For more back ground on hydroponics, I suggest you look at a couple of
earlier questions sent into MadSci Network. One is a
general overview. The oth
er has some good links.
Now, your question. Yes, you can build a small hydroponics system. In
fact, you might be surprised at how easy it is and how available the
materials are. I am going to illustrate two different variations. These
instructions are off the top of my head. I have illistrated, written
instructions burried in a file somewhere, but this will have to do for
now.
Supplies you will need for the canning jar system:
1. A number of canning jars (glass is better than metal because of the
possibility of metal toxicity) The size of jar you use will depend on the
size of the plant you want to grow and how long you are going to grow
it
2. Enough aluminum foil to entirely cover the outside of each jar
3. An air pump for a fish tank
4. Enough plastic tubing, elbows, etc. to get one air line into each
jar
5. A lid and ring for each jar (and maybe a few extra, just in case)
6. Some foam plugs (2-4 cm across)
7. Hydroponic nutrient solution
8. pH test strips and adjustment solution (The same stuff used for fish
tanks should work)
9. A sunny place to set up the system or additional grow lights
10. Seedlings to put in the system
1) The first thing is to get the seeds started. It is not easy to start
seeds in a hydroponic system. I would suggest that you start your seeds in
a starter tray or other small container. Use vermiculite or perlite as a
growing medium. They will be easier to wash off of the roots than regular
potting soil when the time comes to transplant the seedlings.
2) First, wrap each jar all the way to the top with foil. This will keep
light away from the nutrient solution and prevent algae growth. The foil
can be removed for short periods to look at the roots.
3) Next, punch two holes in each lid. The first should be 2-4 cm across
(or what ever size is needed to hold the foam plugs) and centered in the
lid. The second should be large enough so that the plastic tube will fit
snugly.
4) Fill the jars with nutrient solution. Leave about 2 cm to the top
of the jar. A concentrated solution can be purchased from mail order
companies and some garden centers. Just a note, regular plant fertilizers
do not contain everything the plants need to grow in hydroponics.
5) Set up the air system so that each jar has a line running through the
lid and into the solution. The line should be long enough to reach the
bottom of the jar. Turn on the air carefully. The air flow should be a
gentile bubbling. If it looks like the solution is boiling, you will need
to find some way to turn down or clamp off some of the air flow. (I think
I remember seeing pressure regulators for aquarium air pumps, but I'm not
sure.)
6) Remove the seedlings from the growing media and carefully rinse the
media from the roots. It is important to disturb the roots as little as
possible. Next, cut a slit halfway through the foam plug so that you can
gently center the stem of the seedling into it. Carefully handling the
plants and plugs, place them into the holes in the center of the lid. The
roots should be some what submerged into the solution. It is not necessary
for all of the roots to be in the solution.
7) Maintaining the system - Add nutrient solution to the jars as needed.
As the plants grow, they will take more solution. Also, check the solution
pH once in a while. The solution should be between 5.5 and 6.5. A
complete change of solution every couple of weeks might not be a bad idea,
either. This system will require daily maintenance.
The second system is just a variation of the first. Use a 10 - 20 gallon
fish tank with a piece of Styrofoam board on the top instead of the jars
and lids. You can put 8 to 12 plants in a single tank and the air system
is much simpler to set up.
One last thing. I will caution you about the choice of carrots as the
plant to grow hydroponically. For some reason, carrots don't normally form
the enlarged tap root in hydroponics. Beans work really well.
I wish you luck with the experiment. If you have any questions please feel
free to e-mail me. Thanks for the question!
Eric J. Biddinger
Grad Student - Department of Horticulture
Penn State University ejb190@psu.edu