If you want to grow new plants from seeds, here’s what you need to know about buying versus gathering seeds and sowing seeds and transplanting seedlings.
Buying Versus Gathering Seeds
In nature, all flowering plants reproduce themselves from seeds that fall to the ground when ripe. These seeds usually spend time under the cover of dead leaves and germinate when conditions are suitable.
Cultivated plants can also be propagated from seeds, but the offspring vary. Although most of our garden plants originated from species growing in the wild, they have been hybridized to produce different and often improved forms. When seeds from these hybrids are collected and sown, the plants will differ and will usually be inferior to the parent. Always store collected seeds in a closed container kept in a cool place until they are sown.
Consider growing seedlings in a nursery bed, saving only the most attractive ones. Of course, in order to perpetuate a seed-raised strain, subsequent plants must be propagated by cutting or division.
Commercial seeds can usually be relied upon to produce true to type seedlings (or variable seedlings having desirable characteristics), and they provide an inexpensive means of raising plants.
Sowing Seeds and Transplanting Seedlings
Sow seeds in mid to late winter in a greenhouse or under lights. Window light is seldom adequate. In mild climates, sow seeds in a cold frame or sheltered bed.
When sowing small quantities of seeds indoors, the simplest method is to plant only one kind in a pot. Fill the pot to about ½ inch below its rim with a commercial seed-starting mixture or your own sterilized formula (equal parts of soil, peat moss, and perlite). Level, firm gently, water with a fine spray, and let drain.
Sprinkle the seeds, evenly but thinly over the surface; cover with 1/8-inch layer of starting medium. Leave fine seeds uncovered.
Cover the seed container with a pane of glass or a plastic bag to retain necessary moisture and warmth for germination. Keep the container out of the sun to avoid excessive heat. Most seeds germinate at 66°-70°F. Depending on the kind, seedlings should appear in about one to three weeks. When they do, remove the glass or plastic coverings.
When seedlings are large enough to handle easily, transplant to a flat pot filled with sterilized soil, and space 1-2 inches apart. Give them all the sun and light available to prevent weak, spindly growth. As seedlings become crowded, pot individually.
Before setting the seedlings out, acclimate them to outdoor conditions by putting them in a cold frame or sheltered spot in the garden. Set pots or flats on the surface of the soil , and lightly shade for a few days; then gradually admit more air and light. Later transplant to an out-of-the-way bed for further growth. In later summer of the same year, plant in permanent positions, or wait until the following spring.
For an early start in cold climates, outdoor seed sowing is best done in a heated frame. A soil-heating cable set for 65°F is satisfactory. In an unheated frame, sow about six weeks prior to the last spring frost. Prepare soil in frame by adding peat moss or perlite, so that it will not crust over and deter the emergence of the seedlings.
Sow seeds shallowly in rows or in pots as previously described. Shade the frame with burlap until seeds germinate; then give full light, ventilation, and moisture. Transplant as needed into well-spaced rows or pots in the cold frame, and then later to the garden.