1. Growing Plants 1
Growing Plants via Hydroponics
By
Sandra Cash & Hannah Peterson
Dr. Thomas
Crown College
General Biology, Section 112
30 April 2012

2. Growing Plants 2
Abstract
This article first defines hydroponics and relates the history of hydroponics. Secondly, this article
describes the various methods of hydroponics. Next, this article talks about a few of the problems
hydroponics has compared to problems with cultivation in soil. Then, it goes over Sandra Cash’s and
Hannah Peterson’s experiment to determine which method of growing plants is better, hydroponics or
soil. Lastly, it goes on to talk about the results Sandra Cash and Hannah Peterson found through their
experiment.

3. Growing Plants 3
Hydroponics is the method of growing non-aquatic plants, in a reservoir of water using a
nutrient solution that is added to the water to encourage plant growth. This is advantageous for growing
crops out of season in a green house. The hypothesis of this experiment was that plants would grow
better in hydroponics than in normal soil conditions because of the ability to control the amount of
nutrients the plants receive. According to the University of Arizona in a study of the growth of tomatoes
in hydroponics:
“The development of hydroponics has not been rapid. In the U.S., interest began to
develop in the possible use of complete nutrient solutions about 1925. [Because] Greenhouse
soils had to be replaced at frequent intervals or be maintained from year to year by adding large
quantities of commercial fertilizers. As a result of these difficulties, research workers in certain
U.S. agricultural experiment stations turned to nutrient solution culture methods as a means of
replacing the natural soil system with either an aerated nutrient solution or an artificial soil
composed of chemically inert aggregates moistened with nutrient solutions” (Hayden).
Hydroponics is a subset of hydro culture and is a method of growing non-aquatic plants, using
mineral nutrient solutions, in water, without soil. In certain situations it can be more effective to grow
plants in hydroponics then in regular soil because you can then control what kind and how much of the
nutrient solution to add to the water. The experiment was to discern whether Purple Daisies,
Osteospermum, would grow better in a hydroponics kit then in regular soil conditions. According to
studies completed by institutions such as the Delaware Valley College;
“Hydroponics is the scientific frontier of agriculture, which sustains human life on Earth.
The challenge is to meet the world’s food needs while preserving Earth’s natural resources. At
the same time as we are concerned with hydroponic food production on Earth, the US National
Aeronautics and Space Administration is also committed to this new technology to cultivate

4. Growing Plants 4
crops in space, which is vital to human exploration of the Moon and Mars” ("Delaware valley
college," 2011).
Hydroponics is an alternative for plant growth, but it is not without its own drawbacks. With
hydroponics, there is the possibility that the plants can contract disease such as Pythium
aphanidermatum, a water mold that infects young plants and slowly kills them. It is increasingly difficult
for those that work in greenhouses, because it favors warm and damp conditions (Parker). Doctor
Timothy Shelford at Cornell University has studied some risks of growing plants in hydroponics:
“Pythium aphanidermatum has been identified as the main obstacle/risk in the
production of hydroponically grown baby leaf spinach. This organism is so prevalent that even
crops grown in fresh nutrient solution will often show signs of Pythium damage at harvest time”
(Shelford, 2010).
Before starting this experiment, the hypothesis was that the purple daisies would grow better
and faster in the hydroponics kit since it allowed for the control of nutrients and therefore control of the
growing conditions. Twelve individual daisies were grown, six in regular soil and six in the hydroponics
kit and all were monitored over two months.
A container holds about six gallons of water with two teaspoons of nutrient solution for every
gallon of water. Six plant containers are placed down in the nutrient solution. An aquarium air pump
constantly bubbles in the nutrient solution, keeping the plants’ roots from drowning. Clay pellets fill the
planters and allow the water to reach the plants without the plants being so deep in the planter so that
sunlight cannot reach them.
Aside from the planters, the rest of the container is covered to block the nutrient solution from
being exposed to sunlight; this is to ensure that algae does not begin to grow in the hydroponics kit.

5. Growing Plants 5
During the course of the experiment, seeds were first kept watered and under artificial lights to
stimulate growth, after the roots became large enough to support themselves all twelve plants were
moved into larger planters and the plants going into the hydroponics kit were totally removed from soil.
After one week in the new planters, the soil grown plants began to look healthier then the
hydroponics plants. After two more weeks the soil plants continued to look healthier than the
hydroponics plants, but watering for the soil plants was increased from 50 ml to 60 ml. After three
weeks, the soil plants continued to improve, though plants did not appear to be as large as they should.
The plants in the hydroponics kit still looked unhealthy, especially the three farthest from the sunlight.
The water in the hydroponics kit was quickly changed, and three teaspoons for every gallon of water
was added to the nutrient solution to encourage plant growth.
Two weeks later showed continued improvement with most of the soil plants, but three were
withered and dead looking. The water level in the hydroponics kit was low, so about 50 ml of water was
added directly to each plant. The three plants farthest from the sunlight were dead. These experiments
took place in the Chemistry lab in Crown College from February 21, through April 17, 2012.
Results of this experiment were inconclusive and more data is needed to make an informed
conclusion. Half of the hydroponics plants died due to the lack of sunlight, since the planters shaded
them. The three hydroponics plants that did survive grew extremely slow, to about one inch in length.
The soil plants did better, although half of them also died due to unknown reasons. The surviving soil
plants grew faster and developed multiple stems and leaves. The soil plants grew to about three to four
inches, and looked healthier than the plants in the hydroponics kit.

6. Growing Plants 6
The results of the experiment could have been affected by the two weeks needed for the hydroponics
kit to be shipped from the company, and another two weeks for the setup of the kit. All results were
based on a month given to the growth of the plants from the time available. Based on the results of this
one experiment it appears that hydroponics are not better for plant growth, but when data from other
existing experiments is added, the results are more in favor for hydroponics depending on the type of
plants grown.
Hydroponics is mostly used to grow crops such as lettuce, tomatoes, and other leafy green
plants (Schmidt). Flowering plants have been grown using hydroponics before, but it is much more
difficult and the time needed for growth is much longer. If the experiment is repeated it would be best
to try two or three species of plants for a variety and so that the results are not skewed in any way. It
would also be prudent to allow more time for plant growth or to use faster growing plants. Pre-grown
plants would be a way to examine whether or not hydroponics keeps the plants healthier than plants in
soil conditions. It would also improve results if an artificial lighting system was set up above the plants
so that the results are not based on a differing amount of light each plant receives.

7. Growing Plants 7
Another way that could be used to improve the results would be to use a different hydroponics
kit that would allow differences on how the water reservoir is used. There are five different types of
hydroponics kits available for commercial use at this time. According to professors at the University of
Illinois at Urbana-Champaign, there are four main systems that are effective for plant growth (Schmidt).
The first is the simplest and probably the most well know method known as the water culture,
reservoir method, and the aquaculture method. This method involves totally immersing the plant roots
in a nutrient solution mixed with a large amount of water.
Next is the Aggregate Culture method that has the plant roots buried in sand or gravel and a
supply of nutrients and water are added to the container when needed. This method is effective
because the sand/gravel support the roots. Aeroponics is another, more complicated way to grow
plants. This method has the roots totally exposed in an airtight container and constantly misted with a
nutrient/water solution.
Lastly, there is the continuous flow system, which has the roots planted plastic piping, such as
polyvinyl chloride (PVC) pipe, commonly used for household waste plumbing, to allow a steady stream
of nutrient/water solution to constantly flow over the roots. A water pump is connected to the pipe and
to a large water tank, this allows the nutrient/water solution to be recycled and reused.
In conclusion, hydroponics is a good alternative for soil grown plants when the hydroponics kit is
used correctly and plants receive regular water/nutrient solution. While there are risks, they are less
obvious and there is less worry about parasites and diseases then with soil grown plants. Also, it is
important that someone who is interested in growing plants in a hydroponics kit, research the
information very carefully and totally before buying a kit. It is also important to know what species of
plants grow best in hydroponics conditions, and how they will respond to the various nutrient solutions.

8. Growing Plants 8
References
Delaware valley college. (2011). Retrieved from
http://www.delval.edu/pages/nrbm/C1104/
Hayden, A. N. (n.d.). hydroponic tomatoes. Retrieved from
http://ag.arizona.edu/hydroponictomatoes/history.htm
Parker, K. (n.d.). Pythium aphanidermatum. Retrieved from
http://www.cals.ncsu.edu/course/pp728/Pythium/Pythium_aphanidermatum.html
Schmidt, J. (n.d.). Hydroponic systems. Retrieved from
http://www.aces.uiuc.edu/vista/html_pubs/hydro/hydroponic.html
Shelford, T. (2010). The risk of pythium aphanidermatum in hydroponic baby-leaf
spinach production. Retrieved from
https://ecommons.library.cornell.edu/bitstream/1813/17229/1/Shelford,
Timothy.pdf