All great gardens have one thing in common, they were thoughtfully planned before they were built. To plant a successful garden you must have a clear understanding of your site’s conditions. A thorough site analysis enables the gardener to make informed decisions regarding design and plant selection. Determined in this site analysis are the following factors; climate & micro-climate, sun & shade conditions, wind exposure, soil composition & chemistry and existing vegetation.
Plant hardiness zone maps divide the country into zones based on the lowest average winter temperature. A plant that is adapted to your hardiness zone is one that can tolerate the lowest winter temperature your zone typically experiences. Find out the zone in which you live and use it as guide during your plant selection process.
Along with the overall climate conditions of your area, micro-climates within your specific site also determine what is appropriate for your garden. Micro-climates are conditions, such as temperatures, which can vary from spot to in spot the garden. A sunny spot against a brick wall with a southern exposure, for example, will be warmer than its surrounding environment, even during the coldest winter days. In a space such as this, plants which are borderline hardy have a better chance at survival than if planted elsewhere in the garden. Also, however, a warm full sun location can encourage premature new growth on some plants which could damage new shoots if there’s a sudden drop in temperature.
The canopy of the existing trees can protect plants by reducing their radiant heat loss. In winter, the micro-climate beneath a tree may be several degrees warmer than the surrounding air, this slight difference in temperature can be beneficial to some plants. Furthermore, the tree’s shade during the early morning slows the rate of thaw in spring delaying the emergence of spring bulbs.
Sun and Shade
Being aware of the sun and shade conditions in your garden is critical to proper plant placement and, in turn, to the long term health of your plants. Improperly placed plants are a main reason for unnecessary transplants. Most plants prefer at least some shade during the day. Observe the light condition of your garden over the course of a few days to determine how much sun it gets. Be aware of the time of day as well. Many plants that thrive in part sun welcome shade during the heat of the afternoon, when the sun is strongest.
Types of Shade
Plants which demand full sun should be placed where they get at least 6 hours of each day. Shady conditions can vary. There are three types of shade; dappled, part shade & deep shade.
Dappled shade perhaps is the easiest type of shade in which to garden. It occurs beneath deciduous trees where there are drastic changes in the amount of sunlight reaching the ground throughout the year alternating between a patchwork of shade and sun in the summer and full sun during winter after the trees drop their leaves. Many shave-loving plants will adapt to these conditions. Many shade tolerant plants, such as trillium, epimedium, anemone and various bulbs have adapted to these conditions by flowering in the spring while there is still quite a bit of light entering the garden.
Part shade occurs as the sun moves across the sky. It creates situations such as full sun in the morning and shade in the afternoon. Only the most sun loving plants will fail to survive in part shade conditions. It’s perfect for those plants which tolerate sun but little shade. Afternoon shade in this situation is quite beneficial to plants, such as hydrangea, as the shade will protect them from the sun during the hottest part of the day. If the opposite is true, shade in the morning and sun in the afternoon, some plants will tend to look stressed as the coolness of morning shade gives way to full sun during the hottest part of the day.
Deep shade occurs beneath evergreens or in narrow spaces between tall buildings and can be a challenging environment in which to garden. Soil beneath evergreens is usually poor due to the lack of an annual leaf fall which in deciduous forests provides layers of organic mulch. Plants selected for deep shade gardens need to be shade demanding not just shade tolerant. These plants may tolerate some morning sun but not more than an hour or so of afternoon sun.