into the wrong season.
Frequently Asked Questions
What hardiness zones is Greenstem forsythia suitable for?
Forsythia viridissima ‘Bronxensis’ is reliably hardy in USDA Zones 6 through 8.
How large does Forsythia viridissima ‘Bronxensis’ grow?
This low, spreading cultivar typically reaches a height between 0.75 and 1 foot tall, spreading wider from 2 to 3 feet across.
When does Greenstem forsythia bloom?
This shrub generally flowers early in the season, blooming from March into April with bright yellow blossoms.
What sun exposure does this shrub need?
For the best performance and most abundant flowering, Forsythia viridissima ‘Bronxensis’ prefers full sun, but it tolerates part shade quite well.
Conclusion
The Greenstem forsythia provides exceptional early spring color in a diminutive, spreading package ideal for ground cover and low borders. Its low maintenance requirements and tolerance for clay soil make Forsythia viridissima ‘Bronxensis’ an invaluable addition to challenging garden sites. Ensure you plant this variety where it receives adequate sunlight, and plan any necessary rejuvenating pruning right after flowering finishes.
Propagation Tips
Propagation of this cultivar is generally successful through semi-hardwood cuttings taken during the summer months, typically July or August. Select healthy, one-year-old stems that have begun to stiffen. Cuttings around 4 to 6 inches long work best, with the lower leaves carefully removed. Dipping the base in rooting hormone before planting into a well-drained, moist propagation medium will significantly increase the success rate for developing new Forsythia viridissima ‘Bronxensis’ specimens.
Design Ideas
Utilize the pronounced horizontal habit of the Greenstem forsythia to create living retaining walls along short, gentle slopes. Plant them densely to maximize bank stabilization during heavy rains. Furthermore, plant this low shrub in the foreground of mixed shrub borders, ensuring its bright early flowers are fully visible over a dwarf evergreen hedge or low ornamental grasses that will emerge later in the spring.
