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Growing Seeds Experiment

Updated: Aug 11

Science Experiment of the Month- May 2025


Growing seeds offers lots of ways to experiment! Let's investigate some of the most common and follow the directions for one.

6 of the same flashlight with 6 different batteries shown
Seeds are starting to sprout


Foster Curiosity

The first step in any science experiment is the hook. What about this topic makes you say something along the lines of "What??" "Why would this do that?" "I wonder what would happen if I do this..."


Check out this kid's article about how seeds grow.


Watch some of these videos about Seeds to see how they become plants







Form a Question

What about seeds growing has you curious?

Example Questions

  • What seeds sprout the fastest?

  • Can a seed grow in the dark?


How to form your own question

Measurables

In this experiment, there are many things you can choose to measure.

Time

Over the course of days or weeks, you can measure how plant sizes compare over time.

Water

Do plants need water to grow? You can measure the amount of water or other liquid you give a plant.

Growth rate

As the plant grows, you can measure the height, width, number of flowers, number of leaves, or even the number of stems it produces as time goes on.


Note: There are other things you can change, but that isn't necessarily what you measure. For example, you can change whether a plant grows in different brands of soil to see how the soil affects the plant growth. In this example, you are measuring the growth rate of the plant or time to see how many days it takes to sprout. Changes can be the measurable, but is often the variable instead.



How to Measure Time

For a multi-day project like this, an easy way to check your plants once a day, every day at the same time. What that looks like might be checking you plants every day at 3pm for 14 days or until the last plant sprouts.


How to measure water

Always stay consistent on the amount of water the plant gets, measure it out so everyone gets the same amount. If you are measuring the amount of water a plant needs, and each plant gets a different amount, just make sure to be consistent on how much each one gets. Measuring cups are a helpful way to keep track, but you can also measure in ML.


How to measure growth rate

Decide what you want to measure. If it is the amount of flowers the plant grows over time, that is a longer project than the plant that grows the tallest in 2 weeks. If you are measuring plant height or width, you should measure that every day or every other day during the project. For things like flowers, leaves, or the number of stems (if it is a plant that creates multiple stems such as a Cosmo) you can measure these every 3-4 days.


Variables

A variable is the part of the science experiment we are changing.


Note: A well-designed science experiment should have 1 variable. Once more than one thing is changed in an experiment, it becomes unknown what exactly caused the difference.


Example: A common thing to do in this experiment is take 3 plants and "test" whether they need water, soil, and sun. Say you put 1 plant in the dark, never water another, and grow one in a paper towel instead of soil. Did the plant in the towel grow faster than the other two because towels are a good thing to plant plants in, because it got more sunlight than plants that grow in soil, or because soil is just less important than the amount of sunlight or water? There are too many possible conclusions you could draw because you tested too many variables. It is important to pick 1 variable and test that one to come to a definitive answer. If you want to know how important soil is to a plant, change just what the plants grow in: put plants in 3 different types of soil, one in paper, one in rocks, and another in an empty container. The conclusion will be more definitive with 1 variable.


In this experiment, there are many types of variables to choose from.

  1. Types of seeds

    1. You can compare which ones grow faster, taller, smaller, more flowers, etc.

    2. If seeds are larger, do they grow faster?

    3. Sunflowers are all the same type of flower, but there are different types of sunflowers, how different are they really?

    4. Do some seeds make flowers before others if planted at the same time?

  2. Brands of seeds

    1. If you buy the same type of flower from 3 different brands, does it make a difference?

  3. Basic Needs

    1. Water

      1. How much water do seeds really need?

      2. Can I grow plants in stuff that is not water? Like coke or gatorade?

    2. Soil

      1. Do different brands of soil really make better plants?

      2. Can plants grow in stuff that is not soil? Like rocks, bark, paper?

    3. Sun

      1. What happens to plants that require full sun if I plant them in other places?

      2. How much sunlight do plants need to grow?

      3. Does morning sun vs afternoon sun make a difference for plant growth?

      4. Are all growth lights just as good as real sunlight?



-What About Seeds Growing Has You Curious?-



Forming your question

Now that you have thought about what you are curious about, think about how you want to measure the difference. As you can see, depending on what you want to test, your question can sound very different! And don't be limited by our question suggestions, you can form your own questions from what we started here.


Take the curiosity and form it into a question to investigate!



Make a Hypothesis

Now that you have created your questions, what do you think will happen?


Note: remember hypotheses are never right or wrong they are an informed guess. You should be able to give your hypotheses and explain to someone with a sentence why you think that. That reasoning can be as simple as I've seen it do that on our shelf.


Try this hypothesis-forming formula:

If_______, then_______

If I do this, then this will happen. This is a basic logic clause that is helpful to practice in science.


For example:

  • If I grow three seeds that are different sizes, then the largest seed will sprout first.

    • (Why do you think that? Because large seeds have more food inside to make the seed grow sooner.)

  • If I grow 4 basil plants from 4 different brands, then the most expensive one will grow the fastest.

    • (Why do you think that? Because more money means better.)

  • If I grow 3 plants in with different liquids, then the plant I give milk to will grow the tallest.

    • (Why do you think that? Because milk has vitamin D, which we get from the sun, which means the plant gets double the vitamin D so it will grow faster.)

  • If I grow plants in each room of my house, then the planting the kitchen will grow the most flowers.

    • (Why do you think that? Because the kitchen has more sunlight.)


*Note all bullets with ( ) are example thoughts are have not been proven true or false.


Still struggling to figure out how to form your own?

In this experiment, the first part should include what the variable is you are testing, followed by what you are measuring. This formula not only tells someone reading the hypothesis what exactly the variable is, but also what types of results they should expect to see. In the second example, you can tell the subject is basil plants, the variable is different brands, and time is being measured. Even if the hypothesis is wrong, we expect the results to be about different times the batteries lastest.


Give it a try!

And remember Science Fair Experiments give us a chance to practice real science. It's still practice, so it's okay to struggle. As you practice doing science fair experiments, you will improve.



Materials Needed

  • Seeds or seedlings of the chosen plant species

  • Plant pots or containers

  • Soil suitable for the plant species

  • Water

  • Light source

  • Measuring tools (ruler, measuring tape)

  • Labels for pots

  • Notebook for recording data


Methodology

  1. Preparing

    1. Choose the plant(s) you will be testing

    2. Pick the substrate and/or liquid you will br growing your plants with

    3. Decide where your plants will be growing

    4. After deciding the questions you want to answer, think about which materials you will be using and add them to this list above.

  2. Planting

    1. Plant all seeds in the same container with the same substrate and water, unless substrate or water is what you are testing.

    2. Put plants in their growing space where they can get sunlight, unless you are testing sunlight.

  3. Care

    1. Every other day, water the seedlings and check that they are still safe from critters.

  4. Collect data

    1. Every 2-4 days check on your plants to look for changes. After plants sprout, you can measure things like height, stems, leaves, and flowers.


Data Collection

Regularly measure and record plant growth, health, and any other relevant observations in your notebook. Pictures are a great way to capture the changes that happen over time.


Analysis

After conducting the tests, analyze the results to determine:

  • Which was the best or worst?

    • Whether you were testing soil types, different seeds, or something else, which worked best?

    • Was your hypothesis correct?

  • Was there any surprises that happened when growing the plants?

  • Optional: Cost-effectiveness was the most expensive plant/soil combination the best or did the cheaper alternative work better?


Conclusion

  • Summarize Findings

    • Provide a brief overview of the key results and whether they support or refute the initial hypothesis.

  • Discuss the implications of the findings for future research or practical applications in agriculture or gardening.

  • Recommendations

    • Suggest any improvements for future experiments or additional questions that arose from the study.

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