One major environmental characteristic to consider in regard to your garden is climate. This can be broken down into several areas of concern:
- the generally expected climate in your area
- a period of cold chilling required by the plant
- the microclimate established by certain characteristics unique to your property
- length of growing season
General climatic considerations include an area’s average minimum temperature, rainfall and, in some cases prolonged high heat. Annual average length of the growing season is also important. Most fruit trees and bushes can grow in atypically hot temperatures for short periods, but may quickly suffer cold damage in zones much colder than that for which they are adapted.
The Need for Cold
Although temperate zone fruit trees and berry bushes cannot withstand excessive cold, they do require a certain amount of cold temperature to satisfy their dormant rest period needs. This time spent between 45 F and 32 F is know as the chilling requirement. If you live in the warmer climate zones of the United States (mainly parts of Florida, California, and the southwest) it is important to pay attention that you are choosing specially adapted varieties with low chilling requirements or your plants may not produce the expected fruit crop. Sometimes locating plants in the bottom of a valley where cool air collects may provide a microclimate that offers a small amount of additional chilling
A factor that can affect the average minimum temperature is location close to a large body of water. Because large bodies of water tend to cool down more slowly in the fall and warm more slowly in the spring, they minimize temperature extremes and have a stabilizing effect on the fruit production capabilities of the adjacent land within several miles of their shorelines. This is often referred to as a microclimate. Large areas of microclimate are found in Washington, California and Oregon as well as along the west shore of Michigan, New York and Ontario where winds are moderated as they pass over the Pacific ocean or Lakes Michigan and Erie influencing the climate that has allowed for development of major commercial fruit production regions.
In your yard., major prevailing wind directions, sheltered spots near heated buildings, tall thick hedge rows of existing trees, and areas of higher and lower elevation may create small microclimate areas. The most obvious microclimates in your yard will probably be caused by variations in elevation. You may notice in early spring and late fall, that areas of lowest elevation in your yard are prone to be the most frosty. Conversely, higher areas escape light frosts.
Look carefully at the surrounding topography as well. What may appear to be a high spot in your yard can still be very low relative to the surrounding area. If your yard sits in a bowl sur– rounded by higher ground, cold air will collect at the bottom of the bowl and you should select the later flowering fruits or varieties. This is important to be aware of. Your fruit tree’s blossoms, and ultimately the size of your fruit crop, will be influenced by how successfully it avoids being damaged by spring frosts. How completely some varieties mature for harvest will also be influ– enced in some years by how early they are subjected to hard frosts in the fall.
Another major influence of microclimate in your yard can be your house. Often, locating a tree close to the house, especially when it is on a side protected from the wind, can give the effect of being in a warmer microclimate since the house gives off a certain amount of heat. Also, if the tree is placed on the south side of a building where it is sheltered, but exposed to the most direct and intense sunlight, it may act as if it were growing in a warmer microclimate. In warm southern areas this may prove to be more heat than the tree is able to withstand. In a northern climate this can be an advantage by providing a bit more heat for the tree. Conversely, it may also cause it to break dormancy and bloom earlier leaving it susceptible to damaging frost.
Large hedge rows of tall trees in the vicinity of your planting site will have an effect as well; they may help shelter your yard from strong winds, but they also inhibit air movement. This can lead to cold frosty areas or “frost pockets” on the hedge row’s leeward side. Take this situa– tion into account, even though the tall trees may actually be on your neighbor’s property.
Length of Growing Season
The length of the growing season in your area also has an effect on which type and variety of fruit would be most productive for you. “Frost Free Days” is a term often used to define the length of the growing season in a given area. It is handy information to have so that you can choose varieties that will bloom, produce fruit and be harvested without damage from major frost. Fortunately, a record of frost free days has been statistically determined over many years of record keeping by various government agencies and will give as accurate information as you need at this time. Take a look at a map of growing season lengths and searchable spring and fall frost date data.
©2013. Adapted from the Backyard Orchardist: A complete guide to growing fruit trees in the home garden by Stella Otto.