Agriculture Reference
In-Depth Information
dormancy, tree fruit buds can tolerate temperatures ranging from about
−15°F to −40°F (−26 to −40°C). During spring, the plants quickly lose their cold
hardiness and open blossoms are killed at about 28°F (−2°C).
Sites with warm springs but frequent frosts make tree fruit production
difficult. This is especially true for stone fruits and Asian pears, which
bloom earlier than European pears and apples. Trees located on north-facing
slopes bloom later than those in sunnier locations — an advantage where
spring frost damage is a problem. If your orchard is located on a frosty site,
late-blooming varieties provide a distinct advantage. You may also need to
provide frost protection during and shortly after bloom.
Locations near the ocean or along the eastern shores of large lakes are
often excellent for orchards. The water acts as a thermal shock absorber,
cooling the orchard and slowing bud development in the spring while redu-
cing the risk of spring frost. Because weather typically moves from west to
east in the Northern Hemisphere, western shores of lakes have less influence
on orchard temperatures than eastern shores. In northwestern Montana, for
example, sweet cherries are grown commercially in a narrow strip along the
eastern shore of Flathead Lake. Just a few miles away, sweet cherry produc-
tion becomes very difficult due to spring frosts. Likewise, the eastern shores
of the Great Lakes host varied and abundant orchards, made possible by the
moderating influence the water has on nearby temperatures. In general, the
larger the body of water, the greater its influence on temperatures.
Summer temperatures are important factors for cool-climate orchardists
in terms of the heat units available to produce and ripen fruit crops. While
most stone fruit varieties ripen wherever they can be grown in North Amer-
ica, some pome fruit varieties require long, warm summers to mature. In
short-season areas, early-maturing fruits are generally more reliable and
productive.
