Arrowwood Viburnum (Viburnum dentatum)

Arrowwood viburnum (*Viburnum dentatum*) is a small perennial woody shrub native to the eastern United States and Canada. This shrub is not typically used for ornamental purposes aside from shrub hedges. It has the potential to attract songbirds and white flies.

I. Appearance and Characteristics 

Viburnum dentatum, southern arrowwood or arrowwood viburnum or roughish arrowwood, is a small shrub, native to the eastern United States and Canada from Maine south to northern Florida and eastern Texas.

This native viburnum can grow 3 to 9 feet (1-3 m.) tall with an impressive spread of up to 8 feet (2.4 m.) in width. The multiple stems form an arching crown with numerous suckers joining in the fun over time. The foliage is oval to oblong with gently toothed margins, shiny green above and paler, duller green below. These leaves are 1 ½ to 4 inches (4-10 cm.) in length and are the first spectacle on parade. Foliage turns a rich red, yellow or even reddish purple in fall. The plant produces tiny white flowers in combs. These develop into ¼ inch (.6 cm.) blue-black drupes, which is very attractive to wildlife. A historical piece of Southern Arrowwood information is its use as a medicinal. All parts of the plant were once used in different preparations to assist in healing the body.

Some moth larvae feed on V. dentatum. Known such species include the unsated sallow (or arrowwood sallow; Metaxaglaea inulta) and Phyllonorycter viburnella. It is also consumed by the viburnum leaf beetle (Pyrrhalta viburni), an invasive species from Eurasia. The fruits are a food source for songbirds. Berries contain 41.3% fat.

The fruits appear blue. The major pigments are cyanidin 3-glucoside, cyanidin 3-sambubioside, and cyanidin 3-vicianoside, but the total mixture is very complex.

Native Americans used the young stems to make arrow shafts.

II. How to Grow and Care

Sunlight

Arrowwood viburnum in a cold environment loves to grow in full sun on slopes and edging rocks in its natural habitat. Varieties adaptable to warmer climates grow well in full sun to medium shade; long exposure to strong light should be avoided. They can be shaded by buildings or big trees. A certain amount of scattered light is needed in the flowering phase to ensure enhanced and continuous flowering in warmer climates, but overall, plants in this genus perform well receiving 5-6 hours of continuous sunlight in a day.

Temperature and Humidity

The shrubs prefer temperate conditions, though they have fairly good heat and cold tolerance within their growing zones. Arrowwood viburnum should be watered well in very hot weather to minimize plant stress, and these plants need protection if temperatures will be unseasonably cold to prevent foliage damage. Humidity typically isn’t an issue for these shrubs.

Watering

Moist soil makes arrowwood viburnum more vigorous. Insufficient water decreases the ornamental value of the whole plant and leads to abnormal flowering. Water management is the key to survival during transplanting. The newly transplanted plants must be irrigated continuously for 3-4 weeks to ensure that the soil is fully absorbent and closely connected with the root system.

During severe hot and dry conditions, 7 to 8 mm of water weekly is sufficient. In daily maintenance, just keep the soil moist. Too much soil moisture affects air permeability, inhibits root respiration, causes rotten roots, and even causes the plant to die in severe cases.

Soil

Arrowwood viburnum likes fertile, soft, slightly acidic soil with good drainage. It likes moist soil but does not grow well in waterlogged soils. It can grow in moderately fertile, fully drained soils that keep minimum moisture, but cannot withstand poor soil. The optimum soil pH range is 5.5-6.6. It can tolerate acidic media and drought with good air circulation in the root zone, which is made possible by the addition of peat moss or coco coir to the media. The best potting soil would be to mix 1 part of fully decomposed organic matter into 2 parts of garden soil.

Fertilizing

Applying organic fertilizer in a planned and reasonable way can improve soil structure, increase soil organic matter content, and increase soil fertility. Fertilization is indispensable for growth, and fertile soil promotes the overall growth of the plants. When transplanting, apply an adequate amount of basal fertilizer, and apply fertilizer every 2 weeks during the flourishing growth stage. Fertilizer should be applied when the weather is clear and the soil is dry.

To ensure normal growth, fertilization should be carried out before the dormant period or after the leaves are preparing to fall, and before the soil freezes. Don’t fertilize the soft cuttings until they start sprouting. For transplants, fertilizer rich in nitrogen is necessary to initiate vegetative growth. In the later flowering stages, it can be replaced with high phosphorus fertilizer.

Planting Instructions

The best time for transplanting is in late spring or early summer. It is best to plant them all on the same day. Take care that roots aren’t exposed to direct light and are buried deep into the planting pit.

Before planting, you need to know the height of a fully mature plant for the variety that you are growing. Generally, the role of thumb is to divide the height of the plant by 2 to determine space. For example, if the selected variety is predicted to grow 4 m tall at full maturity, space the plants 2 m apart. Dig a pit measuring 30 cm deep and 30 cm wide.

Pruning

Arrowwood viburnum shrubs don’t need extensive pruning. Right after the plant is done flowering, prune any stems necessary to maintain the shrub’s shape. Avoid taking off more than a third of the shrub’s overall size. Remove any dead, damaged, or diseased portions of the shrub whenever you spot them.

Propagation

Cuttings

Arrowwood viburnum can be propagated by softwood or hardwood cuttings. Softwood cuttings can be taken in the spring or early summer, while hardwood cuttings should be taken during the winter dormant season or early spring just before the plant begins actively growing again. Here’s how:

• For softwood cuttings, take a cutting of a vigorous branch between 4 and 6 inches in length using clean gardening shears. Remove leaves from the lower third. For hardwood cuttings, choose a strong stem and cut 8 to 10 inches of it with your shears, then strip the leaves from the bottom half and make sure to include at least a few leaf nodes.
• Fill 4-inch pots with a moist mixture of potting mix and make a small hole in the center of the mix.
• Dip the stem in rooting hormone. Plant the cutting in the pot.
• Cover the cutting with a plastic bag or dome and keep it in indirect light, with damp soil, until the roots begin to form (for softwood cuttings, this takes about four weeks). Rooting might be slower for a hardwood cutting, but should still occur within a few months.
• Test for rooting by pulling gently on the plant. If there’s resistance, the plant is beginning to establish roots. Remove the plastic and place the cutting in a spot that provides bright, indirect light.
• Before planting in the landscape, gradually acclimate your plant to the outdoors by placing it in a protected area for a few hours every day for a week to 10 days.

Seed

Growing viburnum from seed is possible, but it’s a lengthy and finicky process that most gardeners do not attempt. Because propagation from cuttings is fairly easy and has a good success rate, it is the propagation method of choice.

Pests and Diseases

• Common Pests & Plant Diseases

Arrowwood viburnum shrubs don’t have serious issues with most pests or diseases. However, they might be bothered by the viburnum leaf beetle (Pyrrhalta viburni). This beetle has become a major problem for viburnum shrubs in Europe and North America.1 Both the adult beetles and their larvae eat the leaves of the bushes. If not controlled, the pest can defoliate your shrubs completely, resulting in their death.

The female beetles lay their eggs on the undersides of the shrub stems. If you notice dark spots there, it’s best to prune off those stems and dispose of them before the eggs hatch in the spring. Use organic pesticides only for serious infestations, as they can also kill beneficial insects.

• Common Problems 

Like many native plants, arrowwood viburnum is a trouble-free plant when grown in its native range where it is well-adapted to the growing conditions.

Potting and Repotting 

Arrowwood viburnum is too large to work well as a container plant. For a potted plant, choose a dwarf variety such as witherod viburnum ‘Lil’ Ditty’, a cultivar of Viburnum cassinoides. Pot the plant in moist, well-drained soil with an acidic pH. If the plant visibly starts to outgrow its pot or roots begin growing from the top or bottom of the pot, repot it in a container one to two sizes larger.

Overwintering

Arrowwood viburnum is a winter-hardy shrub that can tolerate temperatures as low as minus 50 degrees Fahrenheit in its coldest growing region, USDA hardiness zone 2. These tough plants do not need winter protection.

III. Uses and Benefits 

There are shrubs which work better for tight formal hedges, but arrowwood viburnum distinguishes itself for loose hedges and screening because it is so vigorous, hardy, and reliable to grow. It also works well as a background for showier plants and flowers.