This Post is still under construction!

It is finally February and here in Pittsburgh PA it is finaly time to start seedlings for the coming gardening season...  This blog post is meant to be a guide to plant propogation and will include as much information as I can squeeze out of my head on the subject...  One of the most important parts of sustainability is food production and you can't produce food if you can't germinate a seed... 

Plant propagation is the process of multiplying the number of species, perpetuating a species, or maintaining the youthfulness of a plant. Propagation can be sexual or asexual. Sexual propagation involves taking pollen from a male flower and pollinating a female flower or in the case of a perfect flower taking pollen from the male parts of a flower and pollinating the female parts of the same flower. Asexual reproduction occurs by taking a part of a parent plant and causing it to regenerate into a new plant. Genetically the new plant is identical to its parent plant. Asexual propagation involves the vegetative parts of a plant such as stems, roots or leaves,

Sexual reproduction is the union of genetic material in male pollen with female genetic material in the egg to produce a seed. A seed is made up of three parts: the outer seede coat, which protects the seed; the endosperm, a food reserve; and the embryo, the young plant. When a seed is mature and put into a favorable environment it will germinate.

To obtain quality plants, start with good-quality seed from a reliable dealer. Choose varieties adapted to your area so they will reach maturity before frost. Good seed does not include seed of any other weed or crop and has little debris. If seeds are obtained well in advance of the actual sowing or are surplus seeds that have been stored, keep them in a cool, dry place. Paper seed packs are best kept in a tightly closed jars or containers, and maintained around 40F with a low humidity.

Germination is affected by four environmental factors: water, oxygen, light and moisture.

-Water

Seed germination begins with the absorption of water. Although seeds have great absorbtion power owing to the nature of the seed coat, the amount of available water in the soil affects the uptake of water. An adequate, continuous supply of water is important to ensure germination. Once the process has begun a dry period will terminate the embryo.

-Light

Light is known to stimulate or inhibit germination of some seeds. When sowing light requiring seeds, do as nature does and leave them on the soil surface. If they are covered at all, cover them lightly with fine peat moss or fine vermiculite. These two materials, if not applied to heavily, will permit some light to reach the seed and will not limit germination. When starting seeds in your home, you can provide supplemental lighting with flourescent lights suspended 6" to 12" above the seeds for 16 hours a day.

-Oxygen

In all viable seeds, respiration takes place. The respiration in nongermainating seed is low, but some oxygen is required. The respiration rate increases durring germination; therefore, the medium in which the seeds are placede should be loose and well aerated. If the oxygen supply durring germination is limited or reduced, germination can be severely retarded or inhibited.

-Heat

Also necessary for germination is a favorable temperature. This affects not only the number of seeds that germinate, but also the rate of germination. Some seeds will germinate over a wide range of temperatures, others requirea narrow range. Generally, 65 to 75F is best for germinating seeds of most plants. This should be the temperature of the growing medium, not the air temperature, because seeds are in contact with the growing medium. The importance of maintaining a proper medium temperature to achieve maximum germination percentages cannot be overemphasized. Germination begins when certain internal requirements have been met. A seed must have a mature embryo, contain a large enough food supply, either in the endosperm or the cotyledons, to sustain the embryo durring germination; and contain enough hormones, or auxins, to initiate the process.

-Breaking Dormancy

One function of dormancy is to prevent a seed from germinating before it is surrounded by a favorable environment. In some trees and shrubs dormancy is difficult to break, even when the environment is ideal. Various treatments are performed on the seed to break dormancy and begin germination. Many seeds, like annuals, have no dormancy, so they will germinate without special treatment.

-Seed Scarification

Seed scarification is breaking, scratching, or softening the seed coat so that water can enter and initiate germination. There are several methods of scarifying seeds. In acid scarification, seeds are put in a glass container and covered in concentrated sulfuric acid at about twice their volume. The seeds are gently stirred and allowed to soak from 10 minutes to several hours, depending on the hardness of the seed coat. When the coat has become thin, the seeds can be removed, washed, and planted.

 Mechanical methods of scarificationinclude filing seeds with a metal file, rubbing them with sandpaper, or cracking them with a hammer to weaken the seed coat. Hot water scarrification involves putting the seeds in hot water and allowing them to soak for 12 to 24 hours before planting. There is also a fourth method-warm, moist scarrification-seeds are stored in nonsterile, warm, damp containers where seed coats are broken down by decay over several months.

-Seed Stratification

Seeds of some fall-ripening trees and shrubs of the temperate zone will not germinate unless chilled underground as they overwinter. The "after ripening" may be accomplished by a practice called stratification.

Put sand or vermiculite in a clay pot to about 1" from the top. Place seeds on top of the medium and cover with a half inch of sand or vermiculite. Wet the medium thoroughly and allow excess water to drain through the hole in the pot. Place the pot containing the moist medium and seeds in a plastic bag and tie the bag using a twist tie or rubber band. Place the bag in a refridgerator. Periodically check to see if the medium is moist but not wet. Additional water will probably not be necessary. After 10 to 12 weeks, remove the bag from the refrigerator. Take the pot out and set it in a warm spot in your house. Water often enough to keep the medium moist. Soon the seedlings will emerge. When the plants are about 3" tall, transplant them into pots to grow until its time to set them outside.

Another method involves sphagnum moss or peat moss. Wet the moss thoroughly, then squeeze the excess moisture out. Mix the moss with your seeds and place in a bag or jar. Put the container in your fridge for 10 to 12 weeks and then pot them up as you do in the other method. Handle the seeds carefully. Often the small roots and shoots are emerging at the end of the stratification period. Care must be taken not to break these off. Seeds of most fruit and nut trees can be germinated using these procedures. Seeds of peaches should be removed from the hard pit. Care must be taken when cracking these pits. Any injury to the seed itself can be an entry path for disease organisms.

Starting Seeds

-Media

Seeds can be started in many types of materials, from straight vermiculite or mixtures of soilless artificial media to various amended soil mixtures. The importance of using a sterile medium and container cannot be overemphasized. You can heat a small quantity of soil in an oven. Place the slightly moist soil in a heat-resistant container or pan that can be covered, set your oven to about 250F. Use a candy or meat thermometer to ensure that your mix reaches a temperature of 180F for atleast a half an hour. Do not overheat as this can be extremely damaging to the soil. Just so you know this process can create some very nasty odors so you may want to do this with adequate ventilation Wood or plastic containers and tools should be washed in a mixture of 1 part chlorine bleach to 10 parts water. Try to avoid recontaminating your medium or tools.

Do not use garden soil by itself to start seedlings: it is not sterile, is ussually heavy and will not drain well, and will shrink from the sides of the container if allowed to dry out.

-Containers

You can buy wooden or plastic flats or trays, or make your own from scrap lumber. A convenient size to handle is 12" to 18" long and 12" wide with a depth of about 2". Leave 1/8" cracks in the boards on the bottom of the tray or drill a series 1/4' holes to ensure drainage. Flower pots of either plastic or clay can be used. You can also make your own out of recycled cottage cheese containers, the bottom of milk cartons or bleach containers, and pie pans as long as good drainage is provided.

I like to use products made out of compressed peat that are available at most garden centers. Each cell or minipot contains a single plant, reducing the risk of root injury when transplanting. I prefer peat pellets, they come as a little brown disc that once water is added it will expand into a small cylindar with a hole in the top for the seeds. The nice thing about the peat products is that you can plant the entire pellet/pot reducing the chances of stressing the transplant.

Numerous types of pots and strips are available for starting seeds, plastic cell packs are also available. Each cell or mini-pot holds a single plant, reducing the risk of root injury durring transplant. Peat pelletd, peat or fiber based blocks, and expanded foam cubes can also be used for seeding. Here the growing medium itself forms the seedling container.

-Seeding

The proper time to sow seeds for transplants depends on when plants may safely be moved out-of-doors in your area. This period may range from 4 to 12 weeks before transplanting, depeding on the speed of germination, rate of growth, and cultural conditions provided. A all to common mistake is to sow your seeds to early and then attempt to hold the seedlings back under poor light or improper temperature ranges. This ussually results i tall, weak, spindly plants that do not perform well in the garden.

After selecting a container fill it to within 3/4' of the top with well moistened seed starting mix. For very small seeds, atleast the top /4' should be very fine, screened mix or layer of vermiculite. Firm very lightly the medium at the corners and edges with your fingers or a block of wood to provide a uniform flat surface.

For medium-to-large seeds, make furrows 1 to 2" apart and 1/8 to 1/4" deep across the surface of the container, using a narrow board or pot label. By sowing in rows, good light and air movement results, and if the damping off fungus does appear, there is less of a chance that it will spread. Seedlings in rows are easier to label and to handle at ttransplanting time than those that have been sown in a broadcast manner. Sow the seeds thinly and uniformly by gently tappig the packet of seeds as you move it along the row. Lightly cover the seeds with dry vermiculite or sifted medium if they require darkness for germination. A suitable planting depth is ussually twice the diameter of the seed.

Do not plant seeds to deeply.

This Post is still under construction!  Pregermination and transplanting coming very soon