Taking the time at this stage to evaluate the growing conditions of your site location will maximize the likelihood that the plants you install will survive and hopefully thrive in your garden. Four of the most important of the factors which should be considered are discussed below.
1. Sunlight
How much sunlight does the location get? Is it full sun? Part sun? Dappled shade? Dense Shade? The chart below defines what is meant by each of these light conditions.
| Full Sun | Area receives 6 or more hours of direct sun a day |
| Partial Sun | Area receives 4-6 hours of direct sun a day, with some of that sunlight occurring during the more intense afternoon period |
| Partial Shade | Area receives 4-6 hours of direct sun a day, with the sunlight being concentrated in the early morning or late afternoon when the light is less intense |
| Light Shade (Dappled Shade) | Sunlight is filtered through leaves, creating a shifting pattern of light and shadow |
| Full Shade | Area gets less than 3 hours of sun a day; may receive filtered light |
| Dense Shade | Minimal to no direct sunlight; often found under dense tree canopies |
It helps to observe the site at different times of the day over the course of the year. A site can be full sun early in the spring before the trees leaf out, but mostly shady once they do. If the site is partly sunny – does it get morning or afternoon sun? The more you can identify the various microclimates and match specific plants to those subtle variations within your planting area, the higher degree of success you can expect to reap.
2. Soil Composition and Texture
Soil composition refers to a mix of factors including the amount and types of minerals, organic matter, water and air present in the soil. The type of rock and climate from which the soil formed determines the amount of sand, silt or clay particles present, which in turn determines the overall soil texture. The soil texture affects how the soil will function – sand particles are larger which provides more air but less water retention, while clay soils are tightly packed which provides less air and greater susceptibility to compaction but also slows water drainage.
Once again, different plants are adapted to or tolerant of various types of soils, making this another factor to note when selecting plants for your garden. There are several tests you can do to ascertain the texture of your soil including the “feel” test and the “water jar” test. A simple Google search will produce numerous explanations of each of these methodologies. Most native plant lists indicate which types of soil – ie. Sandy, Loam, or Clay – a specific plant prefers, or will tolerate.
3. Acidity
The acidity of soil has a strong impact on the types of plants that will survive and thrive in your garden. Some plants will adapt to a wide range of acidity conditions, but others have distinct preferences – therefore it is an important factor to take into account. While you might be able to surmise the general level of acidity by paying attention to the types of plants that are “volunteering” in your existing site – for example, pines and rhododendron prefer acidic locations while honey locust trees prefer slightly alkaline soil – the best way to ascertain the exact acidity of your soil is by doing a soil test. The University of Maryland Extension provides a list of labs that conduct soil testing for a fee of $11 – $30 plus shipping costs. These services will also recommend amendments that can be made to your soil, however, selecting plants tolerant of the existing conditions is a simpler approach.
4. Moisture
A final factor to consider when assessing your site is the average moisture level of the soil. Some plants prefer “wet feet” making them great candidates for rain garden projects, while others prefer dry conditions and experience root rot if the soil is too moist. The following chart summarizes what is meant by each of the three categories of soil moisture levels generally cited.
| Wet | Wet soil is characterized by having all pore spaces filled with water, as occurs in areas with frequent standing water such as a rain garden or marsh. When squeezed, water will flow from the soil sample. |
| Moist | Moist soil holds water, but still has some air pockets. It will look damp. When squeezed the soil will form a clump but water will not drain from the sample. |
| Dry | Dry soil does not retain moisture and appears hard and lumpy. When squeezed the soil will crumble apart rather than form a clump. |
Once you have assessed your site conditions, select plants that are native to your ecoregion by the site conditions they prefer. This can be done manually by browsing through printed or online lists of native plants. Alternatively, the Alliance for the Chesapeake Bay has an online database that can be filtered by your selected site condition parameters.