Long before you spot the first daffodil or notice buds swelling on trees, plants have been quietly preparing for spring in ways we never see. These hidden processes start deep in winter, happening inside buds, beneath the soil, and within plant tissues while everything looks completely dormant.
1. They’re counting chilling hours like a biological clock.
Plants have what’s called a “temperature memory” that tracks exactly how many hours they’ve spent in cold temperatures between roughly 0 °C and 7 °C. Most trees and shrubs need to accumulate between 200 and 1,000 chilling hours before they’ll break dormancy, which stops them from waking up during those deceptive warm spells in January that would leave new growth vulnerable to later frosts. They’re literally keeping track of time through biochemical changes, and until they hit their required number, they won’t respond to warmer weather, no matter how inviting it seems.
2. Dormant hormones are slowly changing in the background.
Throughout late autumn and winter, plants maintain high levels of abscisic acid in their buds, which is the hormone that keeps them dormant and prevents premature growth. As winter progresses and chilling hours accumulate, these levels gradually drop without any visible change to the plant. Once abscisic acid decreases enough, growth-promoting hormones can finally take over, but this entire hormonal change happens weeks before you’d notice any outward signs of spring activity.
@treesandbugs Arborist Term of the Day – Abscisic Acid (ABA) – Abscission – Abscission Zone – #arborist #trees #greenscreen ♬ original sound – Tree Cozy
3. Starch stored in roots is converting to sugar.
All through autumn, plants moved sugars from their leaves down into their roots and stems, converting them to starch for storage. Now, as temperatures start warming even slightly, enzymes begin breaking that starch back down into soluble sugars like sucrose. This conversion happens invisibly inside root tissues and stems, creating the fuel that will power the explosive growth of leaves and flowers when spring properly arrives, but you’d never know it was happening just by looking.
4. Flower buds are actively accumulating starch despite looking completely inactive.
Research on cherry trees showed that flower buds that appear totally dormant are actually incredibly busy inside. Ovary cells within flower buds steadily accumulate starch throughout winter, with levels increasing in direct correlation with chilling hours. This starch build-up happens at a precise developmental stage and reaches maximum levels right when chilling requirements are met, then vanishes as the buds prepare to open, but from outside they look exactly the same the entire time.
5. Sap is starting to flow through freeze-thaw cycles.
On days when temperatures rise above freezing, but nights still drop below zero, something remarkable happens inside tree trunks. The freeze-thaw cycle creates pressure changes that push sap upward from roots into branches, which is why maple syrup producers can tap trees in late winter. Gas in the xylem vessels expands when it warms and contracts when it freezes, creating a pumping action that gets sap moving weeks before leaves appear, but you’d only notice if you cut into the bark.
@toddwhiller When does sap run? Just some more fun facts! #sap #maplesyrup #ctfarm #mkf #farm #farmlife #maple #tree ♬ Thank You for Being You – OctaSounds
6. Roots are growing and absorbing water underground.
While everything above ground looks dead or dormant, roots continue growing and taking up water through winter whenever soil temperatures stay above freezing. Root systems actively extend and search for nutrients beneath the frozen surface, preparing to support the massive canopy that will develop in spring. That underground activity accelerates as soil warms, with roots racing to establish themselves before the energy demands of leaf and flower production kick in.
7. Cell membranes are being maintained and proteins rebuilt.
Dormancy isn’t total shutdown but more like deep maintenance mode. Throughout winter, plants are repairing cell membranes, breaking down old proteins and rebuilding new ones, and generally keeping their cellular machinery in working order. It’s similar to how our bodies restore themselves during sleep, except plants are doing it for months while looking completely lifeless from the outside.
8. They’re switching from deep dormancy to a waiting state.
There are actually two types of dormancy, and plants transition between them invisibly. Endodormancy is when internal signals keep growth locked down regardless of external conditions, but once chilling requirements are met, plants transition into ecodormancy where they’re simply waiting for warm enough temperatures. The switch happens entirely through internal biochemical changes, so a plant in January and a plant in March might look identical while being in completely different physiological states.
@sweetlifeflora Did you know that most plants will go through a dormancy period in the winter? This is called WINTER REST. ❄️🪴 Follow for more plant care tips! #plantiktok #planttoktok #plantobsessed #plantslife #plantslover #plantobsession #babygroot ♬ Shootout – Izzamuzzic & Julien Marchal
9. Buds are developing internal structures long before they swell.
Inside what looks like a tight, hard bud, leaves and flowers are already forming at a microscopic level. Cell division and tissue differentiation happen months before bud scales crack open, with intricate structures like petals, stamens, and leaf veins slowly taking shape. By the time you notice buds starting to swell, they’re actually in the final stages of development that’s been progressing invisibly since the previous summer.
10. Sugars and nutrients are being transported upward in preparation.
Water and dissolved nutrients stored in roots begin moving up through the plant’s vascular system weeks before visible growth starts. This movement happens through a combination of root pressure and the physical properties of water molecules clinging to each other in narrow tubes. The plant is essentially filling its plumbing system and positioning resources where they’ll be needed, creating the infrastructure for rapid spring growth that seems to appear overnight but actually required weeks of hidden preparation.