Planting a tree is an act that has the potential to create long-term ecological and economic, as well as psychological, benefits. This potential may be magnified even more by planting native trees, which will fulfill their role as critical members of an ecosystem that has been dramatically urbanized. Before they can serve as keystones in their habitat, trees must go through the difficult journey towards maturity. Depending on the species this process may take decades. In our fast-paced world, a lot can happen around a tree before it reaches maturity. Our responsibility is to care for developing trees so that they may maximize their benefits to the ecosystem (which includes humanity) for generations.
Selecting the right tree for the right spot is critical to the future health and longevity of the tree, and it should be the first step you take before planting a tree. The “right spot” can include factors such as the soil type, amount of drainage, if there are other plants in the area, and if there are any structures or powerlines in the area. For example, planting a young tree next to powerlines might give you several years without any issues, but if that tree species reaches 100ft at maturity, you will have to take dramatic pruning action before the tree causes any problems. Dramatic pruning (topping) can compromise the tree’s natural form, as well as open it up to infection and disease. Some species are adaptable with regards to soil drainage, whereas some are more sensitive to changes. A species that prefers well-drained soils in higher areas may not perform well if you plant it in an area that holds water throughout the year. Pay attention to site details while making your selection.
Once you have selected your species and planting location, the tree needs to be planted properly. Most improper planting techniques concern hole depth, which are either too deep or too shallow. If the tree has a root ball, the hole depth should be slightly shallower than the size of the root ball, so that the trunk flare at the base of the tree sits 1-2 inches above the level of the surrounding soil (A good way to estimate depth quickly is to measure the root ball with your shovel handle and then dig until your mark is just is just higher than flush with the surrounding soil). This depth allows for proper root growth, decreasing the chances of girdling roots (planted too deep) or ground roots (planted too shallow) from forming. The hole should also be 2-3 times as wide as the diameter of the root ball, so that when the hole is backfilled with soil, there will be ample pore space generated for outward root growth. Like other plants, trees need to be watered in following planting to satisfy roots.
The addition of fertilizers may or may not be necessary as your young tree is developing. The only way to know for sure is to have a soil sample analyzed. This will give you a detailed report of what nutrients and minerals are in the soil, along with their concentrations, as well as the pH of the soil. If you are attempting to plant a tree that has very specific pH requirements, it might be best to perform a soil sample before you plant that particular tree. From the results of the soil sample, you can proceed with the appropriate fertilization protocol. Again, fertilization may not be necessary. You should monitor your tree from season to season to see if something appears to be wrong with it. The occurrence of problems in a tree that should be healthy often indicates issues in the soil. However, these issues may not always be related to nutrient deficiency. Soil compaction can also limit the roots’ ability to perform and can be caused by placing heavy objects too close to the tree or driving vehicles next to the tree. Even consistent walking can beat down paths and compact the soil underfoot. Compaction can be alleviated by soil aeration, but prevention of this issue is more effective.
If your tree is in the right spot and is growing without any problems, you may begin to consider light pruning. Pruning is not necessarily required and should only be done to assist in the health of the tree. Before you begin any pruning, ask yourself: Why am I making this cut? Why am I removing material from the tree? If your young tree has branches that are growing close together, and may one day start rubbing, you might consider removing the weaker branch so that both are not damaged by each other in the future. Some young trees may exhibit codominance, where there is more than one central leader. Codominant stems may grow large enough to form included bark, a situation where two stems have grown in circumference into each other and created a space between them that holds water. This is often a site of decay. These areas do not “fuse” into one larger stem, and they may eventually split due to the weakness caused by decay. Pruning out one of the codominant stems at an early age will allow the other stem to become the central leader. Anytime you prune, do not remove more than 20% of the tree’s canopy. If you and a professional arborist believe dramatic pruning may be necessary for a particular tree (maybe the once small Japanese Maple has outgrown its place right next to the front door), be prepared to slowly remove material over the course of a few years. Pruning all at once may indirectly damage the tree. If too many leaves are removed because of pruning, the tree may not be able to produce enough energy through photosynthesis to maintain a strong immune system, making it more susceptible to disease.
All in all, a lot of care goes into ensuring the health of young trees. In some cases, however, less is more. If you have taken care to pick the best species for the planting location, the tree can take care of itself (as every tree that occurs naturally has done throughout time). Our desire to have trees as part of a much larger landscape design in our homes increases the amount of care we must put into them. Attending to their needs from the early stages up through maturity allows them to not only serve as functioning members of the landscape, they can also provide you with a sense of peace, a realization of the vision you had in mind when you planted them. You will be repaid for the effort you pour into your young trees by the impact they have on your well-being, with the added benefit of knowing you have helped create a small pocket of nature within our concrete jungle.
By Bo Kelley, MBG arborist