What is the fastest growing shrub in Zone 4?

When choosing shrubs for Zone 4 gardens, growth rate is an important consideration. Zone 4 covers a large area of the northern United States and southern Canada, with average minimum winter temperatures between -20°F and -30°F (-29°C and -34°C). Many gardeners in this cold climate want fast-growing shrubs to provide privacy or structure quickly. With proper selection and care, certain shrubs can grow over 3 feet per year in Zone 4.

The Fastest Growing Shrubs in Zone 4

Here are some of the fastest growing shrubs for Zone 4:

Forsythia

Forsythia is a classic spring-blooming shrub that thrives in cold climates. It can grow 3-4 feet per year once established. Rapid growth results in long, arching branches that bear masses of bright yellow flowers in early spring. Regular pruning encourages dense growth. Forsythia grows in most soil types and needs full sun for best flowering.

Rose of Sharon

Rose of Sharon (Hibiscus syriacus) is a fast-growing, multi-stemmed shrub reaching 8-12 feet tall and wide. It can grow up to 4 feet per year once settled in. This shrub features large, showy flowers in late summer. The flowers come in white, pink, purple and blue. Rose of Sharon thrives in full sun and well-drained soil. Prune regularly to promote bushy growth.

Spirea

Many spirea cultivars grow quickly in Zone 4. They produce clusters of white or pink flowers on new wood each spring. Some examples are Bridalwreath spirea (3-4 feet per year) and Anthony Waterer spirea (2-3 feet per year). Spireas prefer full sun to part shade and average to moist soil. Prune them back by one-third each spring to encourage new growth.

Mockorange

Mockorange (Philadelphus) includes many fast-growing species and cultivars perfect for Zone 4. Most grow 3-4 feet per year and produce fragrant white flowers in late spring. Mockorange thrives in average, well-drained soil and full sun. Prune after flowering to shape the shrub and remove dead wood.

Bush Honeysuckle

Not to be confused with invasive honeysuckles, bush honeysuckles like Diervilla and Lonicera are excellent non-invasive choices for cold climates. Fast-growing varieties like ‘Kodiak’ diervilla and ‘Red Tips’ bush honeysuckle grow around 3 feet per year. They produce yellow or red trumpet-shaped flowers throughout the summer followed by red berries. Plant them in full sun to part shade.

How to Maximize Growth

Follow these tips to ensure your Zone 4 shrubs reach their full growth potential each year:

• Select a site with full sun and fertile, well-drained soil.
• Prepare the planting area thoroughly by amending the soil with compost.
• Space shrubs according to their expected mature width to prevent overcrowding.
• Water new plantings regularly for the first two years until they establish deep roots.
• Apply 2-3 inches of mulch around shrubs to conserve soil moisture and regulate soil temperature.
• Fertilize shrubs with a balanced, slow-release formula each spring.
• Prune frequently to remove dead wood and encourage dense, compact growth.

Best Practices for Planting

Follow these simple practices when planting any new shrub to get it off to the healthiest start:

1. Dig a hole twice as wide but no deeper than the root ball.
2. Set the shrub in the hole so the top of the root ball is level with the ground. Remove any burlap or containers.
3. Backfill with the native soil, gently tamping down to remove air pockets.
4. Create a water basin by building up a ridge of soil around the outer edge.
5. Water thoroughly until the soil is saturated. Finish by placing 2-3 inches of mulch around the shrub.

Ongoing Maintenance

With proper care after planting, your fast-growing shrubs will thrive for years to come:

• Water once per week during the first two summers, more often in periods of drought.
• Apply fresh mulch each spring to conserve moisture and reduce weeds.
• Prune frequently in spring or early summer to shape and improve flowering and growth.
• Watch for pests like aphids and mites and treat promptly if found.
• Protect shrubs from winter damage by pruning late in the season and mounding soil or mulch around the base.

Ideal Growing Conditions

While the shrubs mentioned above grow quickly in a wide range of soil types and sunlight levels, they will reach maximum growth potential under these ideal conditions:

• Full sun – At least 6 hours of direct sun per day.
• Fertile, well-drained soil – Loam enriched with compost is ideal.
• Moderate water – 1-2 inches per week, adjusted based on rainfall.
• Shelter from winter winds helps protect from desiccation.
• Good air circulation to prevent disease.

Conclusion

When you need a privacy screen, windbreak, or focal point established quickly in your Zone 4 landscape, select fast-growing shrub varieties suited to cold climates. Give them a sunny spot with amenddd soil, consistent water and plenty of room to reach their mature size. With proper planting and aftercare, you can expect growth of 3 feet per year or more from top performers like forsythia, rose of Sharon, spirea and mockorange.