Science Fair: How Does Your Garden Grow?

Each year, families around the world spend lots of money buying just the right plants, just the right soil, and just the right fertilizer that they hope will make those plants grow in that soil. Gardening is a multi-billion-dollar-a-year business, so you would think they would have it all figured out by now. But in this experiment, you will have an opportunity to test out your own form of plant care—one that might revolutionize the industry.

Question: What do seeds like to drink?

Experiment Overview

In this experiment you will be growing seeds. That by itself isn't all that magical. But what makes this experiment unique is that you will be “watering” your seeds with more than just water. In fact, it is totally up to you to decide which liquids you will use to keep your seeds moist. You will probably want to include regular water for comparison, but you may find that your own special recipe, or something as common as what you have sitting in your refrigerator, on your dinner table, or in the glass in your hand, actually makes seeds grow better than water.

Did You Know?

In the United States, most beans can be planted and harvested within 90 to 120 days.

Michigan, North Dakota, Nebraska, and California are the leading bean-producing states.

Science Concept

Seeds need a lot of things to go right for them in order to grow. They need the right kind of soil, the right amount of light (or darkness), the right temperature, and of course, water. Water helps the seed gather nutrients from the soil, and helps those nutrients work through the growing seed. Fertilizers either deliver additional nutrients that the soil is not able to provide, or they help the seeds gather in the soil's nutrients in a more efficient manner. Some additives, such as chemicals or acids, get in the way of the nutrients the seed needs, and prevent the seed from growing. Others actually help this process along. Which of your liquid additives will do the most for your seeds?

Materials

  • 10–20 bean seeds

  • Several Styrofoam coffee cups

  • Potting soil

  • Measuring spoons

  • Marking pen

  • Ruler

  • A variety of liquids, possibly including the following:

-Tap water -Milk -Hot water -Fruit juice -Iced tea -Soda -Hot tea -Vinegar -Coffee -Cooking oil

Procedure

1. Fill each cup about ½ full with potting soil.

2. Place 2–3 seeds in each cup.

3. Cover seeds with another inch of potting soil.

4. Select a liquid and pour 1–3 tablespoons of that liquid into the cup.

5. Write the name of the liquid on the side of the cup.

6. Repeat steps 4 and 5 until all liquids have been assigned.

7. Place the cups in a safe, warm place where you can observe the seeds as they grow.

8. Once a day for the next two weeks (14 days), add another three tablespoons of each liquid to the proper cup.

9. Each time you add liquid, look for growth of the seeds in the cup. After two weeks, there should be measurable growth from many of the seeds that you can record with the ruler. Save these measurements in a data table for reference.

Questions for the Scientist

1. Which of your liquids produced the greatest growth in your seeds?

2. Did any of your liquids cause the seeds not to grow at all?

3. How did water do in comparison to the other liquids? Can you suggest a better alternative to tap water for growing seeds?

4. What ingredients did your test liquids have that might have caused the seeds to grow more slowly or not at all?

5. Can you think of any combinations of the liquids you tested that might work even better?

Conclusion

Acids, such as those found in vinegar or carbonated soda, tend to slow down the growth of seeds. Other liquids contain chemicals that either speed up or slow down plant growth. This experiment tested only a few types of liquids and only one kind of seed. You can extend this test to other seeds and other liquids. In fact, if you had enough time, you could track the growth of the seeds until they outgrow their cups. At that point, you could plant them outside and continue the test until they produce their crop. Testing ideas, discovering answers, and testing new ideas are what being a scientist is all about. It's not magic, it's science!

Science Quote

“Men love to wonder, and that is the seed of science.”

—Ralph Waldo Emerson, essayist

Science Online

Learn the basics of gardening, even if you have never put a seed in the ground, at The Garden Helper: www.thegardenhelper.com.

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