From Woody Cut Stems for Growers and Florists: Production and
Post-Harvest Handling of Branches for Flowers, Fruit, and Foliage

Forsythia

forsythia, golden bells

Why You Should Grow It

Forsythia is easy to grow and may be the easiest species to force. They are one of the top ten woody cut flowers, since their vibrant yellow flowers are some of the earliest to bloom. Many growers are also using cultivars with variegated foliage, and using species forms in fall, when the leaves turn blood purple. Dutch studies have shown that dormant cut stems can be held for months.

Why You Shouldn’t

Markets may already be flooded, since this cut is so popular and easy to grow. It is difficult to grow forsythia in areas often hit by late freezes.

Species and Cultivars

Forsythia ‘Arnold Dwarf’. Hybrid of F. xintermedia and F. japonica. Not really dwarf but more compact than most; grows about 4 feet (1.2 m) tall and takes longer to flower than F. xintermedia hybrids. Dirr states flower production begins when plants are five to six years old.

Forsythia xintermedia
, forsythia, golden bells.
 The most commonly used species, F. xintermedia is a hybrid between F. suspensa, a naturally weeping form, and F. viridissima, an upright form. This explains the presence of upright, arching and weeping stems on a single plant. All forsythias bear flowers in varying shades of yellow. When purchasing plants, bear in mind that cultivars are often inaccurately labeled.

‘Arnold Brilliant’. Poor producer of harvestable stems. Difficult to locate.
‘Beatrix Farrand’. Produces lots of large flowers but fewer stems than ‘Lynwood’ and blooms slightly later. Most canes grow upright, though some weep. Flower buds are less cold hardy.
‘Karl Sax’. Golden yellow flowers, slightly smaller than ‘Beatrix Farrand’.
‘Lynwood’. Also known as ‘Lynwood Gold’, this is the most common cultivar for landscape purposes. It seems to be the most prolific producer (see “Research”). It is an upright grower with numerous flowers per stem.
Spectabilis’. Stiff, upright growth habit. This is the most common cultivar grown in the Netherlands. Richard E. Bir and Joseph L. Conner, working in North Carolina, found that this cultivar produced lots of fall flowers, which decreased spring production. Flowers buds are more cold hardy, however.
‘Spring Glory’. Pale yellow flowers open about one week before ‘Lynwood’. Plants branch more but produce fewer stems (see “Research”). May be better for warmer climates (Zones 7 to 8).
‘Vitellina’. Small flowers, upright habit.

Forsythia ovata
, early forsythia.
 This species grows 4 to 6 feet (1.2 to 2 m) tall with an upright habit. Flowers are slightly smaller, but plants bloom earlier and are more cold hardy (Zones 4 to 7) than F. xintermedia. Cultivars include ‘Meadowlark’, ‘New Hampshire Gold’, ‘Northern Gold’, ‘Northern Sun’, ‘Ottawa’, ‘Robusta’, ‘Sunrise’, and ‘Vermont Sun’.

For foliage. Variegated forms are best for foliage sales Forsythia xintermedia cultivars include ‘Fiesta’, ‘Goldleaf’, ‘Golden Times’, ‘Variegata’ (which is not a strong grower and often reverts to green), and F. koreana (also known as F. viridissima var. koreana) ‘Kumson’ and ‘Ilgwang’.

Production

General Growth: Forsythia are deciduous shrubs, growing 6 to 10 feet (2 to 3 m) tall. They have upright, arching, and weeping tendencies. They grow best in areas where winter temperatures are cold but not too cold, which can damage the flower bus (Zones 5 to 8). They grow in almost any soil and should be sited in full sun. In early spring, vibrant, bell-shaped yellow flowers open along the stem. Flowers are followed by dark green leaves, which turn various shades of burgundy in fall. Forsythia as a landscape plant is long-lived; it is common to see healthy forsythia planted 50 years ago.

Spacing:
 Generally, plants can be spaced 4 feet (1.2 m) apart or farther. If allowed, lower stems tend to root and grow their own shoots, producing large plants and filling in the space between plants in the row.

Pruning:
 Forsythia produce axillary (lateral) flowers on last year’s wood; the terminal (end) bud is always vegetative (leafy). Forsythia grows with a stool-like habit, branching from ground level. For best flowering of landscape plants, old wood should be pruned immediately after flowering. Early pruning allows more growing time for foliage, and admits more light and greater air circulation. According to Brown and Kirkham, plants pruned annually will be more vigorous. By early fall, next year’s flower buds have already formed on the stem, which is why stems can be cut at that time for later forcing. Often, a few forsythia blooms will open in the fall.

David Jenkins cut plants to ground level with a brush hog or brush-cutting saw every year immediately following harvest, then fertilized with 10-20-20. Other growers, from North Carolina to Washington State, have also had excellent success by coppicing plants after harvest. At Oregon Roses, they have coppiced plants in the past but saw no gain in production by doing this, so they now cut all stems selectively.

To rejuvenate old shrubs, cut all growth to the ground in late winter and early spring.

Pests and diseases:
 Forsythia is rarely bothered by pests.

Harvest and Postharvest

Stage of harvest: Most buyers want to purchase stems cut in tight bud, with no color showing. Homeowners may want to wait until buds have just started to open. For shipping, stems must be cut in bud; open flowers rarely stand up to this challenge. Cutting on a very cold day should be avoided. Some growers cut one-year-old branches, other cut two-year-old stems, since these have more branching and can look fuller in flower. Occasionally, even three-year-old wood is cut. Harvesting can begin as early as November and held for spring sales. If stems are cut later (January), they can be held at 29F (-2C) or forced immediately.

For foliage, cut in summer or fall after foliage has hardened off. (This can be tested easily by cutting branches and placing them in water. If the leaves wilt almost immediately and stay wilted the branches are not yet ready for cutting.)

Expected yields: Bir and Conner found that yields varied from three stems per plant for ‘Arnold Brilliant’ to eighty stems for ‘Lynwood’, after two years of growth (see “Research”). After three years, ‘Lynwood’ produced over 100 stems per plant.

Conditioning: If you’re planning to store the stems for a long time, Will Fulton recommends dipping them in fungicide first. At Oregon Roses, they found that holding stems at 29F (-2C) eliminates the need for fungicides. Two sources (Edwards; Halpin and Mackey) recommend placing stems in deep water for several hours. Stems cut in tight bud benefit from soaking overnight in water or preservative solution (Nowak and Rudnicki).

Several growers cut stems in tight bud, then hold them in water in the cooler for weeks or even months. They pull out stems as required for sales and may force them for a few days in a warm greenhouse before shipping.

Storage and shipping: Hold in water or preservative solution for short-term storage. Stems cut in tight bud can be held dry at 29 to 41F (-2 to 5C). When held dry, stems must be kept in high humidity chambers. Stems are usually sprayed with water, which freezes on the stems, or held in buckets of ice. Stems can be held like this for months.

Joanna Nowak and Ryszard M. Rudnicki recommend holding opening or open flowers for no longer than three to four days. Ship in water or preservative at 41F (5C). Washington State grower Ted Jonkheer wraps stem bases in wet newspaper, then encloses the entire stem in plastic that is actually recycled greenhouse covering. Tall stems are slightly bent to make 4- to 5-foot (1.2- to 1.5-m) long “big sausages” and are shipped without a box.

Vase life: Cut flowers last from six to ten days.

Propagation

Forsythia are incredibly easy to propagate. There have even been reports of cut stems rooting in the vase. Softwood cuttings are slightly easier to propagate than hardwood (Dirr). Seeds germinate more uniformly when held at 41F (5C) for one to two months.

Marketing

Stems are graded by length. North Carolina growers Gary and Sybil Calder use this system:

Stem length                Stems per bunch
1-2 feet (30-60 cm)               20-25
2-3 feet (60-90 cm)               10
4-5 feet (120-150 cm)            10
5+ feet (150+ cm)                 5

Very tall stems, average 6 to 7 feet (2 to 2.1 m) are hard to find and demand premium prices.

Troubleshooting

Short vase life. Forsythia (and most spring flowers) will last longer when held at cooler temperatures. Also try increasing humidity.

Not all flowers on the stem open. Holding stems in high humidity environments, or soaking stems cut in bud, will help to alleviate this problem.

Stems have only a few flower buds. Forsythia stems bear both vegetative (leaf) and reproductive (flower) buds on the stem. Flower buds are slightly less hardy and may be killed by severe cold and late freezes. Harvest stems early and hold in a cold room. If lack of flower buds is an annual problem, consider growing more cold-hardy cultivars or species. When harvesting, look for the fat flower buds: vegetative buds are usually thinner. If flower buds are located only further down the stem, cut longer stems and cut off the vegetative tips.

Landscape Plantings

Forsythia grows quite large, 8 to 10 feet (2.3 to 3 m) tall and 10 to 12 feet (3 to 3.6 m) wide, so plant accordingly. Single plants or groupings of three to five are very effective in spring. Daffodils look good planted underneath and bloom about the same time.

To keep plants blooming, cut back annually just after flowering. Stems grow 4 to 8 feet (1.2 to 2.3 m) in a season. For old, nonproductive plants, cut all stems to the ground just after flowering. (If the plant does not come back from this treatment, it was dying or dead anyway.)

One of Earth’s worst sights is a sheared forsythia. Please do not treat forsythia as a hedge plant. The natural form is gracefully arching, and plants look so much better when allowed to retain their natural shapes. Plus, many of the flower buds are typically removed when pruning forsythia into hedges, resulting in spotty flowering in the spring. Without flowers, forsythia have little to recommend them as landscape plants. Selectively prune out older wood and blooming stems to keep forsythia looking its best.

Uses

Use stems as linear accents. Because of its early bloom time, forsythia is often used by itself or with simple greenery, rather than combining it with other flowers. Make a statement by mixing forsythia with pussy willows (Salix) and red twig dogwoods (Cornus). Foliage can be used as a filler. Forsythia is not suitable for drying.

Other Comments

Forsythia normally live for decades, and we always feel guilty when plants die early. However, because plants are widely available and very inexpensive, forsythia is an excellent candidate to treat as a short-lived or throw-away woody plant. In other words, do not be afraid to “use up” forsythia plants, since they are easily replaced by propagating your own or buying new, cheap plants.

Research

In the 1990s, Bir and Conner in Fletcher, North Carolina, conducted tests using several cultivars of F. xintermedia. They placed plants 10 feet (3 m) apart within the row and fertilized with ammonium nitrate (34-0-0), applying 0.5 ounces (15 g) per plant the first year and 1 ounce (30 g) the next year. They used glyphosate (Round-Up) and hand weeding to maintain plantings. They found that cultivar played a huge part in number of stems harvested. The outstanding cultivar was ‘Lynwood’, with 80 stems collected from each plant after just two years of growth. ‘Arnold Brilliant’ came in a distant seventh place. They noted that ‘Spring Glory’, which finished in second place, flowered a week earlier than ‘Lynwood’.

Number of Forsythia xintermedia stems per plant.

One-gallon plants were planted in spring of 1995. Results of a study conducted in western North Carolina.

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CULTIVAR                       1996                           1997
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‘Arnold Brilliant’               2.7 e*                        3.7 e
‘Beatrix Farrand’              11.7 d                        30.7 cd
‘Farrand Hybrid’               11.0 d                        17.3 de
‘Karl Sax’                        11.3 d                        49.0 c
‘Lynwood’                        79.7 a                        103.0 a
‘Spectabilis’                     29.7 c                         48.3 bc
‘Spring Glory’                  47.0 b                         68.7 b
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* Each letter represents a statistically different degree. In other words, numbers
with an a are distinctly different from those with b, which are distinctly different
from those with c.