Stella Otto: The Backyard Fruit Gardener

Today's Tip: Mow vegetation short around the base of fruit trees and bushes to reduce winter habitat for rodents.

Choosing Fruit to Grow in Your Climate

One major envi­ron­men­tal char­ac­ter­is­tic to con­sider in regard to your gar­den is cli­mate. This can be bro­ken down into sev­eral areas of concern:

  1. the gen­er­ally expected cli­mate in your area
  2. a period of cold chill­ing required by the plant
  3. the micro­cli­mate estab­lished by cer­tain char­ac­ter­is­tics unique to your property
  4. 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

Micro­cli­mate

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.