Trees are long term investments and bring beauty, shade and fresh air to us all. You may think that planting something means you stick it in the ground, cover it with soil and water it and hope for the best, but if you take small steps during the planting process, you can give your trees the best start. You will definitely reap the rewards at a later.
Finding the Trunk Flare
The roots of a tree need to be watered, but they also need access to oxygen, and planting a tree’s roots too deep can cause the roots to slowly suffocate. Planting a tree too deep can also lead to the development of circling roots which can girdle and choke the tree as it grows.
To ensure that the tree is planted at the right depth, you can use the trunk flare as a guide. Take a look at a tree that has grown naturally in the landscape, and notice the area where the base of the trunk gradually widens or flares out just as it enters the ground. This is generally called the trunk flare, or the root collar.
You need to plant your tree so that the base of the trunk flare is right at the surface of the soil or slightly above in dense soil.
So, it’s best to ignore the old advice of simply measuring the height of the root ball to see how deep to dig the hole. Rather go by the trunk flare.
You also may want to set the root ball on undisturbed soil to prevent the tree from sinking down into the hole as the soil compacts again, and covering the trunk flare.
Make the hole wide
This is done so that the soil around the hole can be easily penetrated by the roots. This is especially necessary with more dense soil such as clay where the sides can be slicked over with a hard layer, making it difficult for the roots to push through the soil.
Setting the tree in the hole
At this stage, you may want to loosen and spread the roots on the outside of the root ball before setting it into the hole, but it is important to keep the root ball intact. If you notice any roots that are growing around the root ball or that are kinked, trim them away.
Be very careful with the root system as you set the tree into the hole. Breaking the roots in the root ball can have serious, life-threatening consequences for the tree.
Use native soil to fill the hole
At this stage, you may think that adding fertilizer and organic material to the soil is a good idea, but the tree will do much better with the native soil that you dug out. If you fertilize the native soil, the roots will stay within this pocket of hospitable soil, and will not cross the boundary into the native soil and this will ultimately affect the overall health and longevity of the tree.
Stake only if absolutely necessary
Most gardeners think that a stake is imperative when planting a new tree. The natural movement of an unstaked tree helps it to develop a stronger trunk and a more robust root system, so staking a tree actually causes more problems than you may think.
You can spread mulch about 5 to 10 cm deep over the root zone to help keep moisture in the soil. Remember to make it into a doughnut shape and do not cover the trunk itself with mulch as this could cause rotting of the trunk amongst other problems.
Keep your young tree well watered during its first season in the ground – but take care not to over water. Just ensure that the water soaks through the entire depth of the root ball.