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Tomatosphere™ uses the excitement of space exploration as a way to teach the skills and processes of scientific inquiry. In the Seed Investigation, students examine the effects of the space environment on the germination of tomato seeds.

As humans seek ways to travel deeper into space, we must discover ways to expand life-support systems. One possible solution is a plant-based system. Tomato plants are an ideal choice as they provide wholesome nourishment and water through transpiration from their leaves. Through photosynthesis, tomato plants also convert light energy and carbon dioxide exhaled by astronauts into oxygen that is needed for survival.

Tomatosphere™’s Seed Investigation includes planting two sets of tomato seeds (one exposed to space or space-like conditions and the other untreated), examining and recording the germination of seeds, and submitting the results. Follow the step-by-step guide below.

The Seed Investigation Question

How does exposure to the space environment or space-like conditions affect the number of tomato seeds that germinate?

Scientific Inquiry and Tomatosphere™

Tomatosphere™ offers an excellent opportunity to have your students think and act like scientists as they practice their inquiry skills and develop understandings of the nature of science and the concept of a fair test.

As students engage in the steps of the Seed Investigation these skills can be introduced and practiced with the support of a variety of resources and suggested learning experiences that are appropriate to different ages and levels of understanding.

student with seeds

In the Seed Investigation, students will compare the number of seeds that germinate from two sets of tomato seeds. One set of seeds have been sent into space or treated in space-simulated conditions (“treated” seeds), and the other set of seeds (the “control” seeds), have not been to space or been treated in space-simulated conditions.

Tomatosphere™ Models a Fair Test

The simple and well-designed Seed Investigation is a valuable tool for modeling a fair test. Fair testing is a key component of scientific inquiry and a common method used by scientists world-wide to provide evidential proof of their ideas and theories.

Learn about scientific inquiry, fair testing and the nature of science

Tomatosphere™ is a Blind Test

As part of ensuring a fair test, you will not know which of the seeds have been in space, or if they have been treated or untreated, until the germination process is complete and results are submitted.

Step 1

Register and/or Order Seeds

When you go to order seeds, you'll be registered with a Let's Talk Science account if you don't have one already.

Order seeds

Step 2

Review and prepare the program materials

A. Familiarize yourself with the Tomatosphere™ resources

We recommend that you read through this guide and explore resources that support this guide. These learning resources provide opportunities to introduce and extend the learning beyond the Seed Investigation and offer suggestions on how to develop skills of inquiry and cross-curricular concepts.

Explore supporting online/print resources

B. Plan a time to do the Seed Investigation

Initiate the planting of seeds on Wednesday or Thursday. It usually takes 5-7 days for the first seeds to germinate and students should then be present to see the first visible signs of germination.

Do not plant the seeds prior to a school break, such as the traditional spring break or religious holidays, when you might not have the opportunity to water the plants properly, or when the temperature in the school may be lowered (which may affect growth).

C. Schedule the planting and observation

Task or Event

Estimated Timing

Seed planting

40-60 minutes, depending on the age of students

Observing, measuring and recording

5-10 minutes per day, every day preferably at the same time each day


5 to 7 days in ideal conditions, but can take up to 3 to 4 weeks

Once germination has occurred and the results are submitted, the plants may be transplanted to pots or outdoors, depending upon local conditions.

Discover age-appropriate extensions from grade-based resources

Learn more about transplanting and growing tomatoes

Tomatosphere Starter Kit ™

A Tomatosphere™ partner, Stokes Seeds® offers an optional starter kit available online at

D. Obtain and prepare the materials you will receive from Tomatosphere™

You should receive two packages of seeds (marked with two different letters). One package contains the "control" seeds (untreated) and the other package contains the “experimental” seeds (treated), which have been exposed to space or space-like conditions.

You will be provided with

  • 2 Tomatosphere™ seed packages per classroom (25-30 seeds per pack), each labelled with a different letter (e.g., A and B)

You will need to provide

  • 50-60 planting containers (or two large seedling trays)
  • 50-60 peat pellets (one seed per pellet) or enough potting soil for 50 – 60 small pots
  • Water and watering pots/cans
  • A space in the learning environment that provides adequate germination conditions
  • Observations recording table (See Learning Strategies for additional templates and exemplars)
  • Results Summary (for results submission)

Get planting containers

Containers should be at least 7.5 cm (3”) deep to allow for roots to grow. Yogurt cups, plastic take-out containers and margarine tubs are great choices or cell packs you get from the garden centre. All containers need holes in the bottom for drainage. Plant containers for seedlings need to be very clean to avoid disease and should be disinfected by a teacher with a mild bleach solution before use. Peat pellets are the simplest growing medium but you can also plant the seeds in potting soil. 

Get the peat pellets 

When soaked in water, peat pellets grow to seven times their size and have nutrients that seeds need to grow. These pellets can be easily transplanted into larger pots or a garden when the seedlings are ready. You can purchase your peat pellets from Stokes Seeds or locally, such as at a dollar store.

You can also purchase a seedling tray for the peat pots with a clear plastic roof, creating an instant greenhouse (a seedling tray comes with the optional Stokes Seeds® Tomatosphere™ Starter Kit). Be careful not to allow excess moisture (humidity) in the tray, as it can lead to fungus growth. Simple daily ventilation of the "greenhouse" by taking off the lid will prevent this problem.

Find or set up appropriate growing conditions

You will need a place in your classroom/learning environment that provides the best available conditions for germination, and where all the planted seeds can remain throughout the inquiry.

Tomato seeds do not need light to germinate, however, if you are planning to use the seedlings for further inquiry, they will need to be placed near a window or a grow light for at least 8 hours a day.

Growing Tomato Plants

Seeds need a warm environment during the germination phase.  If the air outside the school is cold at night, do not leave the planted seeds along the windows unless protected from the cold. Newspaper between the windows and the plants will help.

Planting Reminder

Plant the seeds on a Wednesday or Thursday, and NOT before a holiday Monday.

Step 3

Introduce the program to the students

How you introduce Tomatosphere™ is up to you. The Introductory Learning Activity Suggestions in each of the Resources by Grade has age-appropriate suggestions and scenarios that can be used to initiate and engage students in the Seed Investigation.

Step 4

Plant the seeds with your students

  1. Soak the peat pellets in warm water for about 40 minutes, or until fully expanded, prior to planting.
  2. Put each peat pellet (or soil) into an individual planting container. Alternatively, you can use a seedling tray to hold the seeds and pellets (or soil).
  3. Label the planting containers accurately with the letter on the seed package.
  4. Individually, have each student press one seed into each peat pellet (or soil) to a depth that is about the same as the length of the seed (2-3 mm).

Ensure your labelling is accurate so that the seeds do not get mixed up. This is very important for accuracy of the final results.

Fair Test Alert

To ensure a fair test is conducted, make sure both groups of seeds are exposed to the same conditions (i.e., heat and water).

Step 5

Observe and record the seed germination

Seed Care and Watering

The peat pellets (or soil) should be kept moist during the germination phase. Check the peat pellet or soil daily to ensure that it is damp to the touch, but not soaking wet. Add water accordingly as needed. The watering schedule may vary depending on the humidity of the room.

Remember to water the peat pellets or soil before leaving for the weekend and as soon as possible upon return. It is important that the peat pellets or soil does not dry out.

Observing and Recording Results

Determine Germination

The primary objective of the Seed Investigation is to determine the number of seeds that germinate compared to the number planted for each of the two types of seeds (treated and untreated).

A seed can be considered to have successfully germinated when two (2) distinctly separate cotyledons (embryonic leaves) can be seen (image below).


Recording Results

Record how many seeds germinated each day for 2-3 weeks or until 5 days after the LAST seed germinates. See the example observation chart below. Use a plastic stir stick to mark when each seed has been recorded .

Summarize Results in a Chart


"A" seeds

"B" seeds

Number of seeds planted



Date of planting seeds



Date on which first seed germinated



Date on which last seed germinated (do not count seeds that did not germinate)



Total Number of seeds that germinated



Reveal of the Seed Identity

After submitting your results, you will receive an automatic response revealing the identity of the two types of seeds (i.e., control vs. treated).

Step 6

Submit the results online

When you submit your results, please make sure that you have the following information at hand:

  • Your username and password that you used when you registered.
  • The number of each type of seed planted and the number of each type of seed germinated. (Use the Results Summary to compile your results)
  • Results should be submitted as soon as possible after completing the investigation.

Submit Your Results

Celebrate Your Contribution

Certificate of Participation

After submission of your results you will receive a Certificate of Participation that you may print off for each of your students. The certificate is signed by former Canadian Space Agency astronaut, Dr. Robert Thirsk, and the principal investigator for the Tomatosphere™ project, Dr. Michael Dixon, University of Guelph.

Planning for Next Year

If you wish to receive Tomatosphere™ seeds again next year, remember to order seeds. You are NOT automatically signed up to receive seeds from year to year. You can also follow us on Twitter (@Tomatosphere).