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Description

This activity was all about growing plants without soil (hydroponics) in space, and why gardening is important to space exploration. What would happen if we tried to grow plants in space without hydroponics? How do astronauts take care of plants if they don't have soil?

Growing plants in space helps us to see if it would be sustainable to grow food in space, such as for astronauts. What do you think are the other challenges of growing plants in space?

You also made a soil-free bottle planter. What was challenging? Do you think your seeds will grow? How will you look after them?

Resources

Empty plastic bottles
Scissors
Cotton wool
Plant food
Water
Small plant seeds, such as lettuce, herbs or other fast-growing plants

Instructions

Planning and setting up this activity
Ask everyone in plenty of time to bring their own suitable bottle.
Make sure to protect any surfaces, such as with tablecloths or newspapers. You may also want to run this activity outside.
Running this activity
Gather everyone together and explain what hydroponics is. Hydroponics involves growing plants in a porous material (other than soil) and allowing water containing nutrients to filter through it (Source: BBC Bitesize, 2025).
Tell everyone that watering plants in zero-gravity is difficult for lots of different reasons. Researchers have also discovered that plant roots grow differently in space, due to the lack of gravity, making watering more difficult. Astronauts can't use a watering can like here on Earth, as the water would just float away. Instead, astronauts use a syringe to inject water directly into ‘plant pillows’ (special bags that contain seed and fertiliser) which are put into the Vegetable Production System (known as Veggie). Since 2014, astronauts on board the International Space Station (ISS) have had a special ‘Veggie’ garden and have managed to grow everything from lettuce to radishes to flowers, with varying degrees of success (Source: BBC Bitesize, 2025).
Now, it’s time to make the soil-free bottle planter.
First, remove the lid and carefully (with adult supervision) cut the bottle in half around the middle. Be careful of hands and fingers when cutting.
Next, place the top half of the bottle (the lid-end) into the bottom half of the bottle, with the lid end pointing down.
Add a layer of cotton wool onto the base of the top part of the bottle. This acts as a base for the plant roots to grow into and helps absorb water. Make sure the cotton wool’s thick enough to support the seeds and water but will still allow the roots to grow.
Gently press several seeds into small holes made in the cotton wool.
Remove the top half of the bottle.
Mark a line on the bottom bottle around 3-5cm from the base.
Fill the bottle with water up to this line.
Next, mix the plant food following manufacturer’s guidelines and add to the bottom part of the bottle.
Place the top half of the bottle back onto the base and wash your hands thoroughly after handling plant food.
Place the bottle in an area with lots of natural light. The water will rise through the cotton wool to water the seeds.
Check the hydroponic system every day and add more water as needed if the cotton wool dries out.

Tags

• Plants
• science

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