Why Your Arrowwood Viburnum is Growing Sideways and What To Do

If you’ve noticed your arrowwood viburnum shrubs sending out long, sideways branches instead of growing upright, you’re not alone. This leggy, sprawling growth habit is common with arrowwood viburnums left unpruned. While normal, sideways growth is generally considered unattractive and can compromise the health of your viburnums over time.

In this article, we’ll explore why arrowwood viburnum grows horizontally and how proper pruning technique can train these shrubs to grow upright for a tidier, healthier landscape specimen.

Why Arrowwood Viburnum Grows Sideways

Arrowwood viburnum (Viburnum dentatum) is a naturally large, multi-stemmed shrub reaching 8 to 15 feet tall and wide under ideal conditions However, the species also exhibits a tendency for long, flexible branches to bend downward and outward from the weight of leaves, flowers, and fruit.

Here are some key reasons arrowwood viburnum grows sideways:

• Genetics – Arrowwood viburnum naturally forms an open, sprawling shape with arching outer branches. Without pruning, the shrub defaults to growing outward.

• Poor Branch Attachment – Weak, narrow crotch angles where branches join the main stem allow branches to sag and extend sideways.

• Shade Conditions – Insufficient sunlight causes arrowwood viburnum to stretch outward seeking light, resulting in loose, leggy growth.

• Overcrowding – Congested interior branches force outer branches to bend sideways looking for space.

• Lack of Pruning – Skipping seasonal pruning allows branches to extend horizontally without check.

While arrowwood viburnum’s sprawling habit creates admirable native shrub borders, leggy sideways growth is less desirable in manicured foundation plantings

Sideways Growth Causes Problems

If left to grow unchecked, arrowwood viburnum’s horizontal branching pattern can cause several issues:

• Irregular Shape – The shrub loses its rounded form and appears overgrown.

• Reduced Flowering – Long branches produce fewer flower buds.

• Weak Limbs – Extended branches become vulnerable to breaking or bending in storms.

• Lack of Air Circulation – Congested growth inside the shrub is susceptible to diseases.

• Unattractive Appearance – Sprawling, sideways growth looks unkempt rather than intentional.

• Invasive Growth – Branches can extend into pathways, other plants, orstructures.

• Short Life Span – Unpruned shrubs decline and die out faster.

Fortunately, there are effective pruning techniques to discourage sideways growth and keep arrowwood viburnum looking tidy.

How to Train Upright Growth Habit

With consistent pruning every year or two, arrowwood viburnum can be trained to grow in a rounded, upright form. Here are some tips:

• Prune Annually – Frequent light pruning is better than harsh pruning every few years. Remove undesirable branches while young and flexible.

• Choose a Central Leader – Select one main upright stem around which to shape the shrub. Remove competing vertical stems.

• Remove Lower Branches – Take off the lowest branches while young to lift the canopy and show off form.

• Cut Long Branches Back – Prune leggy horizontal branches back to just above a bud facing the shrub’s interior.

• Thin the Interior – Improve air circulation inside the shrub by judiciously removing some congested stems.

• Maintain Good Shape – Step back periodically while pruning and check form. Remove or shorten branches extending beyond the desired outline.

• Fertilize After Pruning – Apply a balanced fertilizer to encourage vigorous new upright growth.

With a commitment to consistent pruning technique, arrowwood viburnum’s tendency to grow horizontally can be overcome. Be patient, as it may take a couple seasons of pruning to re-train mature, overgrown shrubs. But the beautiful, blooming, bird-friendly shrub you end up with will be worth the effort.

When to Prune for Upright Growth

For best results in training arrowwood viburnum to grow upright, time pruning to the following seasons:

Spring

Prune in early spring before bud break. Removing old branches before new growth begins avoids cutting off developing flower buds. Cuts also heal quickly before growth starts.

Summer

After spring flowering, prune to shape and contains growth. Remove long shoots and trim branches extending beyond the desired outline. Avoid shearing hedges, which stimulates dense sideways growth.

Fall

Where winters are mild, a light pruning in early fall allows time for new buds to set before winter dormancy. Cut back long shoots and shape.

Avoid Mid to Late Winter

Pruning when arrowwood viburnum is fully dormant can stimulate growth before frost risk is past. Wait to prune until just before spring growth begins.

With a thoughtful pruning regimen timed to the seasons, anyone can overcome arrowwood viburnum’s natural sprawling tendencies. Be patient, prune regularly, and you’ll be rewarded with a shapely, flowering, fruiting specimen.

Problems That Contribute to Sideways Growth

Sometimes underlying issues like pests, disease, or growing conditions cause or exacerbate arrowwood viburnum’s sideways growth habit. Addressing these problems at the source helps minimize sprawling.

Insufficient Sunlight

Arrowwood viburnum thrives in full sun. Too much shade triggers leggy reach for sunlight. If possible, prune overhanging branches or trees to improve light levels.

Root Competition

Congested, shallow tree roots compete for nutrients and water. Space arrowwood viburnum shrubs well away from large trees.

Poor Soil Conditions

Compacted or infertile soil stunts growth. Test soil and amend with compost to improve drainage and nutrition.

Pests like Aphids

Sucking insects weaken plants and distort growth. Apply horticultural oil or insecticidal soap sprays to control infestations.

Diseases like Powdery Mildew

Fungal diseases impair growth and vigor. Improve air circulation and use fungicides to treat diseased plants.

When you optimize growing conditions and control problems, arrowwood viburnum gains the vigor to grow upright rather than sprawling.

Enjoy a Healthy, Upright Arrowwood Viburnum

With knowledge of arrowwood viburnum’s natural spreading tendencies, you can take steps to produce healthy, upright shrubs. Here are a few final tips:

• Select compact arrowwood cultivars like ‘Blue Muffin’ or ‘Compactum’ with better branch angles

• Give arrowwood viburnum the conditions it needs including full sun, well-draining soil, and ample room to reach mature size

• Commit to frequent, thoughtful pruning to remove unwanted branches and shape desired growth

• Be consistent! It takes diligent pruning over multiple seasons to re-train overgrown shrubs

• Tolerate some horizontal branching, which gives arrowwood viburnum its beautiful, natural form

The effort pays off in vibrant, flowering, fruiting arrowwood viburnum shrubs that provide years of seasonal interest and wildlife habitat. Don’t let undesirable sideways growth discourage you. With proper care, you can guide arrowwood viburnum’s growth habit in the upright direction you desire.