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Choosing the right tree for the right location is important. If you can select the right tree, it will grow and thrive with minimal intervention. Also, the right tree won’t cause issues to its surroundings.
With the right selection criteria, you can filter out inappropriate species.
In this article, I will teach you how to choose the right tree to plant. With this knowledge, you will be able to choose the right tree no matter where you are in the world.
What to Consider When Choosing a Species of Tree to Plant
When choosing a species of tree to plant, you must undertake an extensive selection process. This process will filter out many inappropriate tree species. You will be left with a few species that will survive and prosper in their new environment.
The following selection criteria are from the book Applied Tree Biology. This book is written by Andrew D. Hirons and Peter A. Thomas.
Here’s an overview of the selection criteria:
- Local Microclimate
- Ornamental Traits
- Mature Size
Regardless of the species, you select, you need to purchase quality stock. Learn how to select the right stock by checking out this article: What to Look for When Buying a Tree
It’s important the tree you select will do well at the location you intend to plant it. To assess the tree’s site suitability, you must understand your site. Some questions to consider are:
- What is the average yearly rainfall of this site?
- What are the average temperatures (winter and summer) of this site?
- What is the soil profile at this site (more on this in the next point)?
- Will the tree be exposed to strong winds or other tough conditions?
- What are the humidity levels like at this site?
- Is this site prone to drought or flooding?
- Does this site receive a lot of sunlight? Or is it a fully shaded area?
- What potential pests and diseases could infest this site?
- Could this site prevent different weed species?
- Will tree roots be an issue on this site?
Once you understand the site, you will be able to assess the site conditions against different tree species. So, you must do some research into each species you are considering.
For example, a shade-loving tree will not do well on a site that gets the full brunt of the sun all day. Likewise, a tree that does well in drought conditions will not do well in sites that are prone to waterlogging.
When selecting a suitable tree for your site, native trees to your area will do well. However, you aren’t limited to only native trees.
You can look select from trees all over the world. Just make sure their natural climate is comparable to yours.
The National Gardening Association provide a great tool to help identify your hardiness zone. Simply, put in your zip code and the tool will tell you what hardiness zone you are in. The tool will also give some general information about your zone. You can find the tool here: USDA Hardiness Zone Finder
The biological make-up of soil is important. Consider the following from the International Society of Arboriculture’s Arborist Certification Study Guide:
The relationship between tree root systems and the characteristics of the soils in which they grow has a greater influence on tree health than any other single factor.
Many tree disorders originate in soil deficiencies or disturbances, and trees are prone to many soil-borne pathogens. Where soil conditions prohibit water uptake by the roots, transpiration will be limited and the tree’s ability to photosynthesize may be compromised.
These two quotes make it clear how important soil is to the overall health of a tree. So, what kind of things are we looking for in our soil?
- Soil Profile
- Soil Texture
- Soil Compaction
- PH Levels
- Soil Nutrient Profile
After some thorough investigation, you can understand the make-up of your soil. From here, you can compare different trees and their tolerance to your soil conditions.
Now, you should have an understanding of the following:
- The proposed planting site
- The biological profile of the site’s soil
From here, you can ask yourself if it’s practical to plant a particular tree. As mentioned, different trees will have different tolerances to conditions. So, here are some questions you can now ask:
- Will I need to change the site to make a particular species work here?
- Will I need to change the soil profile to make a particular species work here?
Some trees might require a lot of work to help them thrive. All this work could cost a lot of time and money. So, ask yourself is it worth it? Perhaps you could find a similar species that tolerates your conditions.
The local microclimate refers to the climate of a small area compared to its surrounding areas. Let’s explore this concept by thinking of a city.
On any given day, different parts of a city can be experiencing different conditions. One area could be rainy, while a different area is windy and dry.
We can apply this concept when selecting a tree to plant. How does the climate of your site differ to the conditions of your surrounding area?
Here are some examples to get you thinking:
- Your neighbourhood is covered in trees. So, in summer, your neighbourhood doesn’t get too hot. However, the site you want to plant your tree has no surrounding trees at all. This site is much hotter and experiences the full brunt of the sun.
- You live in a neighbourhood with tall buildings. The surrounding area has moderate winds. However, the tall buildings surrounding your site create a wind tunnel. This wind tunnel forces the intense wind to blow through your neighbourhood.
Though you live in the right climate for a tree, the microclimate may not be right.
Phenology is defined as the study of the timing of recurring biological events, the causes of their timing with regard to biotic and abiotic forces, and the interrelation among phases of the same or different species (Leith 1974)
Here are some examples of recurring biological events in trees:
- Leaf Drop in Autumn
- Leaves Growing Back in Spring
- Flowers and Fruit Developing
In a tree’s natural habitat, these processes coincide with climatic events. For example:
- Temperature Changes
- Lighting or Day Length Changes
If you understand the phenology of a tree and your local climate, you can assess a tree’s suitability. The timing of all these processes is important. So, you want to make sure your local climate isn’t going to disrupt these processes too much.
A deciduous tree might be sensitive to temperature changes. Once it starts to get warm, the tree will grow new leaves. The tree can now take advantage of the sun and begin photosynthesising.
But, what if you plant this same tree in a colder climate? The tree won’t grow new leaves as early. Therefore, the tree won’t be able to photosynthesise for as long. The tree might not grow to its full potential, and it might struggle to heal injuries too.
Now, you understand so much about your local climate. You’ve also researched potential tree species to plant. You understand how these trees grow, and what conditions they prefer.
You can start to rate the tolerance of different species to your planting site. Here, you can filter out many trees that won’t tolerate your site.
You will be left with a list of species that will tolerate your site with minimal intervention. Now, you can start to choose species based on their looks.
If you’ve made it this far, you should have a list of species that will do well on your selected site. Now, you can start to assess each tree for aesthetic features.
Per Wikipedia, the definition of a biological ornament is:
A biological ornament is a characteristic of an animal that appears to serve as a decorative function rather than a utilitarian function.
So, when applied to trees, an ornamental trait is something that makes the tree look aesthetically pleasing. In other words, traits that make a tree look pretty.
Some ornamental traits to consider are:
- Autumn color
- Bark texture and color
- Leaf shape and color
- The overall form of the tree
- Fruit shape and color
The form of a tree refers to its overall shape. The form takes into consideration the tree as a whole. This includes:
- Crown size and shape
- Trunk size and type (i.e. single or multi-stemmed trunk)
- Canopy density
A tree with a large, thick canopy can shade your whole garden. Too much shade could make it difficult to grow grass or other plants.
A tree with a wide crown could pose a problem for smaller properties. The crown could easily grow towards your house or onto the road. But, on a large property, a wide canopy may not be a problem.
Formative pruning of a tree, when it’s young, can influence the overall form of the tree. Regular pruning will help the tree stick to the desired form. However, pruning is always the answer.
Every time you prune a tree, you expose the tree to stress and disease. If you are constantly needing to prune a tree, maybe it’s the wrong tree for your location.
Mature size is the size of a tree when it is fully grown. It may take some time, but eventually, the tree you plant will reach its full potential. Just because a tree grows well in your location, doesn’t mean you should plant it.
The average height of a Coastal Redwood is between 200 – 240ft. Not exactly a tree I’d want in the front yard of a suburban home. Though, something similar has been done before.
Are you planting the tree under power? If so, it will be better to plant a smaller tree that won’t grow up into the powerlines. This will cause all sorts of issues in the future.
Have you got an area of your home you want shading? If so, a small tree might not be the right fit for you.
A tree can be a great provider of shelter. Trees can provide shelter for the following:
- Birds and Animals
- Other plants
Some trees may attract certain types of animals. This can be good or bad, depending on your goals.
Shade is one of the biggest benefits trees provide. A tree shade can lower the temperature around your house, saving you money on electricity. So, when assessing a tree’s suitability for planting, consider shade potential.
The need for shade will be site-specific. An open space with no other shade will require a tree with a large spreading canopy.
But, if there’s plenty of shade already, you might look for a narrow, upright tree.
Once you’re ready to plant your tree, check out this guide: How to Plant a Tree: What You Need to Know to Get It Right. This guide is a culmination of my years of tree planting.
If you’re ready to plant a tree, you’ll need the right tools. The following article will help: All the Tools and Equipment You Need to Plant a Tree