How Fast Does the American Mountain Ash Tree Grow? A Complete Guide

If you’re interested in planting an American mountain ash tree, its growth rate is likely an important factor in your decision. These lovely trees provide great aesthetic value to landscapes with their showy white flowers in spring and bright red berries in fall. But how fast do they reach mature size? Let’s take a close look at the growth rate and other key details about American mountain ash.

An Overview of American Mountain Ash

The American mountain ash (Sorbus americana) is also commonly known as the American mountain ash or roundwood It’s a small to medium-sized deciduous tree, growing 30-50 feet tall with an oval to rounded crown shape

Native to northeastern North America, mountain ash thrives in moist well-drained soils and full sun to partial shade. It can tolerate a wide range of soil pH levels.

This lovely tree provides multi-season interest with:

• Clusters of white flowers in spring
• Green, pinnately compound foliage in summer
• Bright orange-red berry clusters in fall
• Yellow, orange, red fall leaf color

The berries attract birds and other wildlife. Mountain ash wood is used for tool handles and craftwood. It’s also gaining popularity as an ornamental landscape tree.

Growth Rate of American Mountain Ash

So how fast does American mountain ash grow?

The average growth rate of mountain ash is about 1-3 feet per year when the tree is young and actively growing under optimal conditions. It has a medium to fast growth rate compared to other landscape trees.

Here’s a more detailed look at its growth pattern:

• Years 1-5: Young mountain ash trees can grow around 3 feet per year when they’re establishing. Proper planting, watering, sunlight, and care will encourage vigorous growth.

• Years 5-10: Growth starts to slow down a bit as the tree matures. You can expect 1-2 feet of growth per year during this stage.

• Years 10+: Once established, mountain ash grows around 1 foot per year or less. Growth continues at a slower pace as it nears maturity.

In favorable growing conditions, mountain ash can reach its full mature height of 30-50 feet in as little as 20 years. But it may take 25-30 years or longer to fully fill out.

Let’s compare the growth rate of mountain ash to other landscape trees:

• Faster growing: Hybrid poplar, silver maple, black locust, willow species
• Similar growth rate: Red maple, Washington hawthorn, flowering crabapple, amur maackia
• Slower growing: Most oaks, ginkgo, hickory, ironwood, eastern redbud

So while not the absolute fastest growing, mountain ash is on the quicker side for small to mid-size landscape trees. This makes it a great choice if you’re looking for a tree that fills in within a decade or two.

Factors Affecting Growth Rate

Several factors play a role in determining American mountain ash growth rate:

Climate and Location

Mountain ash grows best in cooler regions with moderate rainfall and humid summers. Some key climate factors include:

• USDA Hardiness Zones: Zones 3-7
• Sun exposure: Full sun to partial shade
• Precipitation: Prefers moderate rainfall of 30-60 inches per year
• Soil moisture: Consistently moist, but well-drained soil

Trees in the optimal climate and location will grow faster. In warmer southern regions, growth may be reduced.

Soil Conditions

Mountain ash thrives in loamy, moderately fertile soils with good drainage and organic matter. Ideal soil conditions include:

• Soil type: Loam, silt loam, sandy loam
• Drainage: Well-draining to avoid sitting in water
• pH: Adaptable to acidic to neutral pH of 5.0-7.0
• Fertility: Average nutrients; avoid very poor or very rich soil

Poor soils that are sandy, compacted, or nutrient deficient will lead to slower growth. Providing compost or fertilizer can help in less ideal soils.

Planting and Care

Giving mountain ash the right start when planting and proper care will ensure good growth:

• Plant in spring after the last frost
• Space at least 15-20 feet apart for air circulation
• Water 1-2 times per week for the first two years
• Apply 2-4 inches of mulch to retain soil moisture
• Prune only for structure and safety once established
• Watch for signs of disease and treat problems promptly

With proper planting and optimal early care, you’ll set your mountain ash up for vigorous youthful growth.

Genetics

Some mountain ash tree cultivars are bred for certain traits like columnar form, dwarf size, enhanced leaf or fruit color, or other features.

Cultivars developed for compact size likely have slower growth rates. Check tags or descriptions to see if a particular variety has been selected for slow growth.

Tips for Faster Growing American Mountain Ash Trees

If you want to maximize growth rate for your American mountain ash, here are some helpful tips:

• Select a sunny spot sheltered from strong winds
• Prepare the soil well by tilling and adding compost
• Give supplemental water during dry periods, especially for young trees
• Mulch around the tree to conserve soil moisture and reduce weeds
• Stake the tree for support the first 2-3 years as needed
• Prune only when necessary to encourage dense branching
• Apply a balanced, slow-release fertilizer annually in early spring
• Control pests like borers that may slow growth

With the right site, care, and environment American mountain ash will grow vigorously. Be prepared for it to fill in quickly compared to other landscape trees!

Mature Size and Lifespan

Once American mountain ash is fully grown, it reaches a mature size of 30-50 feet tall with a 25-35 foot spread. The crown is oval to rounded in shape.

These trees have a lifespan of around 100 years under urban growing conditions. Some mountain ash in ideal forested settings may live up to 150 years.

At maturity, mountain ash has gracefully ascending branches and a rounded form. It stays at a manageable size compared to many large shade trees. The max size makes it well-suited for planting near homes or under utility lines.

Adding American Mountain Ash to Your Landscape

If you’d like a relatively fast-growing ornamental tree, American mountain ash is an excellent choice. It brings multi-season beauty and attracts wildlife.

Thanks to its moderate mature size, mountain ash works well in many landscape settings:

• Accent or specimen tree
• Group plantings or mass plantings for erosion control
• Screening along fences or property lines
• Near patios, decks, or outdoor living areas
• Naturalized areas or woodland gardens
• Parks and other public spaces

With proper planting and care, you’ll enjoy watching your American mountain ash grow quickly into a lovely landscape specimen in just a few short years. It’s the perfect combination of beauty, wildlife value, and brisk growth rate.

Frequency of Entity Occurrences:

American mountain ash: 15
Mountain ash: 22
Growth rate: 16
Mature size: 2
Lifespan: 2
Landscape: 6