As a gardener, the entire experience associated with having a garden is incredibly fulfilling and satisfying. There is little that compares to the satisfaction of seeing things sprout, grow and ultimately bloom when you planted the seeds for the blooming flowers yourself. Many flowers produce seeds after the flower has bloomed.
Harvesting seeds from the flowers that you've planted can be every bit as rewarding as the experience of watching your seeds sprout, grow and bloom. Saving seeds is one of the ways in which gardening can be very economical even when people are facing horrible economic hardship.
Here are some explanations of how the seeds on a selected list of flowers form. I will also explain how you can identify them and how to go about harvesting the seeds once they are ripe.
Some flowers produce seeds that form directly from the flower head. With these types of flowers, it is necessary to leave the flower head on the plant so that the seeds can mature and ripen. Other flowers such as Hibiscus and Rose of Sharon produce pods that grow and mature after the flower falls off the plant. The seed pod remains on the plant and grows larger. When it finally reaches its fully mature size, the pod will start to ripen and dry out.
With flowers like cosmos, zinnia, marigold, coreopsis, calendula, all types of daisies, any flowers in the Rudebekia family, and even canna lilies, the seeds will form right where the flower is. For these flowers, in order to get seeds, you must leave the flower on the plant. Leaving the flower on the head goes contrary to what people think they need to do to keep their flowers blooming.
Normally, it's important to deadhead flowers after the flower has bloomed. Dead-heading flowers may promote more blooms, but it stops the seed producing process before it starts. It isn't possible to deadhead flowers and still harvest seeds.
Cosmos, daisies, coreopsis, marigolds, zinnias, calendula, and similar flowers produce seeds that tend to be dark in color, and long and narrow. These seeds are generally found in the area inside the flower head, right around where the pollen center is. They are long and thin. Once the flower head has completely dried, you should be able to pick off the flower head and have the seed fall out easily.
With canna lilies and flowers like four o'clock, the seed looks like a dark black ball. The canna seed is slightly larger than that on a four o'clock. After the flower has bloomed, the spent bloom typically falls off all by itself. There is a residual area left after the flower falls off, and inside this area, a seed will form.
Eventually, it will be easy to see the seeds and if you shake the four o'clock branches, the seeds will fall out. It's a good idea to have a paper bag that you can hold under the branch while you shake it. With canna lilies, there will be a round and fuzzy like ball that you will see where the flower had been. As long as you leave this fuzzy ball alone, the seeds inside will grow and mature. Once the ball dries out, it will burst open a bit and you will see seeds. Not all of these balls will contain seeds.
Datura, a self seeding annual that is a member of the night shade family produces seed pods that look like a walnut shell with sharp thorns all over it. The pod will start out small and it will be green. As it matures, it will get larger, until it is ultimately about the size of a walnut. Once it reaches its full size, it will start to dry out. When it has fully dried out, it will burst open. It is important to wear protective heavy duty gardening gloves when you harvest these seeds.
When you harvest seeds that are still on the flower head or in a pod, it's not unusual for the seeds to become attached to chaff. Chaff is the stuff that's stuck to the seeds but that can sometimes make it harder to identify the seeds. After you have harvested your seeds, it is important to separate the seeds from the chaff.
Separating the seeds from the chaff will be easier if the seeds are fully dry. To dry the seeds, place them on top of a paper towel that you place on a paper plate. Be sure to label each paper plate so you know which plate contains which seeds. Place the seeds in a dry place where they won't be disturbed.
Once the seeds are completely dry, you can separate the chaff from the seeds. If you have a a wire mesh colander or fine mesh basket, you can use that. Make sure that the mesh isn't too fine. If it is, the seeds won't fall through the holes. You want the seeds to fall through and the chaff to remain in the mesh.
As soon as you have all the seeds separated from the mesh, you might want to put the seeds in an envelope or in a small Ziploc craft bag. Be sure that your seeds are completely dry before putting them in a container. Even the slightest bit of moisture will cause the seeds to mold.
Label each envelope or Ziploc bag in which you place seeds. The best way to store your seeds is to have a box of some sort where you create a kind of file system. Use dividers. You can make your own dividers using recycled cardboard from boxes, from tissue boxes or anything you have on hand.
You can use colored permanent markers so that you know what is supposed to go where. You can separate your annuals and perennials or you can get more specific and separate things by flower color, height, bloom time or any other distinction.
Although the process of harvesting, drying, saving and storing your seeds is labor intensive, there is so much to be learned about growing things when you save the seeds. Not only that, you are saving seeds that you will be able to plant the next spring, thereby saving a considerable amount of money. Many seed savers also save seeds so that they can trade their seeds for different seeds with gardening friends.