Selecting the Right Size Tree

Selecting the Right Size Tree


Betula nigra ‘Heritage’ at the nursery.

As one of the largest nurseries in the Greater Pittsburgh region, I think it’s reasonable to say we have one of the best selections of trees. With COVID-19 slowing down the pace of work and travel, I invite you to give your landscape a little more thought than usual.

Trees are always a good starting point to think about in spring as the weather warms up. Perhaps I can help. Trees are a vital part of the home landscape. They add height and structure to the home and garden. Properly placed trees help buffer the home from cold winds in winter and the heat in summer. They provide shelter and habitat for birds and other critical wildlife. Properly sited mature trees also have the potential to add property value. And, of course, they provide interest and beauty.

A section of our tree growing operation.

All these points apply to other private and commercial properties too.

When designing a landscape, I like to start with trees first since they usually mandate the most space. You can then work your way down to smaller plants from shrubs to grasses and perennials. This applies to large, medium, small, and little trees alike.

I break down tree sizes into four groups. Large, medium, small, and little based on the average mature sizes trees reach in the landscape. Keep in mind that trees are not finished growing at maturity and that these sizes are always estimates, so plan accordingly.

Little Trees (10′ high or less)

A grafted rose standard functions as a little tree.

I tried to think of a more sophisticated way of saying “extra small” or “miniature” and “little” is all I could come up with.

I consider little trees to be around 10 feet tall or less at maturity, with varying width. Cascading and weeping Japanese maples, a few conifers, and standards fit in this category. Standards are shrubs trained or grafted to look like miniature trees such as rose and hydrangea trees.

Picea pungens ‘The Blues.’

Little trees make the most impact in high visibility areas although be mindful to not plant them where they may block your window view or impede foot traffic.

One of my favorites is Malus sargentii ‘Tina’, the Sargent Tina Crabapple. This grafted tree, which is loaded with white flowers in spring and shiny red fruits in fall, looks great as a focal point or in the back of a perennial bed for height.

Some weeping trees fall into this category. Picea pungens ‘The Blues’, is a beautiful cultivar of blue spruce that only attains its height from being staked but otherwise just mounds and weeps. Larix decidua ‘Pendula’, or the European weeping larch, is similar in habit.

Small Trees (15-25′ high)

My parents’ 30-year-old Japanese maple, Acer palmatum.

I consider small trees to be trees that mature around 15-25 feet high and wide. These are a lot of your ornamental trees. I consider American dogwoods, flowering cherries, serviceberries, and upright Japanese maples to be in this category.

Pink flowering dogwood, Cornus florida ‘Rubra’. Photo by Aaron Grabiak.

These trees are better suited close to homes and under powerlines than medium or large trees. Small trees don’t structurally bother homes or damage walkways although they may need an occasional limb pruned. My parents have a 30-year-old Japanese maple that is as tall as house. Its roughly 8 feet from the house and 4 feet from the side yard walkway. It’s perfect where it is. It shades the house around midday and softens the look of the property. This would not be an appropriate place for a larger tree such as a weeping willow.

If you’re planting a small tree near the house, be sure it has the room to grow a full canopy. Planting too close to the house will not likely cause structural issues but it will look unflattering. If you purchase a tree that matures around 20 feet wide, I suggest planting it 10 feet away from the house.

One of my favorite trees in this category is Malus ‘Royal Raindrops.’ This flowering crabapple produces purple new growth and magenta blooms in mid-spring. It produces tiny, glossy maroon fruits in fall which are non-messy and a great food source for birds. Fall leaf color is great and the disease resistance, which plagues many older crabapple cultivars, is superb. I especially like crabapples because they are less troubled by exposed conditions than some small, flowering ornamentals.

Medium Trees (25-50′ high)

Himalayan birch, Betula utilis var. jacquemontii. Photo by Aaron Grabiak.

Fagus sylvatica ‘Purple Fountain’ at the nursery.

I consider medium trees to be over 25 feet tall but less than 50 feet at maturity. The width on most of these trees is usually around the same, or a little less.

Medium trees are good shade trees for smaller landscapes. I lump birch, black gum, red maple, and weeping beech in this category.

In our display gardens you can see a mature Fagus sylvatica ‘Pendula’ or green weeping beech and Fagus sylvatica ‘Purple Fountain, Purple Fountain beech. They are simply marvelous. There is a “wow factor” in seeing a mature weeping tree in the landscape.

Check out our display garden next time you visit!

Another big seller here at the nursery is Acer griseum, the Paperbark maple. This easy-going tree hosts brown-coppery exfoliating bark which provides year-round interest and beauty. It’s a slow grower so it requires patience but is a great landscape tree that fits the definition of a medium size tree.

Large Trees (50’+ high)

Dawn Redwoods, Metasequoia glyptostroboides, in fall. Photo by Aaron Grabiak.

Not much competes for awe with large, healthy trees in the landscape. They always stand out to me when I travel. When sited with proper distance from the house, they add property value and a myriad of psychological benefits. See here:

I consider tall trees to be over 50 feet tall or more at maturity. Depending on the tree, they might be just as wide as they are tall, or half as wide as they are tall. I lump Northern red oak, sycamore, and Tulip poplar in this category.

A mature White Oak, Quercus alba, at Gettysburg National Military Park. Photo by Aaron Grabiak.

Before planting, make sure large trees are planted at least half the mature width away from the house. If a tree matures at 50 feet wide, plant it at least 25 feet from the house, although more is better. If it’s a fast-growing tree, plant it even further as they tend to have weaker wood than slow growing trees. My weeping willow, Salix babylonica, is probably 60 feet tall with a spread around 2/3 of that. It’s sited reasonably far enough from the house but close enough that it casts shade in the afternoon which helps keep the house from heating as much as it would otherwise. Matter of fact, I didn’t use my air conditioning at all last summer.

Large shade trees also provide great space to gather under.

One of my favorite big trees is Acer x freemannii ‘Jeffersred, the Autumn Blaze maple for fast growth and fall color, native oaks for their longevity and their contribution to our ecosystems, and Pinus strobus, the Eastern White pine for its foliage.

Elliptical and Columnar Trees

An elliptical European hornbeam (Carpinus). Courtesy of Aaron Grabiak.

There are many cultivars of trees that are upright with an elliptical or vase-shaped habit and others that are columnar or fastigiate (very columnar). These trees attain much more height than their width. There are upright and fastigiate trees in each tree size category.

One evergreen staple we carry is Picea abies ‘Cupressina’, or Cupressina Norway spruce. This is an upright cultivar of Norway spruce that matures around 30 feet high and 6 feet wide. This provides a great vertical accent for narrower areas where a straight Norway spruce would be overwhelming.

One of our most popular upright trees is Carpinus betulus ‘Frans Fontaine’, an upright form of European hornbeam. This tree forms a dense canopy and matures around 35 feet high and 15 feet wide. I find these superior to Pyrus calleryana ‘Cleveland Select’, a popular city tree, in both aesthetics and durability.

I think the neatest columnar tree we have is Liquidambar styraciflua ‘Slender Silhouette’, the Slender Silhouette sweetgum. This fastigiate tree hosts star shaped leaves, amazing fall color, and produces very few fruits compared to the straight species sweetgum. Slender Silhouette matures around 50 feet tall with a width of only 4 feet. An impressive sight!

Right Plant, Right Spot

A clump form Serviceberry (Amelanchier spp.). Photo by Aaron Grabiak.

Hearkening last month’s blog entry, a healthy tree begins with its cultural requirements being met from the planning stages. Pay attention to the amount of sun your landscape gets. Think about the amount of moisture that’s present in the soil. Does the yard flood and quickly drain, is it always soggy, is it usually well-drained, or does it dry out often? How far does the soil go down before you hit impenetrable clay or shale? A healthy tree begins with its sunlight, soil, and water needs being met from the start.

Here are two examples. My weeping willow and river birch thrive in my backyard because it’s perpetually wet. If I planted a crabapple or Japanese maple, they would quickly die of root rot.

A commercial account downtown recently requested two weeping Japanese maples for a shady area. The clients were told it would be a great spot for green Japanese maples as red ones would lose their vibrant color. The clients chose a red-foliaged cultivar anyway and the result was two mottled burgundy-green trees that blended in with brick background. While they are still heathy, green would have looked better.

Matching trees to your landscape’s cultural conditions is the first step. Figuring out the right size of tree and where to plant it is the second step. You can then make your choice based on aesthetics after these are cleared. We know choosing a tree is a big deal, so we’d love to help next time you’re in. See you this spring!


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