Evaluating Existing Vegetation: How to Decide What to Keep?

There are many factors to consider when evaluating existing plants on your site.

The first step will be to understand what planting exists on the site, and what the potential impacts will be from site disturbance. A site inventory is recommended to identify existing species, as well as to demarcate any wetlands or critical ecological features that may be present on your site. Identifying the species present on your site is also important for another reason; it can provide clues about the characteristics of the soil on site, and what other species might be well-suited for any proposed improvements. A soil test is recommended to confirm this, but the existing vegetation is often a strong indicator of existing subsurface conditions. It may be worth enlisting the help of an expert if you are unsure about the identities of common trees and shrubs found in your area. Depending on your state’s environmental regulations and any applicable setbacks in your local zoning code, there may be limits to the amount of disturbance or modification that can be done on a particular part of the site.

One key area where this comes into play is with trees or shrubs planted along a street or public right-of-way. Street trees are often planted in an easement between the public sidewalk and the road, and there may be rules in place governing what modifications you are allowed to make in this area. Similarly, parts of a site immediately adjoining a corner or traffic intersection may require a setback to leave open a sight triangle for motor vehicle safety.

Depending on what you find, and how important this issue may be for you, it may be worth considering the ecological value of your existing plantings. Are they natives? Naturalized? Invasive? Broadly speaking, plants native to your region will contribute more to the local ecosystem, since birds and other animals are adapted to recognize these plants as a source of food, shelter, etc. Plants known to be aggressively invasive can crowd out the others, and may be better off removed from your site to ease the burden of maintenance later on. It is worth noting that, in some cases, invasive or non-native plants which are removed may not be able to be replaced in-kind – a notable example of this is Winged Euonymus (Euonymus alatus, also knows as “Burning Bush”). This plant exhibits strong ornamental characteristics and is desirable for its intense fall color, although it is listed as invasive and is therefore no longer commercially available.

If you are far enough along in developing your design to have established a clear goal or program – does the existing planting on your site conflict or interfere with your desired or proposed use? For instance, is there an existing shrub bed located where you’d like to have an open, level area for children’s play or a patio? It is worth noting here that replacing established plants with nursery stock will likely mean installing new plants at a smaller size, as larger sizes from a nursery will likely carry a cost premium.

When dealing specifically with trees on your site, it may be worth consulting a certified arborist to determine their health and whether any branches may pose a hazard to your property. Trees in poor health, at a risk of breakage, or with large limbs in proximity to a house or other site structures should be considered for removal, per the recommendation of an arborist.

In some instances, it may be possible to transplant a specimen from one location to another. Many species of trees and shrubs can be readily transplanted, although transplanting a larger-size specimen can be much more challenging from a logistics standpoint. Typically, younger and smaller trees experience less transplant shock because they lose less of their existing root structure when being dug up and moved, whereas larger trees may either die back or need time to adapt to their new conditions. If the only issue with a tree or shrub on your property is that it is in the wrong location, it may be worth inquiring about whether it is feasible to transplant it.

Finally, the ornamental characteristics of the trees or shrubs in question should be considered. Does the plant appear to be lush and healthy? Is its form intact? (sometimes branches can fall from above and crush a shrub, or heavy snowfall will cause breakage or deformation). Does the plant appear to have been the victim of pests? Or, does a particular tree or shrub carry some form of sentimental value? (i.e. “Grandpa planted that Spruce tree”).

These factors can help inform your decision making around keeping or removing existing plants. Determining what planting exists on your site and evaluating its viability in tandem with your design is a critical step toward the transformation of your landscape, or perhaps simply its preservation and management for years to come.