Seed propagation of plants

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Seed Propagation of Plants
Guide 400 H-112
Seed propagation is often used to produce large
numbers of plants inexpensively. Generally plants
grown from seed take longer to reach maturity than
those propagated vegetatively, but the low cost may
compensate for the time lost.
The fact that plants sometimes do not come true
from seed and that no two seedlings are exactly
alike can add interest to this method of propagation.
Variations among seedlings enable plant breeders to
produce new varieties. Interesting as it is to look for
new plant types, variability is undesirable if uniformity is needed in new plants.
Seed propagation is not difficult, but it involves
careful management of germination conditions as
well as knowledge of the seed requirements of the
species.
Testing Seed. If the requirements for germination
are not known, a germination test will be helpful in
indicating the necessity for any pregermination treatment.
To test seed for viability and germination, select a
small but representative sample from the lot under
consideration. One method of testing is to place a
moist paper towel on a flat surface, then making a
row of seeds so that they may be covered with an edge
of the toweling. Then roll the towel and place more
seeds and continue the process. Rolls should not be
tight with about five layers. Larger seeds may be
placed in germinating trays - sterile sand flats. Temperature for these tests should be about 65 to 75°F.
The results of these tests would give the germination at those temperatures and also indicate whether a
pre-treatment such as scarification or cold is necessary.
Scarification involves scratching the seed on sandpaper or other abrasive. This allows water to enter the
seed more readily.
Preparing the Germinating Mixture. Seeds may be
sown in various materials. Popular germinating media
are sand, sphagnum moss, peat moss, vermiculite,
perlite, and soil, or mixtures of these media. Any
medium or mixture used should be well-drained and
sterile. Vermiculite and perlite, as a result of their
preparation, are sold sterile; those media coming from
nature should be sterilized before use. Sterilization
kills weed seeds, insects, and disease-causing organisms.
To sterilize the media it should be held at a temperature of 160°F for 45 minutes. An easy method is to
place moist soil in a pan. Wrap a medium potato in
aluminum foil and place on top of the mound of soil.
Cover the pan with foil to avoid drying the soil.
Bake the soil at 350°F in the oven until the potato
is cooked and PRESTO-the soil is sterile. Or you can
wait to sterilize the soil until it is in the container.
Fill the germinating container with soil mix to a
quarter-inch from the top. Moisten with water until
the medium can be made into a ball which crumbles
easily but is not muddy from excess water. Once this
is completed, sterilize both the medium and container
by placing in the oven for one-half hour at 180°F.
After the soil mix has thoroughly cooled, level and
tamp it gently to make a firm seedbed. Apply about
one-quarter inch of sterile, seed-grade vermiculite to
cover the seedbed. Moisten the soil again by setting
the container in a shallow pan of water until the
vermiculite on topis moist, then remove the container
from the pan of water.
Sowing Seeds. Once the vermiculite layer is moist,
the seeds can be sown. Scatter the seeds uniformly
over the surface of the vermiculite. Do not sow the
seeds too thickly, since crowded seedlings generally
grow spindly or induce conditions favorable to rotting.
Do not cover small seeds, such as those of African
violet or begonia. They are dust-like in size and will
not develop if covered even slightly. Cover the larger
seeds with vermiculite until they are just hidden.
Place the container in a polyethylene bag and seal
the end with a rubber band. Wire loops may be used
to separate the plastic from the fiat to allow for
height of seedlings. Bags used for freezing poultry
and larger items are ideal since polyethylene plastic
keeps the moisture in but allows air exchange. Bags
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