Where to Put Down Roots: Choosing a Planting Site

You're ready to plant a tree this fall... but where should it go? Learn more about five important components -- climate, soil, structure, topography, and sunlight -- to keep in mind when determining planting location.

1. Climate

Climate factors include average temperature, rainfall, humidity, atmospheric pressure, wind, and amount of sunshine. Trees should be chosen according to the climatic conditions of a particular location. One tool for assessing the climate of a region is the USDA’s Plant Hardiness Zone Map. The hardiness map displays the average annual extreme minimum temperatures that a region may experience. Why does this matter? It’s important to choose a tree that will be able to tolerate those extreme minimum temperatures.

Another factor of climate to consider: average annual rainfall. While it’s important to water a tree yourself during its establishment period, we also recommend choosing a species that can tolerate the amount of rainfall your region receives. Rainfall can vary widely even in areas close to each other! Check out this precipitation map produced by the UT Institute of Agriculture in order to determine the average amount of rainfall within specific areas of Tennessee.

2. Soil conditions

After considering climate, soil type is another major determinant. Soils are primarily classified as clay, sand, or loam, but they can be a mixture of any two (or all three!) types.

The soil texture can be determined by feel, as outlined in this USDA sponsored flow chart. Another tool to assess the soil characteristics is with the USDA’s Web Soil Survey. This interactive map lets the user choose a particular location and then compiles state and county soil data in order to provide likely soil traits at that location.

Another useful tool is the pyramidal chart below. It might look a little intimidating, but can be very useful once you get used to it. Each side of the pyramid is a percentage of soil type, and when all three are added together, you can see how the soil would be described:

Image source:
https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_031477.pdf

3. Topography

Is the location flat or hilly? Understanding the topography is also vital for choosing the right kind of tree for your site. Planting on a steep slope, for example, will cause water to run off faster than on level ground, which prevents some of that water from being infiltrated into the soil. But this doesn’t mean you can’t plant on a slope! A helpful guide for creating a planting shelf can be found here on Southern Living’s website.

Image source: http://southernlivingplants.com/how-to/article/3-steps-to-planting-trees-on-a-slope

Also, if your planting location is in a flood zone or low-lying area, make sure to select a tree species that can tolerate a lot of water. Flood-prone areas can be found by using FEMA’s interactive flood map.

4. Nearby structures

Look around your planting site. Are there any structures that may interfere with the development of your tree? Buildings, sidewalks, or power lines may impede tree growth or provide reasons to prune or cut down the tree. You don’t want to end up with a tree looking like this:

Image source: https://laidbackgardener.blog/2018/02/15/how-to-avoid-power-line-pruning/

Also, trees that are too close to a sidewalk or other impervious surface might not have enough room for their roots. While every tree has different growth characteristics, it is generally accepted that trees growing up to 30 ft. in height should be placed 3-4 ft. away from pavement. Those that are 30-50 ft. should be placed 5-6 ft. away from pavement, and trees that grow taller than 50 ft. should be placed at least 8 ft. from pavement.

Trees that are planted too close to a building or under power lines may require severe pruning as they age. To avoid this, always determine how tall your tree species will likely be at maturity and what the spread of the canopy will be. When planting near structures, it is usually better to go with an understory tree. Classified as trees growing no more than 30 ft. in height, understory trees are well suited for planting in urban environments near buildings and other structures. The Metro Nashville Tree Advisory Committee has a list of recommended understory trees that can be found here.

But, there might be other structures besides those that you can see: underground utilities such as water, sewer, and gas lines. Serious damage or harm to yourself and others, as well as major fines, could result from utility lines being destroyed in the process of digging or by tree roots. It is therefore very important to call 811 or visit https://call811.com before digging. Call 811 is a nationwide service where dig requests are sent to utility providers in order to check for the presence of underground utilities in the specified location.

5. Sunlight

Different trees like different amounts of sunlight. Some prefer nearly full shade, while others must be in the sun for the whole day. Still others grow best with partial sunlight. Be sure to examine how much light your location receives on a typical day. Make note of the direction that the sun moves across the sky and if there are any structures that may block the light at particular times of the day. Note: trees requiring full sunlight means a minimum of six hours of direct sun per day.

Image source: https://www.thespruce.com/what-is-full-sun-partial-shade-1402372

With a little preparation and research, you can gather information about your planting site that will help you select the perfect, long-lived, beautiful tree. Stay tuned for another blog post soon about species selection.

Header image source: https://arbordayblog.org/treeplanting/need-know-planting-right-tree-right-place/

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