You are tired of that sparse bare spot under your tree and are ready to transform it into a lush green garden or aesthetically pleasing flowerbed. However, planting under mature trees can be a little tricky and you don’t want your new landscape addition to result in the loss of a century old tree. Planting beneath mature trees requires caution and careful planning to avoid damaging the tree roots. The goal should be to generate a healthy landscape where both the tree and the new plants can thrive simultaneously.
Protect Your Tree
The first step is protecting your tree. You will want to research your tree species and determine its specific needs. All trees have different environmental conditions that need to be met, for the tree to remain healthy. It would be beneficial to not only be aware of these requirements but, also ensure that these are already being met. You may want to call your local arborist and have them help you identify your tree’s specific needs and any deficiencies that may currently be present. As a general rule of thumb before planting under a tree, start with a healthy tree.
Selecting Plants for Under your Tree
Once you know your tree’s health requirements, you can start considering what you want to plant beneath the tree. You will want to take everything you’ve learned about your tree’s needs into consideration when selecting plants, as they will need to coexist in similar conditions. In addition, you should examine your tree’s canopy to determine what shading and rainfall requirements your plants will need. Extremely dense canopies will not only block out sunlight but, deflect rain. Therefore, if your tree has a large dense canopy, you may need to consider plants that are very shade tolerant and fairly drought resistant.
Avoiding Tree Root Damage during Planting
Some trees are more tolerant of root disturbance than others, you will want to determine how tolerant yours is. However regardless of tolerance levels, it is always important to minimize root disturbance and root damage when planting under a tree.
It is not uncommon for people to believe that most tree roots are deep in the soil, creating sort of a mirror image of the tree’s crown. However, most tree roots are relatively close to the surface and spread out even beyond the drip line. Keeping this in mind, you will want to plant smaller container plants, regardless if they will grow to be much larger in the future. Smaller plants mean smaller planting holes and less disturbance to the tree root zone. In addition, in the mindset of not disrupting the tree roots unnecessarily you should plant perennials, rather than annuals that will need to be replanted every year. This way you will only need to plant once and the root systems can become well established and find a nice healthy coexisting balance.
Resist the Urge to Raise the Grade or Over Mulch
You may feel like you want to add soil around your tree, especially if there are a good number of large shallow roots. However, adding more than a few inches of soil can result in a reduction of water and oxygen reaching the tree roots; which will cause the tree to slowly decline. It is best to simply plan your planting layout around these larger roots. To avoid rot at the base of the tree trunk DO NOT pile soil or mulch up on the tree trunk. You can safely place approximately 1-2 inches of mulch around the new plants, leaving space between the mulch and tree trunk. Be careful not to put down too much mulch, as it will trap moisture and could cause tree rot.