Plant Information Fact Sheet No. 8

SITE INVENTORY AND ANALYSIS FOR LANDSCAPE DESIGN

Through the process of site inventory and analysis, you can determine elements and conditions that will impact the ultimate use and design of your landscape. Design, when based on thoughtful inventory and analysis, can improve the environment, by creating new features based on the users’ needs and keeping those features which are deemed useful and desirable.

WHERE DO WE BEGIN? Identify and locate all site elements on your property by size, material and condition. Find out the history of the site, how it once was used and if such use is still relevant today. Who will use the area and what ideals and activities are to be incorporated into the ultimate landscape design?

LOCATE IMPORTANT ELEMENTS: Walk your land with a scale-drawn property survey and roughly locate important built elements such as walks, driveways, utilities and fences, as well as natural features like existing trees and shrubs, rock outcroppings, and on and off-site views.

UNDERSTAND ECOLOGICAL SYSTEMS: As it is best to treat natural systems with regard, discern how natural areas can be maintained and where they are most vulnerable.

INVENTORY FACTORS THAT AFFECT CLIMATE: It is essential to inventory the prevailing wind directions, patterns of sun and shade, existing topography and soil type on a site in order to identify the different "microclimates" that exist.

FOLLOW THE SUN’S PATH: One of the best ways to improve certain site conditions is to understand the sun’s path across the entire area. For example, a house with southern exposure will benefit from the strategic placement of deciduous shade trees along the southwest corner; to lower the amount of heat and glare received on summer afternoons.

CLIMATE/MICROCLIMATE: In southeastern New York and the surrounding area, weather systems most often approach from the west. In summer, prevailing southwestern winds bring cool breezes, often moderating afternoon temperatures. The severe northwestern winds in winter make the areas that face north and northwest very cold. Precipitation is usually moderate and distributed more or less evenly throughout the year with about three inches of rain falling each month. During the hot summer months, when the evapotranspiration rate is higher than the amount of rainfall received, near drought conditions often occur.

SOIL COMPOSITION AND CLASSIFICATION: Soil is the result of decomposition of parent rock material. Soils are classified by physical and chemical properties, which include grain size and distribution as well as organic content. Soils are also categorized by their ability to support construction. Solid rock and boulders are the most suitable base for construction with fine sand, silt, clay and peat being the least suitable.

For most horticultural purposes, we try to achieve a good balance of particles so that water will enter the soil and be held until the particles release it to the plant roots. Generally, coarse, sandy soils are more permeable than fine-grained clay soils, but tend to lose water and nutrients too rapidly for plant roots to take up. Organic matter in soil improves nutrient content and prevents leaching, even after heavy rains.

SOIL pH: In addition to available moisture and adequate drainage, the most important property of a soil for horticultural applications is its pH level or soil reaction. The range of a soil’s acidity or alkalinity is expressed in pH values. A reading of 7 is considered neutral. Since all plants have specific tolerances for pH, a soil test is advisable to indicate the pH level. With this knowledge you can determine if a soil must be modified in order to grow desired species. Please note that most important nutrients become available for plant growth in a slightly acid soil with a pH of about 6.5. If a soil is quite acidic (below 5.5) then nitrogen, phosphorus, and potassium become virtually unavailable to plant roots while other nutrients such as iron, manganese, and boron become readily available. Only acid-loving plants such as Rhododendron and Azalea can tolerate and thrive in this type of soil. Many plants are also intolerant of alkaline soils and this can be more of limiting factor to growth than soil acidity.

VEGETATION: Trees and shrubs in the landscape are classified as coniferous, deciduous and broadleaf evergreen. Conifers include needleleaf evergreens like spruce, fir and pines along with ancient species like ginkgo and cycads. Deciduous trees like oak, maple, and beech compose much of our northeastern forests. Rhododendron and holly are examples of broadleaf evergreens.

For inventory purposes, it is important to note all trees over 4" DBH (diameter at breast height) and observe the size of their branching canopy. Next, locate all shrubs and inventory visual characteristics such as form, branching habit, twig character, bark coloration, foliage shape, texture and color, flower color and fragrance, fruit and distinguishing uses such as wildlife and human value. Lastly, identify plants in the understory layer including herbaceous perennials, biennials and annuals, ferns, fern allies, vines and/or seedlings of trees and shrubs. Noting the overall condition of the vegetation along with a thorough inventory will help you decide what you want to keep and what needs to be weeded out.

ANALYZE THE DATA: After you have carefully inventoried the natural and built features, you can begin to analyze what you wish to keep, what you will remove, what needs to be modified, and what will be added.

INTERPRET A SITE’S LIMITATIONS/POTENTIALS: Further emphasizing a beautiful, existing view is a great way to begin interpreting a site’s design potential. Similarly, noting an area that holds rainwater would limit it’s potential for development, unless you want to plant a wetland garden. 

BLUEPRINT FOR SUCCESS: The process of site inventory and analysis identifies and evaluates existing site conditions to determine what can be worked with and what must be overcome in order to accomplish the design proposal. The key is careful review of existing space and material so that a beautiful, functional and manageable landscape can evolve.

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