Spring has finally arrived in my neck of the woods.  All at once, leaf and flower buds are forming on trees and plants which have been bare for months.  Flowering bulbs are emerging from their underground slumber. And the birds!!! They are everywhere and fill the air from dawn to dusk with their cheerful songs.  The sudden changes to the world around me inspired me to investigate the science of Spring. Here’s what I learned.

How Do Plants Know it’s Spring?

Plants and trees respond to light cues to know when Spring has arrived.  Like humans, plants have circadian rhythms. This video does a great job explaining circadian rhythms and how plants sense and respond to the seasons.

This video describes how sugar molecules that a plant produces through photosynthesis help regulate the plant’s internal clock.


That’s all well and good for plants above ground that can sense seasonal differences in sunlight, but how do bulbs growing underground know when to bloom?

How Do Flowering Bulbs Know it’s Spring?

Spring flowers such as crocus, tulips, hyacinths, and daffodils grow from bulbs.  Bulbs are miniature plants and contain food storage tissue to provide everything the plant needs to survive the winter.  When the bulb receives signals that Spring has arrived, it is able to produce roots, stems, leaves, and flowers.

The cue for Spring bulbs to bloom is temperature.  These bulbs require a period of cold temperature (often 16-18 weeks) in order to bloom.  In fact, you can “force” many bulbs to bloom any time of year. You can read more about how changes in temperature herald Spring in plants here.

You can experiment with bulbs anytime. One idea for how to use bulbs to demonstrate the process of plant growth can be found here. If your garden includes daffodils, the flowers are excellent for flower dissection. It’s really neat to be able to see the different parts of the flower and understand their role in plant reproduction.

What Causes the Smell of Freshly-Cut Grass?

While on my daily walks, I have noticed some of my neighbors mowing their lawns.  I just love the smell of freshly-cut grass! It’s such a distinctive smell, and I began to wonder what chemicals caused the scent.  I admit, I was kind of saddened to find out the reason behind the smell.

The Birds are Back!

Last but not least, the arrival of Spring has brought with it the return of many bird species.  I enjoy watching the birds in my yard, foraging, making nests, and filling the air with their song.  I always keep my phone handy so that I have access to my favorite app for bird-watching: Merlin Bird ID.  I’ve written about this free app before, but with the increased bird activity I thought I’d share it again.

To use Merlin Bird ID, all you need to do is answer five questions about the bird you wish to identify:

  • Where did you see the bird?
  • When did you see the bird?
  • What size was the bird?
  • What were the bird’s main colors (choose from 1-3 colors)
  • What was the bird doing when you saw it? Options include flying or soaring, on a fence or wire, eating at a feeder, swimming or wading, on the ground, or in trees or bushes.

Based on your answers, the Merlin app will generate a list of possible birds. The list isn’t random, but relies on a database of the most common species found in your location at the time you are using the app. Once you’ve identified your bird, you can read more about the particular species. You can learn its migration pattern and even listen to recordings of its song.

Results from the Merlin Bird ID app identifying the Carolina Chickadee and a map of its habitat
Pictures of American Goldfinch, Indigo Bunting, and Northern Flicker identified by the Merlin Bird ID app

I have thoroughly enjoyed using the Merlin app to help me identify species in my area including the White-breasted Nuthatch, American Goldfinch, Tufted Titmouse, Pileated Woodpecker, Indigo Bunting, Red-winged Blackbird, Northern Flicker, and many more. This is a great app for hobbyists, as well as for those with students studying birds (or biology, ecosystems, or animal behavior) in school. I love how easy it is to identify the birds that come to my bird feeder. It provides a much-needed break from my view of computer and phone screens, and helps keep me mindful of the big, beautiful world we live in. To learn more about the Merlin Bird ID app, click here.

What is your favorite part of Spring?

Further Reading

April Showers Bring…the Science of Spring

How Flowers Know it’s Spring

How Do Trees Know When It’s Spring?

Spring flowers blooming

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