Is Plant Science Dead in Winter?
November 02, 2011 | 11:11 am
We understand that a walk outside on a beautiful spring day is a great addition to a lesson on plant and soil science, but plenty of opportunities inside the classroom can enhance learning, even when it is not so pretty outside.
Winter can be hard on plants, but most have an interesting system for survival. Lessons about how plants cope with temperature changes work well with later science lessons about photosynthesis, nutrient storage, or even frozen water expansion. Moreover, even with colder temperatures, teachers should not shy away from hands-on activities. Students can still perform fun activities, even if you cannot take them on a walk through an outdoor classroom or garden.
Some tubers and bulb plants, such as potatoes and onions, collect nutrients during the summer and autumn in underground storage organs. During the chill of winter, these storage facilities protect the plant’s nutrients, enabling it to grow back when the temperature warms. The following spring, these organs push leaves and shoots above the ground and begin the growing cycle again. Illustrate this concept with your students by encouraging a few bulbs to bloom indoors during the winter. Master Gardener Dee McKenna suggests visiting the local garden center as soon as bulbs arrive. Select large, firm bulbs. Small, bruised, and soft bulbs may not sprout, causing some disappointment in the classroom. McKenna also suggests forcing Triumph, Double Early, Single Early, and Darwin Hybrid tulips, as they are the easiest to force. Use a deep glass container and plant a tulip bulb close to the glass wall so that students can see the root system and the cycle of the bulb. Since glass containers normally do not have drainage holes, do not over-water. Before the bulb will begin growing, you must provide a six-week chilling period to stimulate winter. To do this, put the bulbs in a paper bag and store the bulb in a refrigerator crisper drawer, but do not put them next to fruits, which emit ethylene, a gas that hinders flowering. After the six-week chilling period, place the bulbs root end down so their tops (the narrower end) sit just below the rim of the pot. Cover them with enough soil so that the bulb noses are showing. During the dreary winter months, you will be able to brighten your classroom with growing tulips and provide students with a pretty example of nutrient storage, development cycles, and perennials.
Like hibernating animals, some plants survive winter through resting stages. Annuals, for instance, produce seeds that survive the winter and germinate the following spring to begin again the same cycle of growing, reproducing, and dying through the next spring, summer, and fall. An effective visual for showing this annual grow cycle is to find a sunflower head with the stem still intact. Sunflowers are usually available at local florists, or check a craft store for a fake sunflower. Pretty to look at, sunflowers have large, easy-to-see seeds and thick stems that make them easily accessible to students. Have students pass around the flower as you discuss the growth cycle of the annual. Of course, serving sunflower seeds as a snack adds another dimension to the fun. Refer to the Nutrients for Life Blog for great information on seed harvesting (link to Dee’s Blog on seed harvesting).
Additionally, our Nourishing the Planet in the 21st Century elementary curriculum provides detailed lessons that allow each student to grow their own plants in the classroom. This project in Lesson 1, Activity 2 of the curriculum gives students hands-on experience with plant growth and deepens their understanding of how plants and their environment interact. Some tips for growing seeds in your classroom include using bricks to hold fluorescent lights if you do not have a windowsill, just add or remove bricks to adjust the height, and use clear plastic cups for growing the seedlings, which allow the students to see the soil and the developing root systems of the plants. Finally, enforce these learned concepts with our new set of flashcards, which complement our Smithsonian-reviewed curriculum.