Autumn vistas are colorful with fall foliage, but frosts and freezing temperatures have pretty much ended the active gardening season.
There are, however, a few harvests left to collect — among them seed from this season’s annual and perennial flowers. I like to let mother nature do most of the work, and just encourage my favorites to make a return performance.
It helps to keep in mind that most of the fancy annuals sold in four-inch pots are either sterile selections propagated from cuttings (so they do not produce fertile seeds), or they are hybrid varieties that will not come true from seed.
I focus my seed-collecting efforts on those annuals designed to flower and produce seed in a single season. Some favorites include sweet alyssum, larkspur, moss rose (Portulaca) and later summer bloomers such as amaranth, spider flower (Cleome), cosmos and black-eyed Susan (Rudbeckia hirta).
Since the very survival of the plant line depends on reseeding success, the next generation is usually easy to grow. In fact, most bloom in response to the day length, so I find that is isn’t really worth starting seed early indoors. They will self-sow in the same area, or seed can be collected, cleaned and sown where you’d like plants to grow next year. You can scatter the seed now, or store in a cool, dry location to scatter in the spring.
Perennials are more complex plants. To ensure long term survival, it is more critical that their seed lands and grows where the plant can take hold and thrive for many seasons, as it may take several years to mature enough to produce flowers. Seeds often require stratification — a fancy term for conditioning that usually includes exposure to a cycle of cold.
That said, seed can be saved from nearly any perennial. Although some are sterile, and others must be propagated from cuttings or division to produce plants that look just like the parents, many more produce good seed. Resulting seedlings may vary wildly, and germination rates are lower than for annuals, but if you have the patience to wait a season or two to see the results, you may end up with something fun and different.
If you want to start the seed indoors in winter to have transplants for spring, you’ll need to do a little research to make sure you’re providing the proper pre-treatment for good germination. Personally, I find that Mother Nature knows best, so I sow seed in fall, in a shallow layer of potting soil on the bottom of a plant flat, and leave it in a protected spot under a tree. Fall rains take care of the water, and seed germinates when it is ready, exposed to the right amount of weather.
The following spring or summer when seedlings are large enough to handle, they can be transplanted to a nursery bed or protected spot in the garden.
I find it most worthwhile to save the seed from annuals that produce large seeds. They can be expensive to buy new, since a packet often contains only four or five seeds. Yet they are very easy to harvest and save from home-grown plants. My favorites are hyacinth bean (Dolichos lablab), scarlet runner beans, and castor beans.
Harvest dried pods now, handling one type at a time to prevent any chance of mixing them up. Keep the largest, robust seeds, and place between layers of paper towel. Tuck into a small zipper lock bag, label, and place in the refrigerator until you’re ready to plant in early spring.
Some easy fall clean up can bring big results next season.