6–8 minute read

Soil

Many plants, including natives, require specific soil conditions that may not match those in your garden. This is especially true for homes where the entire property was affected by construction, but remember that the soil adjacent to the foundation of any home can be alkaline due to buried concrete waste. Bulldozing during home construction often inverts soil layers and brings subsoil to the top. In addition, fill dirt has an unknown composition, so test your soil before selecting plants. For plants that will be smallish at maturity, such as perennials and small–medium shrubs, you can correct any deficiencies in soil fertility, pH or composition. For large shrubs and trees, the root system will become too large for amendment to be practical, so select plants based on their ability to survive under your current soil conditions. See Soil for detailed instructions for both situations.

Climate

Plant suitability is dependent on the extent to which our climate is compatible with a plant’s natural growth cycle. This includes far more than simple cold hardiness. Gardeners in the western US use a system devised by Sunset Magazine, available for our area in a more limited form, that considers latitude (daylength cycle), elevation (sunlight intensity, night temperatures, winter cold), the influence of large bodies of water (milder, moister winters) and topography (the Appalachians act as a barrier to shield us from Arctic air) as well as summer high temperatures and winter low temperatures to assess plant suitability. Unfortunately, most plants used in our area have not been characterized with respect to their sunset zone.

In general, plants from a similar climate such as the humid areas of Japan and Korea can be better suited to our area than natives from our own state that evolved in the very different climates of our coastal plain or mountains. Because our area experiences many weather extremes, including summer heat, drought, late spring freezes, damaging ice storms, and temperature lows unaccompanied by snow, a good approach is to visit older gardens to see what has survived. If an unfamiliar plant interests you, consider it an experiment and do a bit of homework before you purchase it. Learn about the native habitat and compare it to ours, also considering the microclimates that exist in your yard for sun/shade, air temperatures, wind, soil drainage, root competition, and ‘rain shadows’ (dry areas) cast by your house, tall hedges/fences or trees. These aspects of a plant’s native environment are especially important:

  • seasonal precipitation patterns
  • sunlight intensity and daylength cycle
  • humidity
  • seasonal temperature patterns (especially growing-season night temperatures), temperature consistency and extremes
  • periodic events like drought, ice storms, and frosts

Cold hardiness

The USDA definition of cold hardiness is the ability to tolerate a particular average annual minimum temperature. This definition is of limited value because it does not reflect factors that often are more relevant for plant survival such as the timing or duration of a low temperature or the occurrence/frequency of low temperature extremes. In addition, cold-hardiness describes only one of the three processes required for plants to survive cold weather: acclimation, maximum cold tolerance, and de-acclimation.

Provenance

Plant populations vary genetically across their natural range, with local conditions selecting for particular traits. Consequently, the climate in which a source plant originated (not the climate for the nursery where it is currently grown) can play an important role in determining plant performance. For instance, a dogwood that originated in New Jersey may be more cold tolerant but less heat tolerant than one grown in Florida. Similarly, hybrids selected as superior in one climate may not be suitable for a different one. Local sources of information and local growers are often the best approach.

Genetics

Species

Species are collections of individuals that are not genetically identical and thus can vary in habit, form, flower, fall color, etc.

Cultivars

Cultivars are individuals that have been selected from a species population because they possess a desirable trait(s), then propagated vegetatively to avoid genetic variation. Cultivars are often more expensive. However, sometimes the selected trait(s) are only expressed under certain conditions or are not different enough to warrant the extra cost.

Hybrids

Hybrids are crosses between species (or sometimes plants from different genuses). Hybrids can lose the distinctiveness of the parents, but often exhibit one or more of the following advantages: better visual appeal, greater vigor, longer flowering, improved disease or pest resistance or increased tolerance of various environmental conditions. Like cultivars, hybrids can be more expensive. Whether the added expense is warranted depends on your goals and the conditions present in your yard.