1059 Main Avenue, Clifton, NJ 07011

The most valuable resources for teachers and students

(973) 777 - 3113


1059 Main Avenue

Clifton, NJ 07011

07:30 - 19:00

Monday to Friday

123 456 789


Goldsmith Hall

New York, NY 90210

07:30 - 19:00

Monday to Friday

Use seedlings started from seed with three types of media or different rates of fertilizer

Use seedlings started from seed with three types of media or different rates of fertilizer

Introduction: (Initial Observation)

The amount of fertile land on the earth is limited and traditional farming methods can no longer produce enough food for the increasing population of the world. Hydroponics is a relatively new form of farming that eliminates our need for large amounts of land and fertile soil. In hydroponics, water delivers nutrients (fertilizers) to the plant.

As any other method of farming, hydroponics require some knowledge and skills that may be obtained by study, research or scientific experiments. In this project, I will study hydroponics and perform some experiments to answer my questions about this method of farming.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.  

Project advisor

Information Gathering:

Gather information about hydroponics. If soil is not involved, where do you place a seed or what will anchor plant roots? Find what nutrients are needed and the proper concentration for such nutrients. What prevents the roots from rotting? And what will be the mechanism of water distribution?

Information can be found in books related to hydroponics or on the Internet.

Keep track of where you got your information from.

Hydroponics comes from two Greek words “hydro” meaning “water” and “ponics” meaning “work”; in other words, water does the work of carrying the fertilizer.

Fertilizers that plants need to grow and produce fruit or seeds are usually called “nutrients” in hydroponics.

What is Hydroponics?

Hydroponics has been broadly defined as any kind of soilless plant culture, including growing plants in solution, sand, gravel, rockwool, perlite and other inert media.

Four main things are needed for a hydroponic system:

  1. plant container
  2. a reservoir
  3. a means for aeration
  4. a nutrient solution.

Plant containers can be in the form of pots or pipes.

The reservoir can be any water container. You may use a plastic or glass bottle as a reservoir. If the container walls are transparent to light, you need to cover them with aluminum foil or other opaque material to exclude light and prevent algae growth.

Aeration of the solution is most easily provided by gently bubbling air through the solution. Aquarium air pumps, plastic aquarium tubing, and aquarium valves work well. One small pump with enough valves can aerate ten or more hydroponic reservoirs.

Hydroponic companies sell salt mixtures that can be dissolved in water to make a hydroponic nutrient solution. House plant fertilizers, such as Miracle-Grow, will not work for hydroponics. You can also mix your own nutrient solutions but it requires about ten chemicals, balances, and lab glassware.

Many houseplants can grow well in a hydroponic solution. These plants include wandering jews, piggyback plant (Tolmiea menziesii), devil’s backbone (Kalanchoe daigremontiana) and spider plant. These four houseplants all root readily in solution culture reservoir. Lettuce is a good vegetable crop that is easily grown from a seed. Wisconsin fast plants are also easily grown from a seed. A variety of dwarf flowers can also be grown from seeds, such as coleus, French marigold, impatiens, zinnia, and polka dot plant. Even with hydroponics, give your plants adequate light and temperature if you want rapid growth. A fixture which holds two 4-foot fluorescent light bulbs, with two cool white tubes, work well.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

The purpose of this project is to learn some details about hydroponics by performing scientific experiments. Our main question for this project is:

How does our choice of nutrients affect the plant growth in a hydroponics system?

To be more specific, I want to know if I can use plain water or plain water mixed with regular fertilizers to grow plants in a hydroponic system.

Additional questions that can be the subject of this study are:

  1. Effects of solution aeration on plant growth.
  2. Effects of root pruning on plant growth.
  3. How does a plant affect the pH of nutrient solution?
  4. Effect of nutrient solution pH on plant growth.
  5. Examine mineral nutrient deficiency or toxicity symptoms.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

The manipulated variable is the type of water/nutrient solution. (I will try plain water, a commercial hydroponics solution and a solution of a commercial fertilizer such as Miracle-Grow.)

The responding variable is the growth of each plant after a certain period of time. (The time can be two weeks or 3 weeks. I will determine plant growth by the size of plants roots and shoots as well as the number of leaves and general condition of plant.)

Controlled variables are the temperature and light. (I make sure that all plants are in the same temperature and get the same amount of light.)

Constants are:

-the location of all plants
-the size of plant containers
-the type of plant ( Peperomia )
-amount of water
-Growing time for all plants (2 weeks for example)
-the type of plant container (Plastic cups)
-the size of plant containers


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Following is a sample hypothesis:

Plants with hydroponics solutions (nutrients) and plants with other fertilizer solutions will both grow well without any noticeable difference. The plant with plain water however will not grow well because of the lack of nutrients.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment: Comparing plant growth in hydroponics systems with different solutions.


In this experiment I will prepare three identical hydroponic systems and use them to grow three identical solutions. In one system I will use plain water. In the other I will use a commercial hydroponics solution and use it at the concentration suggested by the manufacturer. In the last one I will use a solution of a liquid fertilizer as suggested by the manufacturer.

Materials Required:

  • Sturdy polyethylene jug with screw cap
  • Planting container with holes in bottom
  • Perlite to fill container
  • Shallow tray sufficiently large to accommodate both jug and planting container
  • Pebbles to fill tray
  • Hydroponics nutrient solution
  • water
  • another liquid fertilizer

Horticultural perlite is readily available in almost any garden center or in the plant section of supermarkets.


Use the following procedures to assemble three identical hydroponics system, but use a different solution in each system.

Make a small hole in the bottom edge of the polyethylene jug as shown on the sketch. Fill the jug with your test solution. Replace the screw cap on the jug. Remember, your plant will be receiving nutrients on a continuous basis so the concentration should initially be very low. Plant a seedling in the perlite filled container and place the container in the tray. Cover the tray with pebbles to help retard evaporation of the water.

The capillary action of the perlite will draw water and nutrients up into the root zone and provide continuous feeding.


Variations on the experiment can involve the growing of different type plants and even the use of different size perlite (perlite is available in fine, medium and large size particles).

Materials and Equipment:

  • Sturdy polyethylene jug with screw cap
  • Planting container with holes in bottom
  • Perlite to fill container
  • Shallow tray sufficiently large to accommodate both jug and planting container
  • Pebbles to fill tray
  • Hydroponics nutrient solution
  • Water
  • Another liquid fertilizer

A Hoagland solution is a common hydroponics solution used by plant scientists. A cheaper alternative is to buy a premixed hydroponic fertilizer from a hydroponic supplier. There are dozens of hydroponic suppliers on the Internet. Homegrown Hydroponics sell DNF which costs $11 for 500 ml, which would make 50 liters of full strength nutrient solution. Fifty liters would be plenty for most hydroponic experiments and it is even often possible to use half-strength solutions.

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments are made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.



Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

Hydroponics is a word coined by Dr. William F. Gericke of the University of California at Davis. It comes from two Greek root words “hydro” meaning “water” and “ponics” meaning “work”; in other words, water does the work of carrying the fertilizer.
Just like us, plants are mostly made of water. Every single thing a plant consumes is either water soluble or else it is dissolved in the air. The fertilizers the plant uses to grow and produce fruit or seeds are usually called “nutrients” in hydroponics.

One note here–do not be scared off by the vocabulary used in hydroponics: there are a whole lot of 65 cent words used in this field. Sometimes the big words are good because they are precise; sometimes the big words are only used to justify the cost of a college education.

Here is the first concept to get a handle on:

There is no ONE, single way to grow plants hydroponically–there are many, many ways to grow plants right.

Indeed, in our experience, most people develop their own techniques and preferences. We find this totally cool since we live in America. There are some guidelines and “best practices” some of which are presented here, but have fun: plants are live and life can either be fun or a drag–it is up to you.

Here is the next concept:

It takes three full growth cycles to get the hang of this.

Hydroponics is incredibly productive. Typically your first crop is faster and bigger than anything you expect. By the time you finish your third crop, though, you look back at that first crop you thought was fantastic and wonder at how puny it seems now. Always donate your excess to a food bank.
Hydroponics is a developing field right now. The eventual end will occur sometime in this century when human starvation will be eliminated. Don’t get it wrong, though, people will still find things to fight over; but as long as there is freedom human starvation’s days are numbered.

Many people think that in hydroponics the plants are grown in water–like water lillies or other aquatic plants. This really does not hit the nail on the head. What gives the plants the accelerated growth rates is the extra AIR.
It may not sound right at first, but it is the abundance of Oxygen at the roots which give the plants the added boost we are looking for. For now, just trust us, it’s the Oxygen at the root zone which is the key. In fact, in still water, the roots can actually drown or “develop anaerobic bacteria” which is another way of saying “catchin’ rot”. Dropping a fish bubbler in the water is one way of aeriating the water since these anaerobic bacteria do not like air. (The prefix “an” on Greek root words usually means “not”.)

If Oxygen is the key, where does the water come in?

Good question. Water is the like a glue that holds all of life together. All the nutrients a plant consumes can be dissolved in water. There is a good reason for this: a plant has no heart, no bloodstream, no blood. The question now is,” How do the nutrients get from the roots all the way inside the plant to the leaves?” If we say “Sweat,” that wouldn’t be far off.

At the roots, the plant absorbs the water with the minerals dissolved in it. This nutrient rich water enters through tiny holes in the root hairs. This solution is passed up the tree from cell to cell until it reaches the leaves. At the leaves, the plant has more tiny holes. The plant spreads it leaves in the sunlight allowing the water to evaporate out the tiny holes in the leaf. Now here’s the important part: the minerals are left behind, up top of the plant.

Can you dig this? The nutrient solution you mix up is a lot like the plant’s own nutrient transport solution. It is like the sap the plant itself mixes up.

Q: What is the difference between Metal Halide Lights and High Pressure Sodium Lights?

A: Lighting technology is still changing and evolving. The two best ways to provide supplemental lighting to plants that anyone has come up with so far is to use bulbs made with either Metal Halide or Sodium inside the tube called High Intensity Discharge Lighting (HID).

Metal Halide shines with a blue tint, while High Pressure Sodium casts a more orange light. While both lights are very bright, Natural Sunlight is still the best quality light, and it is
free–the sun does not always shine where, when, and how long you might want. Increasing the length of the light cycle usually makes the plants grow faster.

Q: Why use one kind of light instead of the other?

A: Plants can be put into two categories:

Greening and Blooming.

Greening plants such as lettuce, basil, parsley, oregano, mesclun mix, etc. are grown for the green leaves themselves.
Metal Halide Light encourages larger leaves, more tightly spaced leaves, and is the preferred light for this type of plants.
Blooming plants such as ornamental flowers, tomatoes, peppers, cucumbers, pea pods, squash, watermelons, etc. are grown for the fruit of the blooms.
A typical technique is to use a Metal Halide Light on the young blooming plants to build a strong base for blooming, then to switch to a High Pressure Sodium Light at the Bloom stage. The light coloration (sometimes called frequencies) of the High Pressure Sodium Light causes most plants to bloom faster and with more blooms.

Q: Can I use a High Pressure Sodium Light all the way through on my Blooming, Fruiting plants?

A: America is a free country. You can do anything you can afford.

Q: What will the results be if a High Pressure Sodium Light is used from start to finish on Blooming Plants?

A: The coloration of a High Pressure Sodium Light is similar to Autumn sunlight, lower on the horizon. This often causes the plant to grow in a “hurry-up” form; the leaves are smaller, there is more spacing between the leaves, and the plant looks stretched. Sometimes this is a problem, sometimes it is not. If the High Pressure Sodium Light is shining along with Natural Sunlight, the effects are less pronounced. Just like everyone else who sells grow lights, we will always tell you to buy another one, but if one light is all you have and can afford just go with it, OK?

Q: What are Enhanced Spectrum Lights?

A: The High Intensity Discharge Light manufacturers have been responding to the needs of plant growers by coming out with new bulbs that shine the colors that plants use the most.

Early attempts used a High Pressure Sodium bulb that was modified with a little bit of blue light. These “Son Agro” bulbs were manufactured by Phillips. They worked especially well in greenhouses or supplementing Natural Light on Blooming plants. Now, in the 21st century, some Metal Halide Lights have been modified to provide a more complete light for plants. The best of these so far has been the “Clean-Ace” bulb developed in Japan especially for plants. The “Clean-Ace” Metal Halide bulb comes in 250 Watt size and 400 Watt size and will burn in any standard Metal Halide fixture of the same size. It costs more than a standard or Super Metal Halide Bulb, but can be a good compromise for those on a budget.

A large benefit of the Clean Ace bulb is that its color spectrum helps indoor plants stay compact with tight spaces between branches and leaves. This can be especially important if you are trying to grow tomato plants in a bush shape rather than as a vine. Often the varieties of plants which have a natural tendency to grow into a bush shape are called “determinate”; seeds which have a natural tendency to grow as vines are called “indeterminate”. The added blue light of the Clean Ace helps keep the bushes compact, especially when grown near a window.

Q: What else have you got?

A: Sunlight Supply has come out with a “Switchable Ballast”. It comes in two sizes 400 WATT and 1000 WATT. This jasper is the latest in technology and allows the ballast to run either a Metal Halide Lamp or a High Pressure Sodium Lamp by flipping a selector switch. One note here: if you buy this light system, you will need two separate bulbs. Make sure you check the fine print on other websites or stores to see if two bulbs will cost extra or if shipping will be an add-on as well as the price of the system itself. Look at your total cost, 3R Lighting gives you excellent value.