Native to China but now widely grown as a fruit tree across many parts of the temperate world, peach trees (Prunus persica) produce flower displays that arguably rival those of cherry or crab apple trees. Without the peach blossom and subsequent pollination by honeybees, the peach fruit would not develop and ripen. For the peach tree to remain healthy and produce its flowers, it needs to grow in a sunny location in a fertile, moist, well-draining soil.
Peach blossoms comprise five petals and numerous tiny hairlike stamens. The petals range in color from nearly white to pale pink and medium pink, sometimes with a hint of lavender hues. The flowers are borne singly on the branch twigs, although many flowers can occur all along the branch to make it look like it is fully clothed in blossoms.
Peach trees are among the first deciduous trees to yield flowers in early spring. They appear before the tree leaves emerge. Depending on local climate, peach trees begin blooming as early as late February in the American Deep South (although March is most common), to early April in the coldest reaches of its winter hardiness range either in a higher latitude or elevation.
Once flowering begins on the peach tree, a large number of flower buds open each day the weather favors it. On cold, rainy/snowy days the flower buds are held tightly closed. Over the course of 10 to 21 days, flowers are open on the various branches on a peach tree. Certain varieties of peaches may have specific characteristics affecting their length of flowering display or age of flowers before they wane and drop petals. Moreover, warmer spring temperatures hasten or shorten the flowering season whereas a cool weather regimen prolongs the gradual display of flowers.
Peach trees, like other fruit trees in the rose family that are native to temperate climate regions, must undergo an annual process called vernalization. This prolonged exposure to temperatures between 0 and 45 degrees F initiates the internal processes that will produce flowers the following spring. Excessively cold winter temperatures can kill branch tissues and entire peach trees, and an insufficient number of cold days (called "chilling hours") can prevent formation of any flowers. Peach breeders have developed peach varieties that have "low chill hour requirements," resulting in trees that receive only a couple days of chilly weather still able to produce flowers. Such peach trees are grown where winters are typically too mild for standard peach trees, such as along the American Gulf Coast.
Threats to Flowering
Even though winter cold is required to produce the springtime flowers, this cold can lead to the demise of the flowering, too. Since peach trees bloom so early in spring, the blossoms are often susceptible to damage from ill-timed late winter and early spring frosts. Once the flower bud opens, the fragile and thin petals are easily killed by frost, and subfreezing temperatures will kill the male and female organs of each blossom. Flower buds that are small and not yet fully exposed to the air have limited resistance to freezing temperatures, but nonetheless can survive cold better than fully open blossoms.