Forsythia Care: Sun, Size, Bloom Time and Pruning

Forsythia is a large early-spring shrub: plant it in full sun, leave room for 8 to 10 feet of height, and prune it only right after it flowers. Clemson describes border forsythia (Forsythia x intermedia), or golden bell, as ushering in spring with vivid golden yellow flowers. Iowa State says forsythias bloom only on the previous year’s growth (old wood), so the timing of any pruning decides whether you get flowers next spring. Our forsythia pruning guide covers the cuts in detail.

Sun

Full sun for maximum flowering

Origin

Asia

Size

8–10 ft tall, 10–12 ft wide (Clemson)

Soil

Fertile, loose, well-drained; tolerates almost any

Blooms on

Previous year's growth (old wood)

Bloom time

Early to mid-April in Iowa (Iowa State)

Prune

Right after flowering

Sun and soil

Clemson says forsythia should be planted in full sun for maximum flowering. Iowa State says it will grow in partial shade, but won’t bloom as heavily.

Soil is forgiving. Clemson says the ideal soil is fertile, loose and well-drained, although forsythia will tolerate almost any soil condition. Iowa State agrees that forsythias adapt to a wide range of soils.

Size and shape

Clemson gives a mature height and spread of 8 to 10 feet tall and 10 to 12 feet wide. Iowa State gives 8 to 10 feet for both height and width for common cultivars, and describes ‘Sunrise’ as a semi-spreading, compact shrub with a mature height and width of 5 feet.

Bloom time and fall color

Iowa State says forsythias in Iowa typically bloom in early to mid-April, and that they bloom only on the previous year’s growth. Clemson says the flowers will last for two or three weeks unless killed by cold. In fall, Clemson says the leaves may turn slightly yellow, maroon or purple, depending upon the cultivar and the amount of sunlight received.

For a cold climate, Iowa State notes that ‘Northern Sun’ will flower after temperatures drop to -30°F.

Pruning forsythia

Because forsythia flowers on old wood, the timing rule is simple. Iowa State says the best time to prune is immediately after flowering, and that pruning anytime from mid-summer until just before bloom will reduce flowering in spring. Clemson adds that pruning should be a thinning out of the older branches at the base of the plant, not a shearing process. Clemson says forsythias are often sheared to make a formal hedge or reduce size, but this detracts from the graceful habit of growth.

For mature shrubs, Iowa State says to remove one-fourth to one-third of the oldest (largest) stems at ground level every other year. Neglected shrubs can be cut back to within 4 to 6 inches of the ground in late winter or early spring and should bloom again in 1 or 2 years. See the pruning guide for the full set.

Pests and diseases

Iowa State says forsythias do not have serious insect or disease pests.

A year of forsythia care

1. Early spring: enjoy the bloom. Two to three weeks, unless cold kills the flowers (Clemson).
2. Right after flowering: prune. Thin older branches at the base (Clemson); remove one-fourth to one-third of the oldest stems every other year (Iowa State).
3. Summer: leave the shears. Pruning from mid-summer until just before bloom reduces next spring’s flowers (Iowa State).
4. Fall: look for color. Slight yellow, maroon or purple, depending on cultivar and light (Clemson).
5. Late winter or early spring: rejuvenate if needed. Cut old, neglected shrubs to 4 to 6 inches (Iowa State).

If you are planning other spring-flowering shrubs, see our lilac guide, which has the same prune-after-bloom rule.