Is that a Zone Map?
A zone map will help you determine where certain trees, shrubs and evergreens can grow. This map was created by the U.S. Department of Agriculture after it studied the amount of frost free days within the growing season over a forty year period. The map is used by nurseries and landscapers to determine what trees to plant and to sell.
Even with the map, these specific zones can experience variations, such as the amount of days in a growing season, the soil conditions, and the environmental conditions, all of which can affect the growth. Local differences are what affect landscapers. These must be studied before any planting can begin. Always work the plans out on paper after the area has been studied.
The plants for your scheme can be chosen from categories like shade, flowering trees, conifers, and flowering shrubs. It is always a good idea to try to and check with your agricultural college or local authority just to be sure.
Plants that are native to the U.S fall into the zones well, with distribution access zone lines.
Plants will tend to ignore zone line, you simply cannot tell a plant where to grow, there will always be some sort of variation. Exotic and imported plants, from Europe or the Orient are more variable. They may survive just fine in a certain area, but it is still best to check with a local nursery, no sense in buying expensive pieces if they will not survive.
It is a basic fact, that if a plant has survived over time in local nurseries it should do well in your landscape. However there are many plants that do require quite specific conditions to thrive. These plants include rhodendron, azealas, holy, and certain evergreens. These plants typically need an acidic soil or one free from lime or alkalinity.
In areas where the temperature is suitable but the soil is not, steps can be taken to incorporate materials with the soil to neutralize the alkalinity. Size, height, growth rate are all factors to use as a guide. The growth factors are directly linked to the soil condition. The length of the growing period is also a factor. Red maple will grow to greater dimensions in the south as a result of the longer season.
The maple, further east will not obtain the same statue, and more northern still, it is more restricted. These factors are important for determining the rate of growth, and this is why local studies are done. The conifers, tall spry evergreens, pines and spruces, are often more localized than the deciduous trees which drop their leaves. Some varieties are very hardy, while others are much tenderer.