Timing is key when saving seeds

Lauren Bethke

As fall begins to arrive in Minnesota, it’s a great time to harvest and save seeds to use next year. Saving seeds is a great way to preserve unique plant species, deepen your connection with the natural world, and expand your garden. Read on for tips that will help you collect, clean, and store plant seeds so they will be ready to plant in the spring.
But first, why go to the trouble of saving seeds, rather than simply buying new seed packets in the spring? First, saving your own seed can incrementally improve how plants perform in your garden. By collecting and replanting seeds from successful plants, you help build locally-adapted populations that are more resilient in the long run. Seed saving can also help keep native and heirloom varieties in circulation, which is especially important for less common types of plants.
Additionally, seed saving can make a noticeable difference in the gardening budget. Purchasing packets of native plant seed or heirloom vegetable varieties each spring can add up quickly, especially for larger gardens. By harvesting your own seed at the end of the season, you effectively create a free supply for the following year and eliminate the need to purchase replacements. Many Minnesota gardeners save money each year simply by reusing their own seeds and sharing extras with neighbors or local seed libraries.
There are a number of important things to keep in mind when saving seeds. First, timing is key! Let seeds mature fully before harvesting them. Typically, you should wait until pods are dry and brown, flower heads have fully dried, or fruits are ripe or even overripe. When harvesting seeds from native plants, it’s best to harvest no more than 20% of the seeds on a plant to leave enough for wildlife and natural reseeding.
Then, you will want to clean the seeds and prepare them for long-term storage. The exact technique will depend on the plant, but it’s extremely important to dry out seeds so they don’t grow mold over the winter. Remove any fruit or plant material, then spread seeds on screens, coffee filters, or fine mesh in a cool, dry space with good air circulation. For plants such as tomatoes and cucumbers, where the seeds are inside a sort of gelatinous coating, you will need to ferment them for a few days and then thoroughly rinse them before drying.
Once seeds are clean and dry, you can store them in a cool, dark location. It’s ideal to keep seeds in airtight containers if possible (large glass jars work well), with different types of seeds separated into individual paper packets. Most seeds will remain viable for 2–3 years if properly stored.
If you are saving seeds from vegetable plants, keep in mind that seed saving works best with open-pollinated or heirloom varieties, rather than hybrid varieties. Open-pollinated or heirloom varieties are the result of natural pollination and reflect genetic traits from many generations of plants, so when you save their seeds and re-plant them, the resulting plant is more likely to be similar to the parent plant. Hybrid varieties are created by intentionally crossing two different varieties and combining their traits. Although hybrid plants will generally produce viable seeds, those seeds will combine the genetics of the parent plants in new and unpredictable ways, so the resulting plants may be completely different from what you are expecting.
If this is your first time saving seeds, I would recommend starting small, with just a few varieties. This will allow you to gain experience and learn what works and what doesn’t. And make sure to label your seeds right away so you don’t forget what you harvested! Include the plant type, date, and collection location.
Finally, there are a lot of great local resources for sharing seeds within the community, such as the Como Community Seed Library and the MnSEED Project. Check out these great organizations for opportunities to share and swap seeds to meet your neighbors and expand your collection!
By collecting and saving seeds from native plants and heirloom vegetables, Minnesotans can preserve biodiversity, retain favorite varieties, and carry the lessons of this year’s growing season into the next.
For more information, check out the University of Minnesota Extension Yard and Garden website. Extension resources are written by experts and contain the latest and most reliable research-based information. Happy gardening!