Spring in Wisconsin rarely arrives all at once.

One week brings warm sunshine. The next, a return to colder air. But even as temperatures fluctuate, something steady is happening overhead.

The trees are waking up.

Long before full leaves appear, trees begin responding to subtle seasonal shifts — changes in light, temperature, and time. These early signs are easy to miss, but they mark the true beginning of spring in the woodland.

At the Garden, this transition is already underway… spring doesn’t begin with flowers, it begins in the trees!

It Starts with Light

While warmer temperatures get most of the attention, trees are actually responding to something that’s way more consistent: daylight.

As days grow longer in early spring, trees begin adjusting their internal cycles much like we do. This process that’s guided by light is what triggers the earliest stages of growth in trees everywhere.

This matters in a place lik Wisconsin where spring weather can be unpredictable. Even during colder stretches, trees are already preparing for the season ahead.

Buds Are Ready to Go

What may look like bare branches are anything but dormant.

Tree buds formed last year, holding the leaves and flowers that will emerge this spring. All winter, those buds have been protected and waiting for the right conditions.

Now, they’re beginning to change.

Look closely and you may notice:

• Buds swelling slightly
• A shift in color from deep brown to green or red
• A softer, fuller shape at the tips of branches

These small changes signal that growth is already in motion.

The First Green Haze

One of the most subtle and eye-catching moments of spring is when trees begin to leaf out.

Before leaves fully expand, there’s a brief period when the canopy takes on a soft, light green glow. It’s often described as a “green haze” — a sign that leaves are emerging but not yet fully formed.

This phase doesn’t last long. Within a few weeks, the canopy fills in, shade increases, and the landscape shifts again. Seeing this transition is one of the rewards of visiting the Garden early in the season.

Early Activity in the Trees

Some trees make their seasonal shift more visible than others.

You may notice:

• Maples beginning sap flow during warmer days
• Willows and aspens producing soft, fuzzy catkins
• Early flowering trees adding subtle color before leaves appear

These early changes help support the rest of the ecosystem. They provide food for insects and signal seasonal shifts.

Why This Moment Matters

The timing of tree growth affects more than just the canopy.

Before leaves fully emerge, sunlight reaches the forest floor which fuels the brief bloom of woodland ephemerals like trillium and bloodroot. Pollinators rely on this timing, as do many other plants and animals.

Trees don’t just respond to the season — they shape it. Their timing influences how the entire woodland ecosystem unfolds.

What to Look for at the Garden

Right now, the Garden offers a chance to see this transition up close.

Look for:

• Swelling buds along walking paths
• Light filtering through still-open canopies (especially in the Shade Garden!)
• Early movement in branches and understory plants
• Subtle color shifts as green emerges

Woodland-inspired spaces throughout the Garden highlight these layers — showing how trees, groundcovers, and seasonal plants work together.

And because spring unfolds week by week, each visit offers something new.

Experience It Through Woodland Wonders

This season, Woodland Wonders presented by Selner Tree & Shrub Care invites you to experience these changes more intentionally.

Throughout the exhibit, you’ll find opportunities to look more closely at how woodland systems work — from the earliest signs of tree growth to the layers that support life below. It’s a chance to slow down, observe, absorb, and better understand how everything in the landscape connects.

A Season in Motion

Spring isn’t a single moment. It’s a process.

Before the full canopy, there’s this quieter phase of transition. Trees lead the way, responding to light and time long before we fully notice.

Take a moment to look up, notice buds, branches, and early growth. This offers a different way to experience the season!

It’s already happening, and it’s worth seeing now.

Sources & References

• University of Wisconsin–Madison Arboretum — Seasonal plant cycles and woodland ecology
• University of Wisconsin Extension — Tree growth cycles and phenology in Wisconsin
• Wisconsin Department of Natural Resources — Native trees, seasonal changes, and forest ecosystems
• USDA Forest Service — Tree physiology, bud development, and seasonal growth patterns
• Harvard Forest — Phenology and timing of leaf-out in temperate forests