Song Sok-ze
The author is a novelist.
In early spring this year, a friend sent word about a plum tree. Several years ago, he had gone south during plum blossom festival season to ride a bicycle and returned with a plum tree in a pot. This year, unlike in past years, that tree produced only one flower in February. By “past years,” he meant that the tree would usually open five or six blossoms with a faint fragrance.
Red plum blossoms, designated a natural monument, are in full bloom at Hwaeomsa Temple in Masan-myeon, Gurye County, South Jeolla Province, on March 31. The temple is holding a photo contest to coincide with the blossoms. [GURYE COUNTY OFFICE]
When I asked what might have happened, he said that last year he had carried out repairs on his apartment over several months. He guessed that the tree had been stressed by the dust and chemicals produced during the construction.
I could not easily understand that explanation. If a tree sensed danger because of environmental change, would it not bloom more, not less, to reproduce? I found it hard to grasp that a plum tree, because of renovation work, had reduced its effort to leave descendants.
That made me want to know how flowers bloom in spring: plum, cornelian cherry, cherry blossom, magnolia, forsythia, azalea, peach blossom, apricot blossom, pear blossom, apple blossom, bridal wreath and royal azalea, along with countless other flowers across mountains and fields.
Flowers bloom, needless to say, because of the plant’s instinct to reproduce. But because plants cannot move on their own, they need intermediaries such as insects, birds and wind to bring the pistil and stamen together so that seeds may form. Plants therefore produce alluring scents, bright colors and sweet nectar, offering a reward so that bees will carry pollen for them.
Plants that bloom also need warmth to accumulate for a certain period before their buds can open. The scientific term for this is “total accumulated temperature.” It refers to how much heat energy above a certain threshold has accumulated in the plant after dormancy is broken, often expressed as the sum of daily average temperatures through around February. Depending on region, weather and the individual plant, representative spring flowers are expected to bloom at around 80 to 100 degrees Celsius for forsythia, 100 to 120 degrees Celsius for azalea and 250 degrees Celsius for cherry blossom. These figures are used to predict flowering times, harvest dates and local flower festival schedules.
As decisive as temperature is light. The total amount of solar energy a plant receives in a day is measured as “total accumulated radiation.” Put differently, once a plant has filled the required total of light it receives while measuring the length of day and night, proteins within it send a signal about when it is time to bloom. Not only flowering, but also growth and crop yield are determined in proportion to this accumulated light.
More surprisingly still, most trees that bloom in spring decide much earlier, from the previous summer into autumn, how many flowers they will produce the following year. This process is called flower bud differentiation. Trees leaf out in summer, store nutrients through photosynthesis and then enter winter dormancy. If they were to pass the winter with leaves attached, water would escape through the stomata, and in severe cases, the tree might freeze to death.
Trees that survive, including temperate fruit trees such as apple, pear and grape, must also meet a required period of cold during winter, from after leaf fall until about February of the following year. This is called the “chilling requirement.” It refers to the accumulated hours of low temperatures required for a plant to bud and flower normally in spring. The exact figure differs by species, but many trees need 1,000 to 1,500 hours or more at around 0 to 7 degrees Celsius. If that requirement is not met, flowering is delayed, and yields decline.
Cherry blossoms are in full bloom in Bugwi-ri, Buksan-myeon, Chuncheon, on April 16. Known as the latest-blooming spot for cherry blossoms in Chuncheon, the village draws spring visitors each year with a 1.2-kilometer flower-lined road. [YONHAP]
After a process as complicated as reaching the FIFA World Cup final, the final decision on bloom time is made by the rise in spring temperatures. When trees have satisfied their chilling requirement, total accumulated temperature has reached a certain level, and accumulated radiation is also sufficient, the flower buds swell and the blossoms open. Every roadside tree standing there as if it were nothing at all is, in fact, moving according to such careful planning. How could one fail to call this a wonder of life?
Lately, climate change has brought ecological disruption. Warmer winters can keep trees from meeting their chilling requirement, while sudden spring heat can pull flowering times forward. One cannot help wondering how much confusion the trees must have endured, struggling to keep pace with increasingly erratic weather. They have never, unlike one species on Earth, claimed to be the lord of all creation and brought about a mass extinction crisis for themselves and their neighbors.
My friend, if you wish to feel reverence for life, quietly look at those trees standing there, flowering.
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
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