Tulip Test Gardens

Snow Blankets the Earth
How Does it Affect Bulbs?

How might a cold blanket of snow affect Journey North Tulip Gardens? As tough as tulip bulbs are, they contain some tender plant parts. Is snow cover likely to freeze and damage them . . . or does it play another role? YOU solve the mystery! Look for clues in these experiments done by Journey North students.

  1. Look at what students in Alaska found:
    They dug a deep cube-shaped pit in the snow. Next, they stuck four thermometers into the snow about four inches apart. Each one was deeper than the next. Here's what they found:

    Snow Depth Temperature
    Courtesy of University Park Elementary
    0 cm deep 8.6 degrees F (-13 degrees C)
    12 cm deep 12 degrees F (-11 degrees C)
    23 cm deep 16 degrees F (-9 degrees C)
    40 cm deep 25 degrees F (-4 degrees C)

  2. Look at what another group of Journey North students discovered one winter. They tested temperatures above and below the snow for two weeks in February. (Click on each graph to enlarge it.)

    Temperatures above the snow
    Temperatures below the snow

Journaling and Discussion Questions

About the graph from the first group of students:

  • What does the data tell you about snow depth and temperatures? Was it warmer or colder the further down they went?
  • What was the temperature difference from 0 to 12 centimeters down? From 0 to 40 centimeters down?

About the graph from the second group of students:

  • What do these graphs tell you about temperatures below the snow?
  • What is the high and low temperature on each graph? What is the temperature range (highest minus lowest)?
  • Do the temperatures vary more above or below the snow?

Your conclusion: Do you think that deep snow is more likely to damage or protect your bulbs? Explain your thinking.

Here's the scoop:
The soil gives off some heat. Fresh, uncompacted snow has 90 to 95 percent air trapped between its crystals. Because the air can barely move, it can't easily transfer heat away from the soil or cold down into the soil. The deeper the snow, the more it insulates the ground — and the plant parts beneath it. The temperature below fresh snow increases by about 2 degrees F for each inch of accumulation.

Dig Deeper

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