Garden on a windowsill

You don't need a plot of land to show your child how plants grow. All you need is a jar of water, a few toothpicks and a potato or an avocado pit. Take the avocado pit or potato and insert three toothpicks into its center from three sides. Place the pit in a jar of water. Supported by the toothpick, the pit or potato should stand upright and be about half immersed in the water. Place the jar on the windowsill. In a week or so, roots should begin to grow downward in the glass while a central shoot and leaves will begin to grow upward. When sufficient roots have grown, help your child transfer the growing plant into a pot of soil. This activity introduces your child to botany, demonstrating how roots absorb water and anchor a plant in the ground.

For further exploration, check out the following books:

The Reason for a Flower by Ruth Heller (Putnam Juvenile, 1998)
A Seed Grows: My First Look at a Plant's Life Cycle by Pamela Hickman, illustrated by Heather Collins (Kids Can Press, 1996)