Spring will soon be upon us and, as the first tree blossoms come into bloom, we will have some glorious trees to admire and enjoy in parks, along roadsides and if you are lucky enough, in your local neighbourhood too! If you are thinking of planting any sort of tree in your garden, giving it the best chance to establish itself well and live a long and healthy life is critical, after all, trees are among the most expensive investments we can make in the garden.
It is really import to get the planting right so that you give the tree roots a strong start, and the planting depth of the tree in its new location is very important. Even many years after planting, mistakes in planting depth can come back to haunt the tree, and when a tree is planted too deep, or too shallow, it will often shorten the tree’s life expectancy.
So why is this? Well, trees have roots that grow horizontally, and, believe it or not, about 80 percent of the tree’s roots are in the top 18-24 inches of soil. Some trees have long tap roots that grow downwards and others have some deep anchoring roots, but most roots are in fact very close to the surface of the soil.
When a tree is planted too shallow, the roots that are supposed to grow horizontally have nowhere to go. They either stop at the edge of the planting hole or they grow into the mulch which does not hold moisture or nutrients well for the tree. One of the important functions of the roots closest to the surface is to take in air, use the carbon dioxide and make oxygen. When the tree is planted too deep, the roots still grow horizontally, not upwards and, as most of the roots stay too far below the surface, they do not get enough air to make enough oxygen.
When this happens, the tree declines earlier and sometimes more dramatically that it should. Growth may be slower or the tree may lose its leaves earlier in the autumn. Extreme weather such as a severe winter, or a summer drought can also have a more negative impact on the tree.
So, we can see why it is important to ensure that you plant it at the right depth, when it is first planted. This will give the tree the best chance to establish well and you the opportunity to enjoy it growing healthily in your garden for many years to come.
For some great planting advice, and ways to determine the correct depth, Matt Pottage at RHS Wisley shows how to plant a tree for best results in this excellent step-by-step video guide…