DP Tool Club 17/CD_ASCQ_17_101194.iso/vrac/hydropon.zip/HYDROPON.003

Text File | 1990-07-24 | 10KB | 160 lines

HYDROPONICS: GROWING PLANTS WITHOUT SOIL
by Dan Salzler

  Hydroponics is the process of growing plants without soil. It is not a new
idea and it really isn't difficult once the basic requirements are met.
There are two basic methods of hydroponics, one being the nutrient solution
method and the other being the sand or gravel method.
  All plants need certain elements to maintain growth and reach maturity.
In nature, these elements are supplied naturally or with minimum attention
by man. When plants grow hydroponically, all of the elements have to be
supplied and controlled by the grower. As a result, many technical problems
can arise making hydroponic gardening very labor intensive and quite costly
when done on a small scale. Nutrient deficiencies and toxicities show up
quickly, and often, unless carefully monitored. Yields are generally lower
than field grown crops and the flavor of the resulting fruit or vegetable
usually falls short of our expectations.
  By now, you may have decided that those vine-ripened tomatoes freshly
picked during a January blizzard are not for you. Certainly hydroponics is
not for everyone, but for those who have a green thumb or a curiosity that
won't allow the idea of picking fresh vine-ripened tomatoes to rest, it can
be a lot of fun. Hydroponics will provide a great education for children
learning about photosynthesis and plant growth, not to mention the
conversation piece when friends drop by. And those fresh foods!

Requirements for Plant Growth
  As mentioned earlier, growing plants hydroponically requires an artificial
supplement of all the elements needed to sustain plant life and growth.
  Water Plants are 80 to 90 percent water. This water provides support for
the plant as well as carrying dissolved nutrients to the necessary parts of
the plant for growth to occur. Plants use a lot of water and must have a
constant supply to maintain optimum growth.
  Nutrients All plants require mineral elements including nitrogen,
phosphorous, potassium, magnesium, calcium, sulfur, iron, manganese, boron,
copper, zinc and molybdenum. Carbon dioxide and oxygen are supplied by air
and water.
  Light For plants to grow, light is a necessity. Normal sunlight of at
least 8 to 10 hours a day is necessary to support growth and encourage flow-
ering.  Under artificial light conditions, the use of grow-lights or a blend
of incandescent and fluorescent light bulbs will provide enough light if
left on long enough to support plant growth. It is not necessary to keep the
growlights on 24 hours a day and, in fact, doing so will retard the
flowering process. Flowering is a function of the number of hours of
darkness, not the number of hours of sunlight. Simply remember to allow for
more hours of sunlight during the growing period, and when the plant is
large enough to support flowering, increase the number of hours of darkness
daily by turning off the lights earlier.
  Temperature Plants grow within a wide temperature range. Warm-season
plants, such as beans and tomatoes, do best with temperatures between 65 and
85 degrees F. Cool season plants, such as most herbs, root crops and members
of the cabbage family, grow best at temperatures about 10 degrees cooler.
  Oxygen Plant roots have to have oxygen to grow and to take up water and
nutrients. Soils generally contain enough oxygen, but roots grown in water
solutions have to have oxygen added.

Getting Started
  Preparing the Nutrient Solution The nutrient solution is the medium the
plant will be grown in; therefore, it must be complete with all of the
elements the plant needs to sustain optimum growth.
  Dissolve any 10-10-10 commercial fertilizer at a rate of one heaping
tablespoon per gallon of water. If you use the commercial granulated type, a
portion of the fertilizer will appear not to dissolve. This is the clay
particle the nutrient has been attached to, don't worry about it. To this
solution, add the minor element solution listed below.
  Minor Element Solution Mix 1/4 level teaspoons of boric acid and
approximately 1/10 teaspoon of manganese chloride in a quart of water. Use
1/2 cup of this solution for every ten gallons of nutrient solution used.
  Iron Mix 1/2 level teaspoon  of chelated iron (NaFe DTA) in a quart of
water. Use 1 3/5 cups per 10 gallons of nutrient solution. If chelated iron
is not available, use ferrous sulfate. Dissolve 1 teaspoon in a quart of
water and use 1 teaspoon of this solution per quart of nutrient solution.
  Checking the Acidity After mixing all of the minor elements and the
complete nutrient solution, combine to make a working solution. Before
placing the plant into the working solution, check the pH of the solution.
This will tell you if the solution is too acid or alkaline. the test can be
made by dipping a small piece of litmus paper, available at most drug
stores, into the working solution. You are seeking a pH of between 6.5 to
7.5
  If the working solution is too alkaline (pH is above 7), add a few drops
of dilute sulfuric acid per quart of solution. It the working solution is
too acid (pH is below 7), add a few drops of sodium hydroxide (NaOH). Use
care as these chemicals will burn clothes and skin.

Growing the Plant
  Nutrient Solution Method This method of hydroponics allows the plant roots
to grow in solution containing nutrients. A plant is suspended through the
top of a jar with the roots dangling freely in the solution and plant top
above the solution line. For growing one or two plants, use a jar with a
metal lid.  Cut a hole approximately two inches in diameter in the center of
the lid and place the plant through the hole. Support the plant by packing
cotton around the stem.
  Roots grow best in the dark, so paint the jar a dark color leaving a
narrow strip down the side of the jar so you can see the roots grow and can
determine the level of the nutrient solution. For larger plants, increased
support will be required as the plants get larger.
  Aeration As the plant grows, oxygen must be added to replace that which is
taken up by the plant. The easiest method is to bubble air through the
solution in use. An aquarium pump may be used with satisfactory results. If
this cannot be done, discard the old solution in the jar every two to three
days when the plant is small. Once the plant reaches a larger size, you will
have to replace the working solution every day.
  Changing the Solution If you use the pump procedure, you will have to
remove the working nutrient solution every 10 to 14 days. The actual rate of
changing will vary with the different size of the plant, temperature and
amount of light provided the plant.

Sand or Gravel Method
  This method of hydroponics involves the use of clean sand or washed
gravel, free of sand or silt. Growing plants in this manner is similar to a
field grown method except that the grower must control and supply all of the
elements for the plant growth.
  The container needed for this method can be of any size with the capacity
to retain the nutrient solution until flooding of the container is complete;
and then, to allow the solution to drain completely from the container from
the bottom.
  Place the seed or plant in the medium and then flood the medium with
nutrient solution 1 to 3 times a day or enough to keep the medium moist.
Allow the solution to completely drain through the medium each time. You may
reuse the nutrient solution over and over for 10 to 14 days. After the last
flooding of nutrient solution, flood the medium with clean water to flush
out accumulated minerals that can build up a toxicity level for the plant.
  Charting the Growth It is important to keep records of every flooding,
nutrient solution change and flushing. It is also important to keep track of
the length of daylight and hours of dark. You may want to grow miniature
flowers by shortening the day length and causing the plant to flower when it
is only a few inches tall.
Some nutrients deficiency symptoms you may want to watch for are:
  Nitrogen Small leaves turn light green or yellow; lower leaves lighter
color than the top; weak plant.
  Phosphorous Plants have dark green leaves; sometimes lower leaves become
purplish in color; lower leaves may become yellow between veins.
  Potassium Yellow spots develop between the veins on lower leaves;
yellowing or even dying of leaf margins develop on lower or old leaves.
  Calcium Tips of young leaves curl and die.
  Magnesium Leaf margins on lower leaves; lower leaves have yellow spots
with green veins.
  Sulfur Plants have light green leaves; leaf veins have lighter color than
the surrounding area; upper leaves are lighter in color than the bottom
leaves.
  Iron New upper leaves turn yellow; edge and tip of leaves may die.
  Manganese New upper leaves have yellow or dead spots; veins remain green.
  Boron New tip growth dies; plant becomes brittle.
----
  Reprinted, with permission of the author, from the Cattaraugus
Independent, Oct. 19, 1986. Dan Salzler is the owner of Herb Hollow Farm, a
retail herb nursery with many display gardens. It is located on Safford
Road, East Otto, New York.
------------------------------------

CLINTONIA
Magazine of The Niagara Frontier Botanical Society, Inc.
An Affiliate of the Buffalo Society of Natural Sciences
Vol. 2, Issue 1, January 4, 1987
* New Year Issue *
(Electronically Published Version: February 11, 1987)

Niagara Frontier Botanical Society, Inc.
Buffalo Museum of Science
Humboldt Parkway
Buffalo, NY 14211