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Did you know, not all trees you find in a nursery will be acceptable to plant? Thus, it’s important to understand how to pick quality trees to plant. The following guide will teach you how.
Here’s a table outlining things to consider before selecting a tree from a nursery.
I manage the planting of thousands of trees a year. Before the planting season begins, I travel to my supplier and assess every tree in my order. Then, throughout the season I need to assess the quality of each tree as it gets delivered. The following is the guide I use to assess each tree.
Buy the best & you’ll only cry once
What to Look For When Purchasing a Tree From a Nursery
It’s important to be rigorous when assessing a tree’s quality. Poor stock will never grow to its full potential. You will save time and money by purchasing only the best stock.
Below are the selection criteria to use when selecting a tree. With each set of criteria, there will be a description to help you understand what you’re looking for.
True to Type
A tree that is true to type is a tree that matches what you ordered. There are several ways a tree may not be true to type. These ways include:
- Getting a completely different species than what you ordered
- Getting a different subspecies
- Different stock origin (stock grown in a different region)
Summary: Make sure the tree you receive is exactly what you ordered
Health and Vigour
A tree that is healthy and vigorous has a much better chance of survival. To assess the health and vigour of a tree, you will need a healthy tree for comparison. You can find a healthy specimen by speaking to someone at the nursery. Otherwise, a Google search can help.
To assess the health of a tree, here are some things to look for:
- Foliage size
- Foliage texture
- Foliage color
To assess the vigour of a tree, look at how the tree is growing. Do the branches extend out as much as those of a healthy specimen?
Summary: Make sure the tree you are buying looks strong and healthy
Free From Pests and Diseases
Any tree you buy should be free from any pests or diseases. Here’s why:
- Pests and/or diseases will stress a tree, making it harder to establish
- An infected tree can spread pests and diseases to its new home
To check for pests and diseases, check the tree’s foliage. The foliage is where you will notice the signs of an infestation.
You may find pest or disease damage on a tree. If so, measure how much of the foliage is affected. Anything less than 10% is acceptable. However, if over 10% of the tree’s foliage is affected, disregard the tree.
Summary: Make sure the tree you are buying is free from significant pest and/or disease signs and symptoms
Free From Injury
A tree that is injured will struggle to establish itself in its new home. Resources will be spent on healing, rather than establishing.
Check over each tree thoroughly. Look for signs of damage. Some signs of damage include:
- Tears in bark
- Snapped limbs
- Significant scratches or wounds
Summary: Ensure your tree doesn’t show signs of significant damage
Crown symmetry refers to how balanced the crown is. A tree should have an even-looking crown. Trees that have much more growth on one side of the crown will run into problems.
Here are the two main reasons why crown symmetry is important:
- Trees with symmetrical crowns will have a stronger structural integrity
- Trees with symmetrical crowns are aesthetically pleasing
A visual assessment can determine a tree crown’s symmetry. From the book, Purchasing Landscape Trees:
Assessment criterion: Difference in crown bulk on opposite sides of the stem axis must not exceed 20%
Summary: Make sure your tree’s crown is symmetrical
Uniformity of Growth
Growing in uniformity means the tree grows at a steady rate. Different parts of the tree aren’t growing faster than others.
The biggest cause of uniformity problems is fertilization rates. Nurseries will fertilize their stock to help them establish. Sometimes the nursery will apply too much fertilizer, or the rate of fertilization will vary too much.
The main problems of poor uniformity are:
- Poor looks
- Spacing problems
- Weaker stems
To measure a tree’s uniformity, measure the internode lengths.
The internode length is the distance between each stem on the tree. Measure the distance between each stem. Start at the first stem, and work your way up to the highest stem.
The internode lengths should all be similar. The longest internode should be within 20% of the shortest.
Summary: Ensure your tree is growing evenly and in uniform
Tree Is Self-Supporting
A tree should be able to support itself, without any artificial means. It’s not ideal to support a tree with stakes and ties. If done incorrectly, the tree will grow to rely on the stakes, never adapting to support itself.
Many nurseries will support trees with thin bamboo, stakes. Without these stakes, the tree would keel over.
Look for trees that don’t require any artificial support. However, if you do choose a tree that needs support, ensure you stake the tree the right way.
This guide will teach you how to plant a tree, including how to stake a tree properly.
Summary: Choose a tree that can stand up by itself
Sometimes a nursery will need to prune its stock. Best arboricultural practices need to be followed when pruning.
So, when inspecting stock, look for evidence of pruning. Poor pruning can lead to many problems, including:
- slower growth
- root damage/infection
- interfere with the tree’s aesthetics
Ross Clark details what to look for when assessing a tree’s pruning history. From his book, Purchasing Landscape Trees:
Assessment criteria: Fresh (i.e current) pruning wounds must be confined to less than 25% of the clean stem height. All pruning (current and existing) must be a clean cut at the branch collar. The diameter of the wounds (current and existing) must not exceed 50% of the stem diameter immediately above the point of pruning.
Summary: Poor pruning practices can affect the growth rate and overall health of a tree. Look for clean cuts at the branch collar. Avoid tree’s that have been hacked
Sound Branch Attachment
Branches that suffer from poor attachments can cause issues in the future. These branches are at a higher risk of failing.
Failed limbs can:
- Cause injury
- Cause damage to surrounding infrastructure/flora
- Open the tree up to infection/disease/pests
When inspecting stock, look for:
- U-shaped unions, rather than V-shaped unions
- Co-dominant stems free from included bark
Summary: Poor branch attachment can lead to limb dropping. Look for strong branch attachments
Proper Root Division
Tree roots are essential to the overall health and structure of a tree. Buying stock with a poor root structure will hinder the success of your tree.
With the proper root structure, your tree will be able to absorb an abundance of water and nutrients. Plus, these roots will support the rest of the tree later in life.
Roots must spread out from the base of the tree. Spreading out will increase the root system’s surface area, allowing for more water and nutrient absorption.
The process of spreading out is called root division.
The division must also be progressive. The progressive division allows for a much better structural base.
When selecting a tree, this is the type of root division you should be looking for: