At some point, every gardener has had leftover seeds after sowing the vegetable garden or flowerbed. In addition, saving vegetable and flower seeds is one way to save some money each year (or use that money to feed your gardening habit in other areas).
Saving "store bought" seed is the easiest thing to do. Gardeners typically fold the seed packet over, paperclip or rubber band the seed packets together and put them somewhere until next year. Where you store them can make all the difference in future success. The kitchen junk drawer or garden shed are not good spots. Seeds are alive while stored so the better the storage environment, the higher survival rate you will get. The family refrigerator is going to be the best place. Stored in their original seed packets or a sandwich bag, they should go into a tight sealing container. Tradition suggests a wide mouth-canning jar with ring and a new lid. If you have a lot of seeds to save, maybe two canning jars – one for veggies, one for flowers. The canning jar is "air tight" and slows seed respiration. The temperature in the fridge also slows respiration. This way the seed uses up less energy and saves the rest for germination. A good guideline to remember is the larger the seed, the longer it can be stored. This may help guide you as to what kinds of seed to save. Snap beans are relatively easy while lettuce seed is not.
Before it is time to sow those saved or swapped seeds in the garden or indoors to grow out as a transplant, a germination test is helpful. No matter how well seeds are stored, there will be a reduction in the germination rate. If you look at the seed packet, you will find the germination rate and what year the seed was grown for. Typically, for every year of storage there can be a 10 percent reduction in germination. As mentioned already, very small seeds do not last in storage past one year, and if the seed does, then the germination rate will be substantially reduced. Nothing worse than sowing the garden row or seed flat and having a complete failure. To test, place a sample of seed between moist paper towels, and place that inside a plastic baggy to retain the moisture. Remember, the number of days needed to germinate is on the seed packet. For example, if you have 100 seeds and you test 10, and 8 of them actually sprout, you have an 80% germination rate with the remaining seeds.
If seed swapping is part of your gardening efforts, storing leftover hybrid seed from the packet will guarantee what you share will be true to the variety. Saving seed from the hybrid plant, on the other hand, will not give you that same hybrid again. Open pollenated and heirloom plants do come true to type. With open pollenated plants, the DNA from the female flower dominates. As long as heirloom plants do not get cross- pollinated from a hybrid, they too will come true to type. So, some caution is in order when you receive your swapped seeds. They may be exactly what you wanted or maybe not, depending on how isolated they were during flower pollination. If you would like to try your hand at seed swapping, University of Illinois Extension of Kendall County will be offering a seed swap event on Saturday, February 11, 10 am to noon, at the office, 7775 IL Route 47, Yorkville 60560.
About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.