Plants need water, nutrients and sunlight to grow properly. Their growth changes when any one of these three factors is lacking. In this experiment we will try to measure the growth rate of a plant stem grown in the shade.
Things Required:
2 green onions
Glass
Soil
Ruler
Marking pen, red or black
Directions:
Measure about 6 inches (15 cm) from the root of each onion and ask an adult to cut off the stem.
Fill the glass with soil. Moisten the soil with water. Stick the closed end of the marking pen into the soil near the glass and move it back and forth to make a hole. The hole needs to be large enough to bury the onion root 2 inches (5 cm) below the surface of the soil.
Insert the onion, root down, into the hole. Push the soil around the onion to secure it in place.
Do this for both onions. Place the glass away from a window. Use the marking pen to colour around the end of each onion stem. Use the pen to mark the stems each day. The new growth will grow out of the outer skin covering.
Observe and mark the stems daily for 2 weeks.
This Is What Happens:
The stems may grow at different rates, but they can grow as much as 12 inches (30 cm) in 2 weeks.
Science Behind It:
Plants need water, nutrients and sunlight to grow properly. Their growth changes when any one of these three factors is lacking. The lack of sufficient sunlight causes a plant to grow very tall. Many bedding plants have very long stems because they do not receive enough sunlight. Trees in a thick forest are often thin and very tall so that they may reach upward to the sun. Your onion plant has grown very tall because of the lack of sunlight.
