Just like plants, seeds are living things--small embryonic plants enclosed in a "seed coat"--and must be cared for to ensure they grow into plants. A seed is the product of reproduction in seed plants such as flowering annuals or fruits.
Seeds vary in size, from very small such as the orchid's dust-like seeds (about one million seeds per gram) to larger woody plants' large seeds (about 10 per grams).
Annuals produce large amounts of smaller seeds during a season. This is nature's way to ensure that a few will end in a favorable place. Perennials often have larger seeds, and produce the seeds over several years.
Parts of a Seed
A seed is made up of three parts: the seed coat, which protects the embryo; the endosperm, which is food for the germinated embryo; and the embryo, which will develop into a plant.
When you purchase a seed it is in a dormant stage. The seed coat allows the embryo to "wait" for planting until conditions are favorable.
Once a seed is germinated, the embryo has three distinct parts: the primary root, which will penetrates the soil; the cotyledon(s), which serves as food for other parts of the embryo and embryonic leaves, which are the shoots coming up through the soil after planting.
Seeds germinate when exposed to water. The embryo swells and burst through the seed coat. Germination can take as few as four days and as long as 21 days, depending on the plant. Because the embryo does not have leaves at this point and cannot create food through photosynthesis, the endosperm provides a high nutrient food during the germination stage. Water is critical--that is why it is important to plant in moist soil and water thoroughly after planting.
Where to Get Flower Seeds
Gardeners can find a large variety of flower seeds in catalogs. But choices and term such as hybrid and over-pollination can be confusing to the novice gardener. Garden centers sell flower seeds in smaller packets. The packages often have colorful pictures of the the mature flower. Planting instructions and regional planting zones are often found on the back of the seed packet.
You can also harvest seeds from flowers in your garden. To harvest: place a small paper bag over the flower head and tie with a string (gently). Use garden scissors to cut off the flower head below where the bag is tied. Hang the bag in an airy place, this will allow the seeds to fall into the bag. Be sure to label and date the bag.
Storing Flower Seeds
Flower seeds must be stored in a cool, dry place and can be kept up to four years.
If storing your own harvested flowers, lay out the seeds on a flat surface away from sunlight after harvesting. Allow to dry for about a week. Then place in an airtight container such as one used for food storage or a paper envelope. Be sure to label and date the container. Packets of flower seeds, purchased at a garden center, should also be stored in an airtight container to avoid moisture.