When properly planted and cared for, trees can provide benefits for generations. Considering site, species selection and placement will help to guide you as you begin your search for the right tree.
1. Know the planting site, including soil type and conditions, and choose species that will thrive in those growing conditions. Understanding soil pH and organic matter content are especially important.
2. Broad species diversity is strongly recommended across a community or neighborhood. A general rule of thumb involves the 10/20/30 rule, which suggests trying to achieve a limit of no more than 10% of any one species (red maple, hackberry, etc.); 20% of any one genera (oak, maple, pine, etc.); or 30% of any one family (beech, legume, elm, etc.). These are not hard rules but rather general targets. Some genera, such as oak likely deserve a greater allowance. On an individual site diversity should be balanced with the aesthetic benefits of repetition and massing. Planting all of one thing or one of everything is rarely if ever advised. For species selection information, click here.
3. Planting native species is good practice whenever it makes sense to do so. Native species help provide a sense of place and they typically do a better job of enhancing biodiversity having evolved to provide food and shelter for a wide variety of native birds, animals and insects. However, the appreciation of native species should not mean the exclusion of non-natives. The reality is that many introduced species and cultivars have proven to be very beneficial for our community forests, helping to make them more diverse, beautiful and resilient. Caution should be used, however, to avoid using any species that could become invasive in surrounding natural areas. A list of such species is available on-line at: http://snr.unl.edu/invasives/invasiveplants.htm.
4. Tree spacing recommendations can vary by species, purpose and design. However if we examine how trees grow naturally (within forests) we realize planting trees close together in mutually supportive groups increases survivability as the trees help protect each other from strong winds and storms. Scattering trees too far apart in the landscape is a larger problem than placing them too close together. NFS generally recommends that shade trees be planted about 20-40' apart, and evergreens and understory trees about 10-20' apart. However, there is nothing wrong in planting large-maturing trees as close as a few feet apart. Keep in mind that two or more trees planted tightly together will structurally rely upon each other as they grow and should be viewed as a single unit rather than as individuals. Do not plant within 25' from wires; 15' from buildings; and 3' from pavement.
Graphic: USFS Tree Owner's Manual
5. When possible, mass trees together with shrubs and other landscape plants in larger beds or islands to help create separation from conflicting maintenance zones, especially turfgrass. Such massing helps alleviate common problems such as over-irrigation, mower/trimmer damage, herbicide damage, and soil degradation.