The most obvious reason for growing plants from seed is the lower cost per plant. This is especially important if you are growing many plants for a profit. Growing from seed for pleasure may be another reason. Children, as well as adults, can learn much about how plants grow by starting from seed. Another reason is that many varieties can only be started (or are easier to start) from seed. Often we cannot find the particular specimen we want at our local nurseries (or if we do, it is often very expensive) which leaves the option of growing from seed because seeds of nearly anything can be found in mail order catalogs or on the internet. The GreenDealer Seed Catalog is one of the best sources for exotic seeds. These seeds can be ordered and received in a few days (or weeks) depending on how exotic the variety may be and how readily available they are.
A seed is produced from the flower of the parent plant. The blossom, containing the seed consists of the the male and the female parts. The male part is called the "stamen" and consists of the "anthor" and the "filament". Located in the anthers is the pollen which is transferred to the female part of the flower for fertilization (germination). This female part of the plant is known as the pistil which consists of the "stigma", the "style", and the "ovary". After this germination takes place, the seeds will grow in the ovary until they are ready to be dispersed.
The transfer of the pollen from the male part (stamen) of one flower to the female part (pistil) of another flower is done by insects, wind, or in greenhouses by hand using a small paint brush. Many hybrids are created by this method of hand pollination. The seeds from such hybrids will not produce the same kind of plants in the next generation however, and will usually produce inferior plants, revert back to one of the grandparent plants, or may produce no plant at all.
The dispersal of seeds in nature is accomplished by wind or by animals carrying the fruit or seed to other locations where many of the seeds will find an opportunity to establish themselves.
The outer shell of a seed is known as the coat and functions to protect the embryo (dormant plant) and the endosperm (food source) in the interior of the seed. In some species this coat is so hard that it must be softened in water, or nicked to allow the process of germination to begin. One end of the embryo will become the root while the other end will produce the top, stem or the beginnings of leaves.
To coax a seed into germinating it must be mature and viable and it must receive the proper conditions of light, moisture, temperature and air. Many varieties of seed such as some trees, shrubs and annuals such as vegetables and herbs will germinate with little help from the gardener. They may in fact germinate under far less than ideal conditions. Other varieties of seed such as Perennials and seeds with exceptionally hard coats may need ideal conditions and some assistance in the process of getting started. A few varieties may need special attention such as artificial and constant light: Columbine, Sweet Alyssum, Impatiens, Lettuce, Flowering Tobacco, Oriental Poppy, Yarrow, Salvia, and Savory. Others may need complete darkness for a period of time such as: Borage, Larkspur, Coriander, Forget-Me-Not, Periwinkle, Sweet Pea, Delphinium, Fennel, Phlox, Verbena, and Viola. It is important to know about these requirements if you are to grow any of these or other species. Some research into these various species may be required.
Most seeds will benefit from being soaked in warm (even hot but never boiling) water. The addition of a small amount (1/2 teaspoon per pint of water) of saltpeter (sodium nitrate) to the water may help many varieties of seed with very hard seed coats. Soaking for a few hours up to as many as 48 hours in the case of seeds with very hard coats will speed up the germination process. After soaking, blot them a bit with paper towels and plant them in the growing medium immediately or before they have a chance to completely dry out again.
Some varieties of seeds have such hard coats that water is prevented or impeded from being absorbed into the seed. Soaking may not give the embryo inside the seed enough of an advantage in breaking through the coat. In such cases it is necessary to nick the coat with a file, sandpaper or slightly crack, scar, or cut into the seed with a knife being very careful not to damage the embryo inside. If the kind of seed you are scarring has an "eye", avoid that area. If you intend to scar seeds that are too small to handle, tack a piece of medium grain sandpaper over a scrap piece of board. Wrap another piece of sandpaper around a scrap block or piece of 2 x 4. Place the seeds on the sandpaper attached to the board and gently rub the seeds with the sanding block or 2 x 4 scrap. It will only take a few passes between these 2 pieces of sandpaper to adequately scar the seeds. Too much of this grinding action may damage the seeds. If you intend to scar small or very small seeds, put a piece of coarse sandpaper, coarse side facing seeds, into a jar or coffee can. Add the seeds and shake for a few minutes until the seeds have been scratched a bit by the sandpaper. After scarification the seeds may still benefit from soaking before being planted into the growing medium.
Some seeds such as many Perennials (i.e. lettuce) have dormant embryos when they are collected. Some of these kinds of seeds will go dormant if stored for a few weeks at temperatures above the mid 70s. These kinds of seed need a moisten & chill process "stratification" before they can be planted into the growing medium. Mix the seeds with about three times their volume of the growing medium in which they will ultimately be planted and place this mixture into the refrigerator or freezer. If seeds have already been chilled in either water or in their packets this stratification will not work and the seeds are unlikely to germinate. Use this method on only freshly collected seeds. Outdoor stratification or stratification in a cellar or other cold storage bin can be accomplished if the temperature remains below 40 degrees f. for 6 to 12 weeks. In this case the seeds could be sown directly into the flats of growing medium and planted into the ground to a depth equal to the depth of the flat. Protection from heavy rains, direct sunlight and wind will be necessary. In a cellar or cold frame this additional protection is not needed but a bit of moisture may be required to keep the mixture from drying out during the winter. In the spring, as the soil warms up these seeds should germinate.
Any kind of plastic container at least 3 to 3 1/2 inches deep will work. Used containers should be rinsed with a solution of about 1 part bleach to 9 or 10 parts water. Rinse and dry thoroughly before using. I have used the containers that supermarket delicatessens use for salads and pastries, etc. The only problem with them is that holes must be punched at the bottom for drainage. Then some kind of tray is needed below that to catch the overflow of water. The flats that are designed and manufactured specifically for germinating seeds seems to be the best solution over all. They are available with a variety of pocket inserts for various sizes of plants. It is possible to graduate from the smaller pocket inserts to larger ones as the plant begins to grow. They already have holes at the bottom that allow the excess water to drain into the tray in which they are snugly placed. The drainage of water is very important because soil that is too damp will either cause the seeds to rot or will allow the growth of mold, fungus and other diseases - one of the worst enemies of seeds trying to grow into seedlings. There are clear plastic lids that can be placed over these nursery flats to prevent drafts and to protect seeds from cold drafts. As the plants begin to grow these lids need to be set off center to allow air flow and finally removed completely to allow the young seedlings adequate air flow. These flats can be reused year after year as long as the 1 part bleach to 9 or 10 parts water solution is used to wash them and then allow them to dry just before reusing.
Growing Media, or Germinating Media is plural for Growing Medium or Germinating Medium, This is the material in which the seed is placed to germinate and grow. Of the various growing media, you will need to select the medium that is best for your specific purpose. Listed here are some of the options that are widely available for the gardener.
Peat moss is made up of decomposed aquatic plants and can be very acidic. It retains water and may not allow for adequate aeration or drainage. For this reason it is frequently used with other substances but not by itself.
Sphagnum moss is made up of dried bog material. It is fairly sterile and because it is very lightweight it can absorb as much as twenty times its weight in water. Its value as a fertilizer is not very good, and its ability to absorb water evenly is not very desirable. It, like Peat moss, is a good addition to make up a growing medium but is not the best substance to use by itself.
Vermiculite is expanded mica. It can retain a large volume of water for long periods of time. Although it contains a high level of magnesium and potassium and can hold nutrients and is good for aeration,it is not used by itself but is yet another ingredient in a final mixture for germinating seeds.
Perlite is a volcanic ash. It holds water on its surface but does not allow much absorption. It has no elements needed for plant growth and does not hold nutrients well. It does promote good aeration , stays cool and is a very good ingredient as part of a growing medium.
Sand is a good choice for root cuttings but is a bit too heavy
for germinating seeds, it does not hold water, nor nutrients and
is not recommended for germinating seeds.
Rich garden soil is good for plants but it does not offer the
conditions necessary for germinating seeds because it does not
allow for proper aeration and drainage for seeds. It is not sterile
but after sterilization (bake it in a pan at 180 degrees for 30
minutes) it can be used as an ingredient in a good growing medium.
Special mixtures prepared for germinating seeds are available at nurseries and garden centers. These are very good for starting your seeds. For a little less money you can prepare your own mixture. Mix 1/3 to 1/2 sphagnum or peat moss or any combination of both with 1/2 to 2/3 vermiculite or perlite or any combination of both will make a very good growing medium for germinating most any kind of seed. The ideal mixture would have about 50% solid material, 25% air space (oxygen) and 25% moisture.
It is generally more economical to germinate seeds during the warm months when the heat and light from the sun is free. Temperatures generally in the mid 70s up to 80 degrees f. are needed to germinate most seeds. Although there are seeds that require 70 degrees and lower. When temperatures inside drop below 70 degrees at night the germination of many kinds of seeds can be impeded or even halted. It is important to keep the seeds at a constant temperature and away from drafts such as too close to doors and windows. If they are growing near a window to take advantage of the light during the day, it is a good idea to move them farther back as the sun sets to avoid exposing them to drafts. The lack of constant heat is one of the main reasons that seeds fail to germinate.
Seeds can be germinated during the winter months however and the advantage is that you will have an earlier crop since you can plant young plants outdoors in the spring rather than starting the gmination of seeds in the spring. When germinating seeds indoors during the winter or indoors in air conditioned environments it is important to keep the soil warm. There are several ways to accomplish this. In greenhouses heating coils can be used. For smaller batches of seeds in the typical home it is possible to set the seed flat upon blocks and put a 40 watt light bulb underneath the flat. 60 to 100 watts are likely to generate too much heat. The soil should feel warm, but not too warm. Care should be taken to avoid contact with flammable substances. A heating pad placed beneath the flat or seed containers can be used but care is needed for this too since the controls on some of these heating pads will allow too much heat. Again the soil should feel comfortably warm not too warm or hot. See our Do-It-Yourself Seed Germinating Kit Plan.
Besides warm soil, the air in the room where most kinds of seeds are germinating will need to be at least in the 70s. The higher up you place the seed flats the warmer the air is likely to be in any room. Since heat rises, the top of a refrigerator would be warmer than on a table at waist level. If the room temperature is 70 or 72 degrees f. the difference of 2 or 3 feet of height where the same room may have temperatures from 74 to 78 degrees f. can make the difference in whether or not some kinds of seeds will germinate. Those that require lower temperatures should be placed at lower levels within the room.
Once the seedlings appear and begin growing into plants, the heat should be reduced to around 65 to 70 degrees f. during the day with temperature as low as 55 to 65 degrees f. at night. There are exceptions to this. Melons, cucumbers, eggplant, peppers, tomatoes,and nearly all tropicals will prefer 70 to 80 degrees f. during the day and 60 to 70 degrees f. during the night.
Light is not the same thing as heat. Although heat is generated by a light source such as the sun or artificial light, it does not continue generating heat when the lights are turned off or when the sun sets. The heat required to begin the germination process should remain constant, day and night, at least during the early stages. The light source may or may not remain constant, but will be necessary for long periods. Simulating the longer daylight hours of spring - 10 to 12 hours per day is best for most species. Those seeds that require constant light will need artificial light (fluorescent or grow lights are best) until germination occurs and possibly for some period of time afterwards. Seeds that require total darkness should be covered with black plastic until germination occurs. Once germination has occurred, all seedlings will need enough light for photosynthesis to enable them to develop into strong healthy plants. If seedlings are growing in overcast conditions of winter the continued use of artificial lights will be required.
The use of grow lights, which do not generate much heat (if any) can make germinating seeds a much easier task. Just as the case where the special germinating medium is the best for growing seeds and the special nursery flats with inserts and clear plastic lid are best - grow lights are the best source of light for germinating seeds because that is what they were designed for. The best tools for the job will usually provide the best results. When using grow lights position them 6 to 8 inches above the seeds. As the seedlings begin to grow, raise the lights so that the tops of the seedlings are always 6 to 8 inches from the light. When there is an absence of adequate sunlight such as the overcast days of winter, it is best to leave the lights on 24 hours a day, even for those plants that do not require constant light. The seeds will germinate faster and will have less time to effected by harmful diseases that can occur in cool, overcast, damp conditions. After the seedlings have grown into small plants, gradually reduce the amount of light until they are receiving 12 hours of light per day. If you are germinating a lot of seeds, you will have an investment in time and money. The use of an automatic timer will help in regulating the light and will help protect your investment. After the plants are 4 or 5 weeks old they are likely to be strong enough to begin reducing night time temperatures. It is best to continue using the grow lights 12 hours per day. As the plants continue to grow, they can be introduced to a greenhouse or even taken outside if there is adequate protection against the elements. The leaves are likely to be tender and will not do well in direct sun, heavy rain or windy conditions. Treat them like the babies they are and pamper them. If the night temperatures are below 55 degrees f. they should be brought back in for the night.
Before sowing seeds in the growing/germinating medium water it thoroughly and let it drain off. Sow seeds and cover with plastic, glass, or with the specially designed clear plastic covers that can be purchased with the nursery flats. These seeds will probably not need to have anymore water nor mist added until after germination occurs but it is still a good idea to check the top of the growing medium daily to be sure. Too much water (inadequate drainage) will cause seed rot, mold, or fungus. Check the growing medium every morning. When the top layer feels a bit dry it can be misted. Watering from the usual containers can disturb the seeds. It is best to sprinkle lightly or better yet, use a spray bottle with a mist attachment. This fine spray will lay down a nice amount of moisture and will not cause gullies or pockets to disturb the seeds. Water is best at room temperature or even a bit warmer - never use hot water nor water that is too cold such as cold water right from the tap. The best time to water is in the morning. Do not allow the growing medium to dry out and do not water so much that is remains soggy or wet. Always water from the top (a mister is best) rather than rely on adequate moisture to soak up from the bottom of the tray. The growing medium needs to be watered from the top down to assure an even distribution of moisture throughout. too much moisture remaining at the bottom of the tray will cause problems associated with inadequate drainage and the layer at the top may remain too dry.
The first growth to appear on the seedlings are the cotyledons. These are not true leaves but are food storage cells. This food will only last the seedling a short time and it will be necessary to begin feeding the young plants just as soon as the first true leaves begin to appear, usually within a couple of weeks. Purchase a good quality all purpose water soluble plant food such as Miracle-Gro. Always read the label. When fertilizing young seedlings, start out with a mixture that is about 1/4 the strength that is recommended for mature plants. Use this solution about once a week. Gradually increase the ratio as the plant grows and becomes stronger. After several weeks and the plant seems strong and healthy increase the mixture of plant food to water to the full strength as recommended on the label. Do not believe, in the case of plant food or fertilizer, that "more is better". The manufacturers test their products and know what formulae is best. Follow the instructions on the label.
"Damping off" is the expression used to describe the condition caused by various soil diseases that are the most likely problem in germinating seeds. This problem may occur before the seedlings have had a chance to appear, after the seedlings have begun growing or even after the plant has been growing for several weeks. The appearance of a white growth is most common. There is little chance of the seeds germinating once this condition is noticed. If the condition appears after the seedlings have started growing the damage usually occurs very fast and the seedlings will wilt and die within a few days or even hours. "The various damping off" diseases are: Fusarium, Pythium, Phytophthora and Rhizoctonia. There are others as well. Some cause the damage below the surface to the seedling's roots and may not even be visible. In the greenhouse environment the diseases can be conquered by specific kinds of gases and smokes. For the small scale gardener the use of fungicides is safer more practical. Early detection and treatment is very important which is why it is so important to check the seeds and seedlings daily. There are good fungicides for controlling these "damping off" problems. Your local nursery or garden center will have such products as: Captan, Dexon, and Subdue that if used soon enough after the problem is detected should solve the problem. As always, follow the direction on the label or package. Always use a mister to apply the fungicides and do so right after the seedlings have been watered.
Do not use fungicides unless there is a problem. Prevention of "damping off" diseases is always better than trying to catch the problem before damage is done. The best precautions are:
1. Always use a sterile growing or germinating medium
2. Always use new or sterilized (bleach water solution) flats, trays or other containers
3. Use same bleach solution to sterilize tools.
4. Keep hands clean while handling the various seeds, tools, growing medium, etc.
5. Always make sure seeds are clean and free of any mold or fungus
6. Don't sow too many seeds in a small area, they need space and air circulation
7. Use a mister with clean warm water and never over water or let water stand in trays or germinating containers
8. Make sure there is adequate heat and light
9. Use a plant food but do not over fertilize
10. Grow the plants as fast as possible to get them through the vulnerable period sooner.
When germinating several species or even a single kind of seed it is important to note what the species is on some kind of label. Keep track of dates and other information so that any mistakes can be backtracked in future attempts to germinate the same kind of seed. A single label may represent an entire flat of the same kind of seed, but when the seedlings are transplanted, more labels will be needed to keep track of the kinds of plants you are growing. Even if you are thoroughly familiar with a particular species, young seedlings are difficult to recognize until they have matured enough to acquire the characteristics that are familiar for that species.
Always transplant into clean containers or into good soil in the garden. Do not expose the young plants to direct contact with wind, heavy rain and direct sunlight immediately. Overhead protection and filtered light will offer a gradual transition into the outdoors that most plants need to survive.
It is a good feeling to look at a crop, a tropical house plant, cactus, vine, herb or tree and know that you have helped it to flourish into the wonderful specimen that it has become. When I look at some of the huge trees that I have planted years ago - it is with amazement that something so small and fragile as a seedling could grow into something so grand and stately that now I can seek shelter from the pounding summer rain under its massive foliage.
Good luck with your seeds!
Also, see our new
report on germinating seeds in clear plastic zip-lock bags.