Reprinted with permission from Snackable Science Experiments by Emma Vanstone, Page Street Publishing Co. 2019. Photo credit: Charlotte Dart
You probably know that plants need sunlight, water, nutrients and the right temperature to grow. But did you know that plants can grow without soil? You can test this out by growing a cress head. Like humans, plants need water to stay hydrated. Have you ever noticed that a plant low on water starts to droop?
- 2 eggs
- Cress seeds
- Egg holder
- Markers for decoration
- Cotton balls
- Plants need sunlight for a process called photosynthesis, which requires energy in the form of light to convert carbon dioxide and water to carbohydrates for growth.
- Warmer temperatures encourage plants to germinate and grow, while in colder temperatures growth slows down or even stops.
- Soil contains all the nutrients a plant needs to grow, but it’s the nutrients the plant needs, not the soil itself.
- Hydroponics is when plants are grown in water that contains the nutrients it needs rather than soil. Hydroponics is a very useful growing method in areas where there isn’t much good soil or where space is limited.
- Boil the eggs until they are hard-boiled, about 6 minutes, and leave them to cool. Carefully slice off the tops of the eggs, remove all the egg whites and yolks and rinse out the shells. Put the shells in the egg holder.
- Using markers, decorate your eggshells to look like superheroes. Dampen a cotton ball and place it inside the eggshell.
- Place 10 to 15 cress seeds on the cotton wool and put the superhero egg in a sunny spot.
- Once the leaves on the cress turn green, you can eat them.
Place plastic cups over the eggshells to act like a greenhouse. Design an investigation to discover whether the cress grows better with or without the greenhouse.