By Heidi Lewis
The cuckoo clock at the Greenwich Mean Time offices popped its head out at 11:02 a.m. on March 20, letting all us inside people know that it’s officially spring. For the outside world, the tightly wound mechanisms of nature's internal clock are springing plants into action. Petals and birdsong may fill the air, but spring is a delicate interval when seedlings and fruit tree blossoms establish themselves for the fruitful seasons ahead.
A warm winter can trick the blossoms into emerging early. A late spring storm can knock the tender blossoms to the ground or trample tender seedlings. This is why spring is the trickiest season for farmers. Their ability to balance instinct, experience, and weather predictions will help them determine when to take seedlings from the greenhouse after the danger of frost.
Fruit trees’ success depends on winter. They require a certain number of chill hours to garner enough rest-time to produce fruit. Their genetic alarm clocks vary from species to species. Apricots may require 500–700 hours below 45 °F, pluots only around 400, and some apple varieties as much as 1,400 (that’s 58 days). The vast matrix of thousands of fruit varieties projected against the myriad climates and microclimates in our country ensures us a bounty of fruit over most of the year.
The planet has rung the bell for the half-time show—the vernal equinox and the broadening of the days. Yet the time differs for each region’s ticker-tape parade of petals floating in the air and chorus of birds ushering the heroes onto the field. Plants have their own clocks—quiescence tells them when to start fruiting—and if you put your ear to a tree, you just might hear it ticking.