Gardening Science Projects Archive

  • How Plants Cool Down Houses

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    During hot weather, there is nothing better than to have a cool house to serve as your oasis. Aside from your air conditioning, plants can also contribute to making your home cooler.

    How do they do this?

    You’re about to find out!

    What you need:
    • A reflector lamp or the sun (the lamp should have a 100-watt incandescent bulb)
    • 2 shoe boxes or cardboard boxes
    • Different types of plants in their pots (ask your parents or grandparents if you can use their plants)
    • 2 functional thermometers (digital would be best)
    • 1 small can of dark colored paint
    • 1 small can of white paint

    What you do:
    There are a few steps you need to do in this experiment:

    Step I:
    1. Get your boxes and place them at an equal distance from the lamp for equal lighting.
    2. Place the thermometers inside your boxes.
    3. Position your plants between the lamp and one of the boxes, so that they cast a shadow over the boxes.
    4. Turn your lamp on.
    5. Measure the temperature of the air after a while. Which of the two boxes has a raised temperature? Find out if the temperatures change.

    Do you think the number of plants make a difference?

    Step 2:
    1. Paint one box black and one box white.
    2. Place them at an equal distance from the lamp for equal lighting.
    3. Place the thermometers inside your boxes.
    4. Position your plants between the lamp and one of your boxes, so that they cast a shadow over the box.
    5. Turn your lamp on.
    6. Measure the temperature of the air after a while. Which of the two boxes has a more elevated temperature? Find out if the temperatures differ. Do you think the number of plants that give shade to the boxes make a difference?

    Step 3:
    1. Place the plants between the lamp and one of the boxes, so that the plants cast a shadow that covers most of the box.
    2. Turn on your lamp.
    3. Be sure to measure the air temperature in each box over time. Which of the boxes has a more elevated temperature? Does the temperature fluctuate? Remove or add plants. You can even change the box they cover. Which box maintains the lowest temperature?

    What you discover
    During the summer, plants shield the interior of our homes from sunlight, making our homes a lot cooler. Trees give shade to a home with its branches and leaves. This decreases the sunlight that strikes the house, lowering its temperature. During winter, trees and smaller plants shed their leaves to allow more sunlight to enter the home, raising the temperature inside it.

    The color of your walls and roofing also affect your home’s temperature. Light colors make sunlight bounce off. These are ideal paint colors during the summer. Dark colors absorb sunlight. These colors are for winter.

  • Beneficial Insects For Your Garden

    Borage Plant in Bloom

    Beneficial Insects For Your Garden

    The amount of time spent on this project can vary. If you choose to plant your plants from seeds, it will take longer before you can actually begin your project unless you watch from the time your plants sprout. You can also choose to get plants that are already grown and simply transplant them into the garden that you’re watching. The idea here is to attract certain types of insects to your garden that are beneficial to the entire garden.

    Question: When you plant specific plants in your garden, does it increase the number of beneficial insects? Are there certain plants that attract these insects?


    • Insect ID book
    • Tape measure
    • Borage plants – 5
    • Notebook and pen
    • Timer or watch


    1. Bugs love flowers. Flowers attract insects and many times those insects are beneficial to the garden. Some insects, such as bees, help pollinate crops. Other insects will eat the insects that are trying to eat your crops. So, which insects are good and which ones are bad?
    2. If you place certain plants in your garden, will it increase the good insects? Begin by creating your hypothesis and tell us what you think will happen.
    3. You will want to do this experiment during the spring, summer or early fall. Basically when there are plenty of insects around.
    4. You should begin before adding your plants to the garden. Sit outside and pay attention to what insects are frequenting your garden already. Take note of the species and what they’re doing. You need to identify them and write them down in your notebook. If you have trouble, this is where your insect identification book will come in handy.
    5. Mark off a small section of the garden and do a timed experiment. In a 3’x3′ area on a sunny day, take about 30 minutes to seriously observe what insects enter your sectioned off area. Make sure that you note the time in your notebook because you’ll be doing this again on another day and will want to watch at the same time of day.
    6. Write down the number of insects that you see in that 30 minute period. What type and how many of those insects are in your area? Document it.
    7. Once you’re done doing the timed experiment, plant your borage in that sectioned off area. In this experiment, we are going to plant 5 borage plants that are already in bloom to save time. Make sure that you water them and then leave them alone to adjust to their new environment. This will take about 3 days.
    8. Wait for a day that is as sunny as the first day that you went out to observe. Count the number of insects that enter the plot area beginning at the same time that you observed last time. So if you observed from 12pm to 12:30pm, make sure that you observe at the same time this time too. Are there more insects? Are there less? What kinds of insects are there? Are there any new ones?

    End result:

    The plants that you placed into your garden should have attracted more beneficial insects. Beneficial insects are vital to a well-tended garden. We may water and use plant food, but beneficial insects help to keep the garden healthy by eating the bad insects that will destroy your plants. Some of these insects also help the soil in your garden.

    For example:

    If your garden is full of aphids, you will want to lure more ladybugs into your garden because ladybugs eat aphids. This action will help to bring balance to your garden. Anything that helps to pollinate your flowers is also a beneficial insect. This doesn’t mean that it has to be bees.

  • Which is Faster – Hydroponic or Traditional Farming?

    Growing Strawberries Traditionally




    Growing Strawberries Hydroponically

    During this project, you are going to discover whether hydroponic farming (as seen to the left) is faster than traditional methods using soil (in the above photo).


    You may think you already know the answer to this question but you may be surprised by what you find.






    Experiment Length: 3-6 weeks


    • Two standard pots used for planting
    • Bean plant seeds
    • One bag of potting soil
    • 2-4 gallons of distilled water
    • Two peat pellets
    • Two potting nets for hydroponic growing
    • Ruler
    • Notebook/journal
      (Note : both peat pellets and potting nets should be available at a good local gardening shop and are both quite cheap.  A google search on “peat pellets” or “hydroponic potting nets” will also give many examples of where you can get them)


    Prepare two of your pots with the potting soil. Plant your bean seeds approximately ¼ to ½ inch below the surface of the soil. You will want to give the plants plenty of sunlight and water. For the best outcome, make sure to keep your plants in the same place throughout the experiment. Moving the plants from one area to another will create inconsistencies and contaminate your results.

    Prepare your hydroponic seeds by placing the seeds in a peat pellet and saturating them with water.  This will cause them to “puff up”.  Make sure the seeds are covered by a little bit of the peat before you “plant” them.

    Fill the other two pots with distilled water. Place the hydroponic potting nets over the top of the pot (making sure the water touches the netting). Place the peat pellets (with the seeds inside) on the nets.

    Water your soil plants every three to four days, or whenever the soil feels dry. With your hydroponic plants, sprinkle a little water on top of them to prevent the peat pellet from drying out. You will notice as the roots of the plants grown they will drape down into the water. Once this happens sprinkling the peat pellets may be discontinued if you keep the pots full of water.

    Now it is time to analyze, and observe. See which plants are growing the fastest. Use the ruler to record the height of the plant as well as the date of all measurements.

    Finally, you can conclude, which plant grew the fastest, and which reached the greatest heights. Which method do you think would be the best for growing plants.

    If gardening projects or experiments are right up your alley, we’ve got a few more to help you to get growing.  How about  the Seed Germination Experiment?


    To see if strawberry plants (like in the main photo) grow faster or better with dirt or hydroponically, you can set up a similar experiment with actual plants.  Set up the test conditions just like you did above with seeds, except this time, you already have roots.  Once they grow, here’s a great site with great recipes on how to eat them!  (They also have a pretty good section on how to grow them in your garden as well).


    As a final note, these will help extend the project:





  • Using Plants to Demonstrate the Effects of Pollution

    Plastic Bottle Pollution


    Idea Behind the Experiment

    Pollution is a very serious problem in the world we live in today. The problem is that often times the pollution present in lakes and streams is not visible to the naked eye. This experiment focuses on using the plant life present to determine the water quality of any body of water. Most if not all plants livinge in water are very sensitive to contaminants in that water. While they use the natural waste of fish and animals as a food source, any outside contaminants are likely to make the plants die or at the very least decrease their health.
    What you Will Need

    • Water plants such as Anacharis (a common aquarium plant) or Duckweed (which can be found in any pond or lake). But any water plant that can be found at the local home and garden store should work out well.
    • 3-4 containers such as small plastic aquariums or Tupperware bowls, or if you have a larger amount of space available, you can could use larger containers such as totes.
    • Pollutants (it is recommended that you choose products that are not visible in the water to prove the point). This can be anything from soap to automotive fluids, it can also include solid things such as shards of metal.


    1. Acquire the plants you plan on using (again check your local garden center or pet store both should have water plants that will work well)
    2. Fill your containers with water (make sure it is distilled, tap water will not work because of the chemicals present that will contaminate the experiment)
    3. Dissolve your pollutants in all but one of your containers (make sure you use a different pollutant in each container). This will show how different pollutants are more harmful than others.

    4. Place your plants in the containers.
    5. Put the containers somewhere they will not be contaminated but have access to the sun for at least half the day.
    6. This experiment should last 2-4 weeks.

    Over the following days and weeks, you are going to want to document what happens with each plant. Take pictures and very detailed notes on a daily basis. Be sure to note things like coloration of the plant, any wilting or withering as well as the appearance of the water that the plants are in. This will allow you to build up a timeline, this will give you a frame of reference for your report on how different types of pollutants effect the quality of the water.

    What to Expect

    You should expect to see some very drastic differences between the plants that are in clean water and the ones that have been exposed to pollutants. The ones exposed to the pollutants are likely going to die eventually but the process that they undergo is going to vary greatly. In some you may notice color changes, stunted growth or decay before the plant finally dies. This should be well documented both by observation and phot records.



  • Make a Home Made Terrarium or a Rainforest Habitat

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    A terrarium is used to simulate a rainforest-like effect by containing the moisture inside of an object and maintaining a suitable habitat for plants and animals. You will want to choose small plants and/or animals that prefer shade and are water loving and do well in the humidity.

    Some plants to consider are the venus fly-trap, moss, ferns, ivy, violets, and orchids. You can make a terrarium out of nearly anything that will allow you to form humidity to build up condensation. It really just depends on how big you want your plants. If you want to have bigger plants, you need to have a bigger container. In this design, you’ll be shown how to make a terrarium out of a glass jar but you can make a terrarium out of much larger items.


    In our test terrarium we’ve set up a humidity monitor and incorporated animals that are native to the rainforest habitat– a Chinese Water Dragon and tree frogs. To make a miniature rainforest:

    You will need:

    1 glass jar and lid or cork stopper (Any size – Bulk food jars are great)

    1 small bag of activated charcoal, which can be purchased at a local pet supply store

    1 small bag of soil (dirt)

    1 small bag of fish tank rocks (or small pebbles found outside)

    Choose a few plants (such as a small fern and a small African violet.)

    Peat Moss or dark potting soil


    Step 1: Make sure your jar is very clean. Fill 1/5th of the jar with your small pebbles.

    Step 2: Add a thin layer of the activated charcoal to the top of the pebbles. (The charcoal will help filter impurities from your plants water source.)

    Step 3: Cover the charcoal with a 1/2 inch layer of peat moss.

    Step 4: Now add a 1/2 inch layer of your soil over the peat moss. (If the root system of your plant is longer, add a bit more soil if need be.)

    Step 5: Plant your fern and violet in the dirt. Tip: If your hand can’t fit into the jar, try using small tongs, chopsticks, or even a fork to dig out a small hole and to help lower the plant into place.

    Step 6: Lightly water the soil until it’s moist and then place the lid on the jar. Place your terrarium in a spot where it will get plenty of sunlight, but do not place it in direct sunlight.


    Do not overwater your terrarium.
    If it seems dry you may mist it lightly with a spray bottle. Using a humidity gauge you can judge how humid the atmosphere is inside your terrarium. Keep the heat fairly high, ranging from 80-95 degrees.

    If it’s too wet inside the terrarium, you run the risk of mold growing inside and killing your plants. After a short while, you should see condensation build up and this is what your plants will use to survive. Very rarely will you need to water the plants inside the terrarium.

    If there are animals in your terrarium bear in mind that you will need to screen the top and spray it regularly to keep the humidity high as well as give them good air to breath.

    See how long it takes to build up the humidity so that it actually rains inside your terrarium. Test and keep track of how well the plants do and how quickly they grow as well as whether or not they prosper.  Determine which plants grow best in this type of environment.