Tulips Need to Grow
Gathering Local Spring Tulip Data
plants, tulips need sunlight, warmth, and moisture in order to grow. In
the spring, soil, air, and water temperatures rise; snow melts; and rainfall
typically increases — setting the stage for plant growth, animal
migrations, and other biological changes. All
of these seasonal changes are driven by shifts in the amount of available
sunlight (called daylength or photoperiod) and its intensity (related
to the angle at which it strikes the Earth).
all emerge when the soil reaches a set temperature? Will tulips emerge
if there's still snow on the ground? Your students' questions won't all
have one "right" answer. That's what will make their investigations
are some interesting things scientists do know:
to cool underground winter temperatures for at least 12 weeks is the
most important factor affecting tulip emergence.
is not important for tulips to emerge or bloom. (It does affect
many other plants.) But daylength influences temperatures and other
factors, which, in turn, affects tulips.
temperatures when tulip flower stems are lengthening result in longer
(but weaker) stems. Colder temperatures result in shorter, sturdier
generally won't grow at all at temperatures below 40 degrees.
As you trace
all of tulips' basic needs grow back to the sun, students may wonder,
What does the sun have to do with rainfall? Below is a brief
explanation of the sun-driven water cycle and links to simple activities
you can conduct in class.
In the spring,
the sun warms water from oceans, lakes, and rivers. Warm water evaporates,
turning into a gas called water vapor. Vapor rises. As it does so, it
cools off. That causes it to condense — turn back into drops of
water — and form clouds. Cool air cannot hold as much moisture as
warm air. As the droplets in the clouds get larger and larger, they fall
back to Earth as rain or snow. (Sun-warmed air also helps create wind,
which helps move clouds and rain.)
You Know . . . ?
Water never goes away, but is constantly recycled. In fact,
a water molecule in your shower or glass might be the same one that
an early ancester used to water crops, or that people in a far away
country used to wash clothes a thousand years ago. Stranger yet,
it may be one that a dinosaur once sipped!
You can dig
deeper on these Web sites: