While trees blossom and leaf out in the spring after being dormant during the winter, they actually form their buds during the previous summer or fall. In the winter, they don’t have the energy to grow structures that are small and complex. Sometimes it’s hard to see them, but if you look carefully in the fall, you will notice small buds on the branches of trees that will become flowers and leaves in the spring. Trees do all their growing in early summer. In late summer, they store up reserves to begin the growing process again the following spring.
Additional Resources: The Forest Academy
It is possible to force flowering trees and shrubs to bloom early by bringing them inside where it’s warm. On a mild day in late winter/early spring, prune a 30-60 cm (1-2 feet) length of branch from a flowering shrub (look for one where the buds are starting to fill out.) Cut slits in the stems so it’s easier for the branch to take in water and put the branches in a vase full of water. After a day, trim the stem at an angle and put it back in the vase. Keep the branches in a bright room (not in direct sunlight) changing the water frequently. Blossoms should appear in a few weeks, but it depends on the type of flowering shrub or tree. Forsythia tend to be quicker and easier to force.