By Sharleen Pratt, Master Gardener
Peter Wohlleben in his well-know book, The Hidden Life of Trees, describes how trees are like families, continually communicating and supporting one another. Trees improve soil and water conservation, moderate climate, increase the wildlife habitat, reduce stress and improve health.
It is imperative we continue to increase the tree canopy in our ever-growing cities. This became more important after the recent storm that whipped through Southern Ontario and took out so many beautiful trees.
There are many factors to consider when planting a tree and it is easy to make mistakes. I learned this the hard way this past month when I was able to literally pull a 9-year-old tree out of the ground. Believe me, I am no incredible hulk! I made many mistakes when planting that tree; the picture shows it was planted too deep, the roots girdled around the original root ball and by amending the dug hole with compost the tree likely resisted growing roots into the surrounding clay soil.
Do your research and purchase a tree that is suitable for your yard conditions:
- How much sun and shade you receive each day?
- What type of soil do you have?
- Would you prefer a large tree or one that is smaller and more suitable to an urban setting?
- What growing zone do you live in? (Check out this Zone Map if you are unsure)
- Are you looking for a tree that will attract pollinators?
I would suggest you consider planting a native tree. Trees that occur naturally in our surrounding area are better adapted to local climate and soil conditions and more resistant to disease. Oak trees are a powerhouse for feeding birds and attracting pollinators and insects, however, they are quite large. A smaller tree to consider would be an Eastern Redbud or a Fall Witch Hazel.
Here is an article from Landscape Ontario with suggested native trees to consider.
In well-drained soils, the planting hole width should be two to three times the diameter of the root ball and only as deep as the root ball. Widening the planting hole produces a hole with a greater volume of loose cultivated soil that allows rapid root growth. This way roots gain access to a greater volume of loosened soil. Do not plant the tree’s root flare below the ground. The root flare should be within the top 5 cm of the soil surface. Use a brush to find the top of the root flare which is where the structural roots begin.
Remove any grass roots, weeds, rocks or other debris from the planting hole. It used to be believed that you should fill the hole with an organic amendment such as compost, however, recent research has found that this doesn’t improve root development or tree growth and can sometimes be detrimental to tree performance and survival. It is best to backfill in layers and lightly tamp and water to eliminate air pockets. Additions of mulch and compost can be surface applied in future years to supplied much needed nutrients.
CREATING A BERM
It is wise to build a 10 cm high berm of soil extending 15 to 20 cm around the periphery of the root ball. It should be firmed and is intended to keep water from flowing away.
Apply mulch such as leaf litter or untreated wood chips evenly at the base of the tree. It will help to reduce evaporation and suppress weeds. Be sure to pull the mulch about 15 cm away from the base of the trunk. The depth should be between 5 to 10 cm. I often see trees planted with mulch piled like a volcano. This does not allow the water to penetrate to the roots and can also cause damage and disease to the trunk of the tree.
Only stake the tree if the roots will not support its height or if it is exposed to high winds. If a tree must be staked, place stakes no higher than 1/3 the height of the tree. Stake the tree loosely so it can move naturally in the wind. This movement will help to increase the tree’s stability. The staking material should not constrict or rub against the bark of your plant. Remove stakes after roots have established, no longer than one growing season.
Remove all plant identification tags and any trunk protection or packaging material.
Supplemental watering is recommended the first 2-years after planting your tree. A sprinkle with the hose for a couple of minutes does more damage than good as this does not provide enough water to penetrate deep into the soil. Newly planted trees must be watered regularly until frost. Also, if water is pooling around the tree, cut back on the watering.
Do not be tempted to add additional fertilizer at this point. Mineral imbalances can occur and cause more vegetative growth than root growth.
Do not prune the tree beyond removing any dead, diseased or damaged branches.
For further information, check out this Tree Planting Guide from Landscape Ontario.