When I told my daughter that I was writing this article, she said, “Be sure to tell them that they don’t have to save forget-me-not seeds because they stick to your socks and get spread around the garden that way....Oh, and don’t forget to tell them that nigella and poppy seeds are fun to save because you can pretend the pods are salt and pepper shakers.” She has some good points. The first is that you probably don't need to worry about saving seeds from self-sowing annuals, unless you want to give them to your friends. If you want to grow them in another part of the garden, simply gather the seeds when they are ripe and scatter them in the new location.
Another point is that seed saving is an adventure for the whole family, and children or grandchildren should be involved. What better way is there to insure the future of our plant heritage than to teach children how to save seeds?
Although saving flower seeds is a mostly straightforward and intuitive process, I have a few tips that should make it easier to get started. There are five basic steps to seed saving: observation, harvesting, drying, cleaning, and storing.
Observation means that the plants will let you know when their seeds are ready to harvest if you pay attention and become acquainted with their life cycles. Seeds must be harvested at the right time for maximum viability. They are produced in either pods or seedheads. Pods are ready to harvest when they become dry and brittle, just before they split open and spill their contents. A good example is the sweet pea. If you pick the pods too early, the seeds will be green. But if you wait too long, the pods will pop open, scattering the seeds. Choose the ripe pods by feel. They should start to split when you squeeze them. Poppy seeds are produced in pods that resemble salt shakers. They are ready to harvest when the pods snap off the stems. If they bend, give them more time. Flowers like cosmos and zinnias produce seedheads. When the seeds are ripe, the seedhead shatters. They are also harvested by feel. I can tell when they are ripe because the seedhead falls apart in my hand when I rub it. Color is another clue: calendula seeds will turn from green to brown when they are ripe. When going out to harvest seeds, I stuff my pockets with snack-size ziploc bags, which are perfect for small amounts of seed. I use stainless-steel mixing bowls for larger quantities. Other equipment includes pruning shears and thorn-proof gloves for harvesting eryngium seeds.
Never harvest wet seeds. It’s better to wait for dry weather. Seeds should be dried in a well-ventilated room with a temperature between 70 and 95 degrees. Alternatively, you can dry seeds in a garage, out of direct sunlight.
It’s not always necessary to remove the seeds from the pods before drying them, as long as they were not harvested wet. One exception is lavatera. I’ve had problems with lavatera seeds going moldy if they're not cleaned the same day they are harvested. When harvesting pods from plants like sweet peas and lupine, cover the mixing bowl with a piece of window screen, cheesecloth or other lightweight fabric that will allow air circulation while preventing the exploding pods from shooting the seeds out of the bowl. Or put them in a paper bag and close the top.
Small quantities of seed can be dried in plastic cups, on small plates, or in snack-size ziploc bags, propped open with toothpicks to provide air circulation. It helps to shake down the seeds to a thin layer so they'll dry evenly. Turn or stir them every few days. Be sure to label the container with the name of the plant. Most seeds require 2-6 weeks to dry completely. Drying time depends on the size of the seed, as well as the temperature and humidity of the room.
Seeds can be cleaned after drying for a few days. The chaff is easier to remove when it's dry, but the seeds will need further drying after they are cleaned. The following equipment is useful: different sizes of stainless-steel mixing bowls, a box fan, and a kitchen strainer with a metal screen. I use several different methods for cleaning seeds. Here are some examples:
Poppies: Place the pods in a gallon-size, plastic bag. Close the top, and shake vigorously until the seeds fall out of the pods. Dump the contents into a strainer held over a mixing bowl. Shake the strainer until all the seeds fall through, then throw away the empty pods. With the box fan turned on low (outside the house, of course), slowly pour the seeds back and forth between two mixing bowls until the dust is blown away. Spread the clean seeds on a plate or a cookie sheet to finish drying. Zinnias: After drying for a few days, loosen the seeds from the chaff by rubbing the seedheads vigorously between gloved hands. Use the mixing bowls and fan, as described above, to remove the chaff. Campanula and other tiny seeds: These dust-like seeds cannot be cleaned with a fan. After putting them through a strainer to remove the largest pieces of chaff, blow on them with your breath while shaking the mixing bowl. It takes a while to get the hang of it, but soon you’ll be able to get the seeds perfectly clean. Please wear goggles to protect your eyes from the irritating dust. This is not a good activity for people with contact lenses, asthma or sinusitis. By the time I’m finished cleaning the large amount of seed that I need for my business, I’m covered with dust and itching all over. Now it’s time for a shower and some Xlear nasal spray. Once the seeds are totally dry, they should be stored in a cool, dry, dark place. We have a cold storage room in our basement, but a refrigerator works, too. If you are only saving the seeds until the next planting season, you can be less concerned about temperature – even a bedroom closet will work. Don’t store seeds in a humid place like the kitchen or bathroom, or in a place where the temperature fluctuates like a garage. Some seeds require refrigeration after harvesting to improve germination. The following seeds are always stored in the fridge: belamcanda, daylily, lily and hibiscus. To protect them from humidity, store them in airtight containers like glass jars or ziploc bags.
I don't think a gardener can really appreciate the life cycle of plants until they have tried saving seeds. I used to deadheaded my plants to prolong the bloom season. But now I appreciate plants in all their stages of life. To me, the seed pods and seedheads are just as beautiful as the flowers. You know the saying: “All the flowers of all the tomorrows are in the seeds of today.”