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Can household compounds (e.g. tea) be used to promote good health in plants

Can household compounds (e.g. tea) be used to promote good health in plants

Introduction: (Initial Observation)

You drink half of your tea and empty your cup into the nearest flower pot. Is it good for plant? I have seen people pouring coffee, soda and even ice cream in flower pots. How do these substances affect the plant? Can plants consume and benefit from our food and drink leftovers? How about soaps, detergents, oils and other household compounds?

Plants need certain nutrients in order to grow healthy, can we find some of those nutrients in household substances?

In this project you will investigate the effect of household compounds on health and growth of certain plants.


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 the nutrients that plants need in order to grow and remain healthy. Read books, magazines or ask professionals who might know in order to learn about the effect of different substances on plants. Keep track of where you got your information from.

To find out what are the chemical substance in tea, search the Internet for “Tea Chemistry”. You may get a result like this:

A tea leaf contains traces of proteins and carbohydrates, amino acids and lipids, as well as vitamins (carotene, thiamin, riboflavin, nicotinic acid , pantothenic acid, ascorbic acid, B6), minerals (manganese, potassium), and antioxidants as we shall see. All of these in tandem, provide essential nutrients necessary for our diet. However, modern pharmacology is primarily concerned with medicinal properties of plant components. Most of this research centers on the antioxidative properties of tea constituents.

You can do similar tests for almost all other substances.

You may also search for “fertilizers” to find out what chemicals are considered a fertilizer and are good for plants.

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 find out if household substances can promote good health on plants. We will test tea, coffee, sugar, milk, soda and a liquid detergent.

You may change the material if you wish. I have seen some people test the effect of soda on plants that already contains sugar. So you may replace sugar by soda.

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 independent variable for our investigation is the type of substance that we test (tea, coffee, sugar, milk, soda and a liquid detergent).

Dependent variable is the physical conditions that represent the health of the plant such as color of leaves, size of leaves, rate of growth, and visually detectable symptoms of plant disease.

Controlled variables are light, soil, nutrients, temperature and any other environmental condition that may affect the plant health.


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:

I think organic material that can be decomposed will change to nutrients usable for plant, so milk, coffee, tea and sugar will promote good health on plant, however material such as detergent and oil are harmful to the plant.

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.”


This experiment consists of three steps.

  1. You grow some seedlings in small flower pots. You need to have 3 plants for each of the substances that you want to test. So for 6 substances for example you will need 18 plants. Also use 3 additional plants for control.
  2. When all plants are young, fresh and healthy, start to add the test substances to the plants. To do this, just use those substance in the liquid form to water the plants. Use the same concentration that you usually use at home. continue to add fresh water to the control plants.
  3. Make daily observation and record your results in a table. Each column represents one plant, each row indicates one date.


Following is a detail of the procedures:

Step 1:

Grow plants from seeds.

Why Grow from Seed?

The most obvious reason for growing plants from seed is the lower cost per plant. Another reason is that many varieties can only be started (or are easier to start) from seed.

Soaking the Seeds

Most seeds will benefit from being soaked in warm (even hot but never boiling) water. The addition of a small amount (1/2 teaspoon per pint of water) of saltpeter (sodium nitrate) to the water may help many varieties of seed with very hard seed coats. Soaking for a few hours up to as many as 48 hours in the case of seeds with very hard coats will speed up the germination process. After soaking, blot them a bit with paper towels and plant them in the growing medium immediately or before they have a chance to completely dry out again.

Containers for Germinating Seeds

Any kind of plastic container at least 3 to 3 1/2 inches deep will work. Used containers should be rinsed with a solution of about 1 part bleach to 9 or 10 parts water. Rinse and dry thoroughly before using. I have used the containers that supermarket delicatessens use for salads and pastries, etc. The only problem with them is that holes must be punched at the bottom for drainage. Then some kind of tray is needed below that to catch the overflow of water. The flats that are designed and manufactured specifically for germinating seeds seems to be the best solution over all. They are available with a variety of pocket inserts for various sizes of plants. It is possible to graduate from the smaller pocket inserts to larger ones as the plant begins to grow. They already have holes at the bottom that allow the excess water to drain into the tray in which they are snugly placed. The drainage of water is very important because soil that is too damp will either cause the seeds to rot or will allow the growth of mold, fungus and other diseases – one of the worst enemies of seeds trying to grow into seedlings. There are clear plastic lids that can be placed over these nursery flats to prevent drafts and to protect seeds from cold drafts. As the plants begin to grow these lids need to be set off center to allow air flow and finally removed completely to allow the young seedlings adequate air flow. These flats can be reused year after year as long as the 1 part bleach to 9 or 10 parts water solution is used to wash them and then allow them to dry just before reusing.

Growing/Germinating Media

Growing Media, or Germinating Media is plural for Growing Medium or Germinating Medium, This is the material in which the seed is placed to germinate and grow. Of the various growing media, you will need to select the medium that is best for your specific purpose. Listed here are some of the options that are widely available for the gardener.

Peat moss is made up of decomposed aquatic plants and can be very acidic. It retains water and may not allow for adequate aeration or drainage. For this reason it is frequently used with other substances but not by itself.

Sphagnum moss is made up of dried bog material. It is fairly sterile and because it is very lightweight it can absorb as much as twenty times its weight in water. Its value as a fertilizer is not very good, and its ability to absorb water evenly is not very desirable. It, like Peat moss, is a good addition to make up a growing medium but is not the best substance to use by itself.

Vermiculite is expanded mica. It can retain a large volume of water for long periods of time. Although it contains a high level of magnesium and potassium and can hold nutrients and is good for aeration, It is not used by itself but is yet another ingredient in a final mixture for germinating seeds.

Perlite is a volcanic ash. It holds water on its surface but does not allow much absorption. It has no elements needed for plant growth and does not hold nutrients well. It does promote good aeration , stays cool and is a very good ingredient as part of a growing medium.

Sand is a good choice for root cuttings but is a bit too heavy for germinating seeds, it does not hold water, nor nutrients and is not recommended for germinating seeds.

Rich garden soil is good for plants but it does not offer the conditions necessary for germinating seeds because it does not allow for proper aeration and drainage for seeds. It is not sterile but after sterilization (bake it in a pan at 180 degrees for 30 minutes) it can be used as an ingredient in a good growing medium.

Special mixtures prepared for germinating seeds are available at nurseries and garden centers. These are very good for starting your seeds. For a little less money you can prepare your own mixture. Mix 1/3 to 1/2 sphagnum or peat moss or any combination of both with 1/2 to 2/3 vermiculite or perlite or any combination of both will make a very good growing medium for germinating most any kind of seed. The ideal mixture would have about 50% solid material, 25% air space (oxygen) and 25% moisture.


It is generally more economical to germinate seeds during the warm months when the heat and light from the sun is free. Temperatures generally in the mid 70s up to 80 degrees f. are needed to germinate most seeds. Although there are seeds that require 70 degrees and lower. When temperatures inside drop below 70 degrees at night the germination of many kinds of seeds can be impeded or even halted. It is important to keep the seeds at a constant temperature and away from drafts such as too close to doors and windows. If they are growing near a window to take advantage of the light during the day, it is a good idea to move them farther back as the sun sets to avoid exposing them to drafts. The lack of constant heat is one of the main reasons that seeds fail to germinate.

When germinating seeds indoors during the winter or indoors in air conditioned environments it is important to keep the soil warm. There are several ways to accomplish this. In greenhouses heating coils can be used. For smaller batches of seeds in the typical home it is possible to set the seed flat upon blocks and put a 40 watt light bulb underneath the flat. 60 to 100 watts are likely to generate too much heat. The soil should feel warm, but not too warm. Care should be taken to avoid contact with flammable substances. A heating pad placed beneath the flat or seed containers can be used but care is needed for this too since the controls on some of these heating pads will allow too much heat. Again the soil should feel comfortably warm not too warm or hot.

Besides warm soil, the air in the room where most kinds of seeds are germinating will need to be at least in the 70s. The higher up you place the seed flats the warmer the air is likely to be in any room. Since heat rises, the top of a refrigerator would be warmer than on a table at waist level. If the room temperature is 70 or 72 degrees f. the difference of 2 or 3 feet of height where the same room may have temperatures from 74 to 78 degrees f. can make the difference in whether or not some kinds of seeds will germinate. Those that require lower temperatures should be placed at lower levels within the room.

Once the seedlings appear and begin growing into plants, the heat should be reduced to around 65 to 70 degrees f. during the day with temperature as low as 55 to 65 degrees f. at night. There are exceptions to this. Melons, cucumbers, eggplant, peppers, tomatoes, and nearly all tropicals will prefer 70 to 80 degrees f. during the day and 60 to 70 degrees f. during the night.


Light is not the same thing as heat. Although heat is generated by a light source such as the sun or artificial light, it does not continue generating heat when the lights are turned off or when the sun sets. The heat required to begin the germination process should remain constant, day and night, at least during the early stages. The light source may or may not remain constant, but will be necessary for long periods. Simulating the longer daylight hours of spring – 10 to 12 hours per day is best for most species. Those seeds that require constant light will need artificial light (fluorescent or grow lights are best) until germination occurs and possibly for some period of time afterwards. Seeds that require total darkness should be covered with black plastic until germination occurs. Once germination has occurred, all seedlings will need enough light for photosynthesis to enable them to develop into strong healthy plants. If seedlings are growing in overcast conditions of winter the continued use of artificial lights will be required.


Before sowing seeds in the growing/germinating medium water it thoroughly and let it drain off. Sow seeds and cover with plastic, glass, or with the specially designed clear plastic covers that can be purchased with the nursery flats. These seeds will probably not need to have anymore water nor mist added until after germination occurs but it is still a good idea to check the top of the growing medium daily to be sure. Too much water (inadequate drainage) will cause seed rot, mold, or fungus. Check the growing medium every morning. When the top layer feels a bit dry it can be misted. Watering from the usual containers can disturb the seeds. It is best to sprinkle lightly or better yet, use a spray bottle with a mist attachment. This fine spray will lay down a nice amount of moisture and will not cause gullies or pockets to disturb the seeds. Water is best at room temperature or even a bit warmer – never use hot water nor water that is too cold such as cold water right from the tap. The best time to water is in the morning. Do not allow the growing medium to dry out and do not water so much that is remains soggy or wet. Always water from the top (a mister is best) rather than rely on adequate moisture to soak up from the bottom of the tray. The growing medium needs to be watered from the top down to assure an even distribution of moisture throughout. too much moisture remaining at the bottom of the tray will cause problems associated with inadequate drainage and the layer at the top may remain too dry.


The first growth to appear on the seedlings are the cotyledons. These are not true leaves but are food storage cells. This food will only last the seedling a short time and it will be necessary to begin feeding the young plants just as soon as the first true leaves begin to appear, usually within a couple of weeks. Purchase a good quality all purpose water soluble plant food such as Miracle-Gro. Always read the label. When fertilizing young seedlings, start out with a mixture that is about 1/4 the strength that is recommended for mature plants. Use this solution about once a week. Gradually increase the ratio as the plant grows and becomes stronger. After several weeks and the plant seems strong and healthy increase the mixture of plant food to water to the full strength as recommended on the label. Do not believe, in the case of plant food or fertilizer, that “more is better”. The manufacturers test their products and know what formulae is best. Follow the instructions on the label.

What type of seeds and how many?

You can plant any type of seed that you like. Just consult the seller and make sure that they will germinate fast. If you are not sure, just use beans (any type you like) as seed. Plant 3 seeds in each pot. The reason that you plant 3 in each pot is that some seeds may fail to germinate. You will need at least one germinated seed in each pot. Simply use a pencil to make a 1″ deep hole, place a bean seed in the hole and cover it.

Another method for growing beans is keeping the seeds out of soil or medium until they germinate.

First start the seeds off into growth by chitting them. Chitting overcomes the problem of seeds rotting before they germinate. Chitting, shown in steps 1 to 6 below, is carried out using a plastic food container like those used for sandwiches or the freezer.

1. Line plastic food box with absorbent paper.
2. Spray the paper so that it is thoroughly moist.
3. Place the beans about 1in. apart to give room for the roots to grow.

Lay a water retentive liner such as a folded paper kitchen towel in the base of the box. Spray the paper towel evenly with water to ensure that it is thoroughly moist all over. Pour away any excess water. Place the bean seeds evenly over the damp towel, about an inch or so apart, to allow for as little root disturbance as possible when the roots grow.

4. Label the lid and put it on the box.
5. Leave the box in a warm place such as an airing cupboard.
6. Inspect the seeds daily.When they have germinated with 1in. long roots they can be potted up.

Put the lid on the box. Label the box, most important if your are growing different varieties or other types of seed as well. Place the box in a warm place such as the airing cupboard or sunny window ledge.

7. Fill a pot with compost and insert sprouted seed.
8. When the runner bean plants are this size harden them off in a cold frame.
9. Plants should be hardened off in a cold frame for 2 weeks.

After the first week inspect the seed boxes carefully each day to check on germination. After the seeds have germinated and their roots are an inch long they can be planted into pots. Fill a 3 and a half inch pot with Potting Compost. Make a generous sized hole in the center of the pot so that the seed can be just laid into it with the root pointing down, but without dibbing the root down into the compost and bruising it in anyway. Fill the surrounding area of the hole with compost to within half an inch from the top of the pot to leave room for watering.

Water the pots to ensure the compost is moist but not saturated. Then place the pots in a warm position where there is plenty of light, for example in a cold frame, greenhouse or on a sunny window ledge. Check regularly that the pots are not showing signs of drying out, watering when necessary.

Step 2:

Using household compounds to water the plants.

Prepare your household compounds with the concentration that it may be disposed. For coffee, milk, soda, tea and other liquid drinks, use them with the same concentration that you normally drink. For detergents, dilute it to the highest concentration that it may be after use. Like when you use a bottle of water and soap to wash your hand in the backyard. If you are planning to include lemon juice, vinegar or wine, use them with the concentration that they come.

Starting a certain date, when your young plants are all ready, label each 3 pots wit the name of household liquid that you are going to test on those pots and water the plants with that liquid instead of tap water. Three control pots will continue to get watered with regular tap water.

Step 3:

Observation and recording

In your daily observations you may measure the plant height (without stretching the plant) and condition of leaves. Record color change and withering in leaves. Use a table like this to record your results.

Average plant height after using household substances to water the plants

Date: tea coffee soda water/control
Nov. 22
Nov. 23
Nov. 24
Nov. 25

The number of days and the number and the name of substances that you test may vary.

Leaves condition after using household compounds to water plants.

Date: tea coffee soda water/control
Nov. 22 good, fresh
Nov. 23
Nov. 24 10% brown
Nov. 25 20% withered

You will fill up all the cells in the tables. What I have entered above are just samples of what you may enter in each cell.

Materials and Equipment:

List of material can be extracted from the experiment section.

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 is 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.


Since you are using 3 plants for each substance, you may need to calculate the average of conditions in each group. For example if you are measuring plant height as one of the effects, you will need to calculate the average plant height among the three samples that used the same liquid.

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.


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