by Ken Lain, the mountain gardener
This gorgeous shrub explodes with masses of solar yellow flowers followed by shiny green leaves. Every home should have one for sheer beauty, fall color, and gentle natural care.
Forsythias are a genus of deciduous flowering shrubs that belong to the olive family. These low-maintenance, fast-growing shrubs feature an upright, arching form. They are known for their long branches that fill with brilliant yellow blooms early in the spring. The flowers precede their leaves, which means you get a good look at the blooms with no foliage to block your view.
Bees and butterflies love forsythia, and they provide a cheerful backdrop, border, or centerpiece for any yard. Some smaller forsythia varieties only stand a couple of feet tall with a slightly wider spread, while many larger types can reach 8′ feet in height and spread.
Forsythias are fast-growing shrubs that can grow as much as 24 inches in a year, especially the larger varieties. They are best planted in late fall or early spring while the plants are still dormant, but gardeners in frost-free climates can plant them in winter, as well.
Botanical Name Forsythia x intermedia
Common Name Forsythia, golden bells
Plant Type Deciduous shrub
Mature Size 2–8′ feet tall, depending on the variety
Sun Exposure 6+ hours of sun
Soil Type well-draining soil
Soil pH 5.0–8.0 (acidic to alkaline)
Bloom Time Spring
Flower Color Yellow
Hardiness Zones 5 to 8 (USDA)
Native Area Asia
Forsythia bushes are often used as a living privacy wall summer through autumn because of their dense foliage. They are often used for erosion control on slopes and in foundation plantings. The weeping type, Forsythia suspensa, can even be trained to grow as a vine on a trellis or planted behind a retaining wall and allowed to cascade.
Forsythias are tolerant of poor garden soil, and they are drought tolerant once established. The biggest burden when growing forsythia is to keep these fast-growing shrubs pruned to maintain the desired shape and size. This can be ignored if you like a somewhat wild-looking shrub.
Forsythia bushes grow best with at least 6+ hours of direct sun on most days. If your plant gets less sun than this, it might not produce as many flowers.
Forsythias prefer loose, well-draining soil. They have a good tolerance for both acidic and alkaline pH levels.
Water newly planted Forsythia regularly with a garden hose for at least one month (2 months in Summer). Automatic irrigation systems may not be sufficient initially. Water frequency will vary according to the season, exposure, and plant size.
April – Oct Forsythia should be irrigated 2 x weekly.
Nov – Mar Forsythia should be irrigated 2 x monthly.
Temperature and Humidity
They’re happiest when spring temperatures are between 55 and 70 degrees. Many varieties do not respond well when winter temperatures fall below minus -5 degrees Fahrenheit. Flowering for the following spring may be absent or reduced, then returns to normal flowering a year later.
Spring = 7-4-4 All Purpose Food + Soil Sulfur
Summer = 7-4-4 All Purpose Food + Humic
September = 7-4-4 All Purpose Food
December = 7-4-4 All Purpose Food
There are many varieties within the forsythia genus, offering varying sizes and shapes. Some favorites forsythias include:
- Forsythia ‘Sunrise’ is a compact shrub, growing around 4 to 6 feet tall and wide. Its flower buds can withstand colder winter temperatures than many other forsythia varieties.
- Forsythia ‘Meadowlark’ grows around 7 to 10 feet tall with a similar spread. It’s known for having very few issues with pests and diseases.
- Forsythia ‘Kolgold’ matures at around 4 to 5 feet in height and spread. It sports larger flowers than most forsythia bushes, at roughly 1 inch across.
- Forsythia ‘Lynwood Variety’ has somewhat larger yellow flowers, and the leaves turn an attractive yellow with purple tinges in fall.
- Forsythia ‘Courtasol’ is a dwarf shrub that reaches just 1 to 2 feet tall with a spread of around 1 to 4 feet. It produces profuse light yellow flowers in the early spring.
- Forsythia Suspensa is the pure species known as weeping forsythia. It has drooping branches that can grow as long as 10 feet; they can be trained up a trellis if you wish.
- Forsythia ‘Arnold Dwarf’ is a low-growing, spreading shrub that grows only 2 to 3 feet tall, but spreads nicely. Though it does not flower as profusely as other varieties, it is an excellent ground cover plant for large areas.
- Forsythia ‘New Hampshire Gold’ is an excellent cold-hardy shrub, hardy through zone 3. It grows 4 to 5 feet tall and has attractive red color in the fall.
- Forsythia ‘Northern Sun’ is another good shrub for colder climates (zones 4 and south). It grows 10 feet tall and 9 feet wide, with clear yellow flowers.
If you wish to propagate more forsythia plants, you simply take a stem cutting, root it, and transplant it wherever you want. You also can allow the parent plant to spread on its own. When a branch makes contact with the soil, it will often put down roots on the spot, creating a new shrub.
To root a cutting, take a 4-10″ inch stem after flowering is completing and when the shrub has foliage. Remove the bottom leaves, then plant the cutting in a moistened Seedling Potting Soil. Roots from the buried nodes.
Mist your cuttings daily until the roots are about 1 inch in length, which will take at least a month. Grow the plant in a pot in a controlled outdoor environment for one or two seasons before planting it in a garden location.
If left to their own, forsythia bushes can take on a wild shape as branches shoot out in random directions. Many gardeners prefer this wild look, and annual pruning is by no means mandatory. If you’re happy with your bush’s shape, you can go for several years with no pruning.
If you prefer a neater look, you can prune your bush to be more shapely. Pruning Forsythia is best done after blooming in spring because the following spring’s flowers will bloom on wood produced the previous year. If you prune past the end of July, you run the risk of losing all blooms for the following spring.
Begin by pruning roughly a quarter to a third of the oldest branches, cutting them right down to the ground. This will encourage new growth and a more compact form. Beyond this “renewal” pruning, you can selectively cut newer branches to improve your plant’s overall shape.
Common Pests/ Diseases
Forsythia shrubs can be prone to knobby galls forming along the stems and fungal twig blights. Both problems are easily treated by removing affected branches. Twig blights can be prevented by keeping the plant well pruned to improve air circulation and applying a fungicide like Revitalize.
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