How Tall Can Boxwood Grow

If you’re planning a hedge or a foundation planting, you might be wondering how tall can boxwood grow. Understanding their maximum height potential is key to choosing the right variety and placing it correctly in your garden. These classic shrubs are beloved for their dense, evergreen foliage, but their final size can vary dramatically. This guide will walk you through everything that influences a boxwood’s height, from genetics to your care routine.

The simple answer is that boxwood height ranges from a petite 1 foot to over 20 feet tall. However, most common landscape varieties settle in the 3 to 6 foot range at maturity. The massive variation is almost entirely down to the specific cultivar you choose. A dwarf English boxwood will naturally stay small, while an older American boxwood specimen can eventually become a small tree. Knowing the genetic potential of your plant is the first and most important step.

The Biggest Factors That Control Boxwood Height

Four main elements determine how tall your boxwood will get. Think of them as the rules of the game for your shrub’s growth.

Variety or Cultivar: This is the number one factor. The plant’s DNA sets a hard ceiling on its possible size.
Age: Boxwoods are slow but steady growers. A 6-foot-tall shrub didn’t get there overnight; it’s likely decades old.
Growing Conditions: Soil quality, sunlight, water, and climate either help the shrub reach its genetic potential or stunt it.
Pruning: This is the tool you control. Regular shearing keeps a boxwood at any height you wish, below its natural maximum.

Popular Boxwood Varieties and Their Typical Heights

Let’s look at some common types. This list will help you match a plant to your space.

Dwarf and Small Cultivars (1-3 feet tall)

These are perfect for low borders, edging, or containers.

‘Green Gem’ (Hybrid): A rounded mound that stays about 2-3 feet tall and wide with little maintenance.
‘Green Velvet’ (Hybrid): Another hybrid, forming a soft sphere that typically reaches 3-4 feet, but is often maintained lower.
‘Justin Brouwers’ (Korean): A very compact, slow-growing globe that rarely exceeds 30 inches.

Medium-Sized Cultivars (3-6 feet tall)

This is the sweet spot for most hedges and garden structures.

Common Boxwood (Buxus sempervirens): The classic. Left unpruned, it can reach 15-20 feet, but it is almost always sheared into hedges 3-6 feet tall.
‘Green Mountain’ (Hybrid): Naturally grows in a conical shape, ideal for pyramids. It can reach 5 feet or more.
Japanese Boxwood (Buxus microphylla var. japonica): A tough, heat-tolerant type often used for hedges in the 4-6 foot range.

Large and Tree-Form Cultivars (6-20+ feet tall)

These are for specimens, tall screens, or if you have the patience for a large shrub.

American Boxwood (Buxus sempervirens ‘Arborescens’): This is the cultivar known for eventually growing into a large, tree-like form, up to 20 feet tall if untrimmed.
Common Boxwood (Buxus sempervirens) Unpruned: As mentioned, the standard species can, over many decades, achieve impressive heights.

How to Manage and Control Your Boxwood’s Height

You are not at the mercy of your boxwood’s genetics. With proper care and pruning, you can manage its size effectively for centuries.

Pruning: Your Primary Height Control Tool

Regular pruning is essential for maintaining shape and size. Here’s how to do it right:

Time it Right: The best time for major shaping is in late spring or early summer, after the first flush of new growth. You can do light tidy-ups in mid-summer, but avoid pruning in fall, as new growth may not harden off before winter.
Use the Right Tools: Keep hand shears for precise cuts and hedge trimmers for large, flat surfaces. Always make sure blades are sharp for clean cuts.
Thin, Don’t Just Shear: For health, occasionally reach inside and prune out whole branches back to a main stem. This opens up the center to light and air, preventing disease. Shearing only the outside creates a dense outer shell that can die back inside.
Never Cut Into Old Wood: Boxwoods can struggle to generate new growth from leafless, old wood. Always leave some green foliage on every branch you cut.

Optimizing Growing Conditions for Healthy Growth

To help your boxwood reach its intended, healthy size, provide it with:

Well-Drained Soil: Soggy roots are a death sentence. Amend heavy clay with compost.
Morning Sun & Afternoon Shade: Most boxwoods prefer protection from harsh afternoon sun, which can scorch leaves. Some newer hybrids tolerate full sun better.
Consistent Moisture: Water deeply during dry spells, especially for the first few years. A layer of mulch helps retain moisture and keep roots cool.
Balanced Fertilizer: In early spring, use a balanced, slow-release fertilizer or one formulated for shrubs. Avoid over-fertilizing, which can cause excessive, weak growth.

Common Problems That Can Stunt Growth

Sometimes, a boxwood isn’t growing because it’s under stress. Watch out for these issues:

Boxwood Blight: A serious fungal disease causing leaf spots, defoliation, and black streaks on stems. It can severely weaken or kill a plant.
Root Rot (Phytophthora): Caused by poor drainage, leading to yellowing leaves and stunted growth.
Winter Burn: Foliage turns bronze or brown from cold, dry winds. It can kill branches and limit growth.
Poor Planting Depth: Planting too deep is a common mistake. The root flare should be level with or slightly above the soil surface.

FAQ: Your Boxwood Height Questions Answered

How fast do boxwoods grow?

Boxwoods are slow growers. Most add only 3-6 inches of new growth per year under ideal conditions. This slow habit is what makes them so low-maintenance and easy to shape.

Can I keep a large boxwood variety small?

Yes, absolutely. Through consistent annual pruning, you can maintain a common boxwood as a 2-foot hedge for its entire life. You are ultimately in control of its dimensions in a managed landscape.

What is the tallest boxwood ever recorded?

While exact records are scarce, mature, unpruned American boxwood specimens in historic gardens and cemeteries in the southeastern U.S. are known to reach heights of 20-25 feet, with massive, thick trunks.

Why is my boxwood not growing taller?

Check for the common problems listed above. Likely culprits are poor soil drainage, insufficient light (too much deep shade), compacted roots, or pest/disease stress. A soil test can reveal nutrient deficiencies.

When do boxwoods reach their full height?

Given their slow growth rate, a boxwood may take 15 to 20 years to approach its mature genetic height. Many gardens contain boxwoods that are 50 to 100 years old, still looking great because of proper care.

Making the Right Choice for Your Garden

Selecting a boxwood is a long-term decision. Always choose a variety whose natural mature size is close to what you want. It’s much easier to maintain a 3-foot-tall ‘Green Velvet’ at 3 feet than to constantly fight a common boxwood trying to reach 15 feet. Read the plant tag carefully, and remember that the listed size is usually after 10 years, not its absolute maximum. Plan for the future, and your boxwood will be a beautiful, manageable asset for generations to come.