The apple blossoms this past spring were the first hint of an unusual season – they were abundant and lovely. The crab nearest our house set fruit for the first time in a decade.
Then I noticed a black cherry blooming in a way I’d never seen before. From afar, it looked as if the tree were covered in thousands of white, downy pipe cleaners. Some of the flower groups were six to eight inches long, so long that the tree, which isn’t usually a noteworthy part of the spring spectacle on our farm, became a centerpiece.
Capping it off were the raspberry flowers – so numerous as to be inconceivable. Could there possibly be that many raspberries in our patch? By last month, the results were in. The harvest was set to exceed the previous three year’s combined. Canes were bent double under the burden of fruit.
The flower show this past spring was spectacular. The question is, why was it so spectacular? Why did so many trees and shrubs from so many different species put on such a great show?
Though there rarely is a single answer to such questions about the natural world, in this case, one answer jumps out immediately: last winter’s snowpack. The snow came early, stayed late, and covered the ground more or less continuously for roughly five months. As a result, the ground remained unfrozen across most of New Hampshire and Vermont. Despite winter low temperatures that did their usual dance in the teens and twenties below zero, the snow insulated the ground and kept it above freezing throughout.
This set the stage for a showy flower spring because, contrary to popular conception, trees and shrubs will continue growing all winter long provided the ground remains unfrozen. When the summer “growing season” comes to an end, perennial plants shift their attention from growing branches, setting leaves, and manufacturing sugar, and instead begin focusing on growing new roots and preparing for the following spring. This underground process continues until the ground freezes and makes new root growth impossible, both physically (frozen ground can’t be penetrated by new rootlets) and metabolically (tender young roots, like tender leaves and twigs, are more susceptible to freezing damage than older tissue).
In a typical Vermont or New Hampshire winter, the ground is frozen for two to three months, with our trees and shrubs waiting it out in dormancy. But last winter’s early and deep snowpack allowed many species to capitalize on the insulated ground and grow roots all winter long. This gave them the below-ground infrastructure needed to invest heavily in above-ground infrastructure the following spring.
As plants grow, there is a constant balance being struck between the growth we see above ground and what’s happening below. Last summer was a good growing summer hereabouts, with fairly regular and reliable rainfall. This led to plenty of sugar and moisture being manufactured and stored in roots. Last winter was also a good growing winter, allowing this sugar and moisture to be converted to new roots. This, in turn, set the stage for the above-average spring; the trees and shrubs had an expanded foundation of roots, along with ample sugar and moisture, to support extensive flower and branch growth.
A different snow winter can have just the opposite effect on trees. The most difficult snow scenario, from a tree’s perspective, is the one we had in the winter of 2006-2007: the snow was late and heavy. Much of our region had bare (or barely covered) ground right into January, allowing the ground to freeze hard. Then the snow finally came, effectively trapping the cold in the ground rather than insulating it out. Tree root growth was minimal, and the spring flower season was not especially memorable. Perhaps the contrast is what made this past spring so spectacular.
Not everything related to spring’s flowers is determined by the previous winter. Leaf and flower buds are set on trees and shrubs the previous fall, meaning that no amount of good winter growing can entirely overcome a poor previous summer. The weather during the spring itself also plays a role. In this case, this past spring started with lots of moisture from the melting snowpack and quickly transitioned into an unusually warm and sunny April, sort of a “perfect storm” for flowers.
Back on our farm, the fruit of that “perfect storm” of spring flowers came to an abrupt and unfortunate end last month. Those raspberry canes, laden with fruit by the combination of last summer’s rain and last winter’s snow? That record-breaking crop? We had just started harvesting it when a perfect storm of a different sort—an inch of hail—stripped the fruit and shredded the leaves. So much for the big spring.