We received this from Fred Bergman and are posting it here with
our thanks to him. We hope you'll find it useful!
From Seed Sowing, the easy way, 1996. Orchid Review, 104:23-25.
A note to me from Fred....
The best general purpose media I have found is Hill's Seed Sowing
Medium available from
G & S Laboratories
645 Stoddard Lane
Santa Barbara CA 93108.
An amateur bottle makes l Liter, costs $ 6.50pp. Ca residence add 7.75%.
Supplies are available from almost any chemical supply house, one being
the Aldrich Chemical Company Phone 1-800-558-9160, Fax 414-273-4979.
They accept credit cards. They have Erlenmeyer flasks, 500 ml, Z14,053-8
at 4.15 ea or 6/22.95; rubber stoppers, size 7, Z16,437-2, 20/16.75;
plastic sample vials with caps, 1.85 ml, Z13,618-2, 12/9.95; or glass vials
with caps, 2 ml, Z29,169-2, 100/29.00; and pH paper, Z11,181-3, 6.00/pkg.
Calcium hypochlorite can be obtained form a swimming pool supplier; copper
sulfate from a garden center, and demineralized water at almost any
supermarket. Desicant packets can usually be obtained at no charge from
your nearest pharmacy.Total cost about $70. I was off a little.
Tyndallization may be used to sterlize your media if a pressure cooker is
not available. However a pressure cooker is more convient and reliable.
Tyndallization consists of steaming 3 to 4 times at 24 hr intervals. Room
temperature is maintained between steaming intervals. Use a covered kettle
provided with a wire rack that suspends the flasks over the boiling water.
Boiling should continue until the contents reach the boiling point and is
maintained for a few miniutes.
SEED SOWING, THE EASY WAY
Many orchid enthusiasts have been told that the
germination of orchid seed requires special skills and
equipment. This is no longer true. Recent developments
have made it possible for anyone to successfully sow seed.
The only special equipment required is a large pressure
cooker normally used for canning.
During a study of seed disinfection, I discovered that it
is possible to add disinfection solution and seed directly
to the flasks. Good germination is obtained when the
following conditions are met; use only calcium
hypochlorite (CaHc), use CaHc at a very low concentration
and a low pH, and remove the CaHc solution from the flask
after the seeds have settled to the surface of the media.
I also found that flasks could be safely opened for seed
sowing by working under a cloth towel moistened with 10%
liquid bleach. These two techniques were combined and
tested repeatedly, producing viable cultures free from
contamination. The sowings were made in an area attached
to a greenhouse where plants and blooms are normally
packed for shipment. This area, far from a clean room,
demonstrated the effectiveness of this novel approach.
Over the years I have avoided reflasking, a task I do not
enjoy, by adopting the technique of sowing seed thinly and
restricting the loss of moisture from the media. This
approach makes it is possible to produce husky plants
without reflasking. By combining this novel seed sowing
technique and eliminating reflasking, it is possible to
sow seed successfully without the use of an enclosure or a
laminar-flow hood.
This paper provides a description of the entire seed
sowing procedure so that the novice will not have to
search the literature for supporting information. Many of
the required supplies are already available in your home.
The following is a list of the special supplies you will
need to acquire.
1-Calcium hypochlorite (CaHc)
2-Six 500 milliliter Erlenmeyer flasks
3-Six one-hole rubber stoppers to fit flask
4-Copper sulfate
5-pH meter or pH paper to cover the 5 to 6 range
6-Dehydrated orchid media for one liter of solution
7-Six small bottles with caps, 3-5 milliliter capacity
8-Three liters of demineralized water
Seed sowing starts with the proper harvesting of seed.
When a capsule starts to change color, began checking the
capsule on a daily basis. When a crack first appears,
remove the capsule and split the capsule lengthwise. Place
the capsule on a sheet of writing paper and cover the seed
and capsule with a second sheet of paper. After 24 hours
the seed can be shaken from the capsule. The seed, if
viable, will be free flowing and light yellow to brown in
color. After separating the seed from the capsule, store
the seed in a folded section of writing paper. If the seed
will not be sown for several weeks, place the seed packet
and a desiccant packet in a small closed container. Store
the container in the vegetable crisper of your
refrigerator. When you are ready to sow the seed, remove
the container from the refrigerator and allow it to warm
to room temperature before opening.
There are four operations that can be performed ahead of
time: (1) locate a jar with a plastic cap that holds about
250 milliliters (one half cup) and add about 30 grams
(2 tablespoons) of copper sulfate. Fill the jar almost
full with water and shake the solution occasionally until
all the copper sulfate has dissolved, (2) pack the hole in
each rubber stopper with adsorbent cotton, (3) cut twelve,
12 centimeter squares of aluminum foil, and (4) prepare a
stock solution of (CaHc).
You must determine how much CaHc powder will be required
to prepare the CaHc stock solution. This is done by
dividing 2.0 by the percent of available chlorine in the
CaHc. This will give you the number of grams of CaHc
required for 1 liter of stock solution containing 2000 ppm
as available chlorine (AC). For example, if the CaHc
contains 65% AC, (sometimes listed as the active
ingredient) divide 2.0 by 0.65 to find that 3.08 g of CaHc
should be dissolved in 1 liter of demineralized water. If
you prefer to use non metric units and/or you do not have
a sensitive balance, use the following procedure. The
weight of a level one quarter teaspoon of CaHc is close to
0.85 g. Multiply 0.85 by 1000 and divide by 3.08 (the
weight of CaHc determined following the above example).
The result is 276, which is the milliliters of water to be
used with one quarter teaspoon of CaHc to produce a 2000
ppm AC solution. Finally, divide 276 by 29 to find that
276 milliliters is equal to 9.5 fluid ounces. Using 29 in
the conversion of milliliters to fluid ounces produces a
solution within 5% of the desired concentration using
either British or US fluid ounces. Preparation of the
solution consists of measuring the water, adding the CaHc,
and stirring for several minutes. Allow the solution to
stand for 10-15 minutes and filter the solution using
either a rapid filter paper, like a #4 Whatman, or a
coffee filter. Collect the solution in an amber glass
bottle, or a bottle covered with aluminum foil, and store
in the refrigerator. A stock solution prepared and stored
following these directions will be good for at least a year.
When you are ready to sow your seed, prepare the media at
least one day ahead. If you purchase dehydrated media for
1 liter of solution (which is enough for 6 flasks), you
will not have to weigh the media. Media preparation
consists of pouring, while stirring, the dehydrated media
into 1 liter of demineralized water contained in the top
section of a double boiler. Add water to the bottom
section of the double boiler, replace the top section
containing the media, and bring the water in the bottom
section to a gentle boil. Continue boiling for about 20
minutes, or until the media has dissolved and is free of
lumps. When completely dissolved, pour 160 milliliters of
media into each 500 milliliter flask, using a funnel to
prevent the media from contacting the neck of the flask.
Stopper the flasks loosely with the rubber stoppers, cover
the stopper and top of each flask with an aluminum foil
square, and place the flasks in the pressure cooker. Heat
and bring the pressure cooker up to 1 kg/cm (15 psi).
Maintain the pressure for 30 minutes. The media requires
several hours to gel, so after you discontinue heating,
either move the cooker to where you will be sowing the
seed while it is still quite warm or allow it to cool
completely before moving.
When you are ready to sow the seed, add 5 milliliters (1
teaspoon) of CaHc stock solution to 40 milliliters (8
teaspoons) of demineralized water. Add white vinegar drop
by drop until the pH is between 5 and 6 using a pH
indicator. This final solution of disinfectant contains
250 ppm (AC). Finally, add 1 or 2 drops of liquid
detergent and set the disinfectant solution aside. Once
the pH has been lowered the solution is only good for a
short time. If you should you be interrupted for an hour
or more, prepare a fresh solution.
The next step is to place the seed, equal in volume to a
half grain of rice or less in one of the small (3-5
milliliter) bottles. One bottle should be prepared for
each flask you will sow. Set the bottles of seed aside and
add 100 milliliters (one half cup) of liquid household
bleach to 900 milliliters (4 and one half cups) of water
in a wash pan or other shallow container. Add 10
milliliters (2 teaspoons) of sodium bicarbonate to the
bleach solution to make the solution easier on your skin.
Put on a pair of disposable latex gloves and place 2 hand
towels, of tightly woven material, in the wash pan.
Submerge the towels in the bleach and wet the surface of
the gloves with the bleach solution. Next, take the seed
bottles and add the dilute CaHc solution (200 ppm of AC)
to each bottle leaving a small air space at the top.
Firmly cap each bottle after filling, and when all of the
seed bottles are filled, shake the bottles briskly to wet
the seed. Shake the bottles occasionally for the next
10-15 minutes. While the seed is soaking, open a sheet of
newspaper next to the pressure cooker and wash pan. Wring
out the hand towels and spread them open on top of each
other on the newspaper. Now drop the bottles containing
the seed in the bleach in the wash pan. Release the lid on
the pressure cooker, remove 1 flask, and set the cooker
lid back on the cooker. Place the flask on the bottom
towel and under the top towel so that the flask is
completely covered. Rinse your gloves in the wash pan, and
remove one of the seed bottles and place it under the
towel next to the flask. Working under the towel, remove
the aluminum foil cover and the rubber stopper from the
flask, taking care to keep the stopper under the top
towel. Give the seed bottle a shake and quickly remove the
cap. Pour the seed and disinfectant into the flask and
replace the rubber stopper. Leave the flask under the
towel and wait 1 to 2 minutes. Still working under the
towel, tilt the flask slowly on its side at the same time
withdrawing the stopper sufficiently to allow the
disinfecting solution to be poured from the flask. If you
tilt the flask with a gentle movement, most of the seed
will remain on the surface of the agar. Reseat the stopper
and remove the flask from under the towel. Set the flask
aside, remove the second flask from the pressure cooker
and place it under the towel. Rinse your gloves in the
wash pan and repeat the seed sowing process until all of
the flasks have been sown. Don't forget to have a system
to label each flask either before or after they are sown.
When all of the flasks have been sown, place one drop of
copper sulfate solution on the cotton in the rubber
stopper and one drop in the crack between the neck of the
flask and the rubber stopper. Cover the stopper and the
top of the flask with a fresh aluminum foil square and
place the flask in a warm and bright location, but not
direct sunlight. The final step is the hardest part of the
procedure, waiting for the first signs of germination.
By following this simplified seed sowing procedure, even
those without previous experience can achieve good
results. If this is your first attempt at seed sowing, it
would be a good idea to make a dry run using just the
empty equipment before you try it with seed. Each
operation is a critical so don't alter the procedure
before giving any modification careful consideration. In
addition remember that this is an alternate procedure, the
preferred procedure remains removal of all disinfecting
solution by filtration followed by several water rinses
before the seed is added to the flask.
It is hoped that you will be encouraged to try sowing your
own seed. From my own experience, I believe that there are
few events in life that are more satisfying. Join me in
watching your own seed turn green and grow into viable
plants.