Long-Term Seed Storage by FarmerIK
To keep seed for many years, it must be protected from heat and moisture. A cool dry area around 50 degrees will keep larger seeds for many years. Cooler temperatures will extend seed life, as long as the seeds are protected from all moisture. That is a problem in a refrigerator with foods in it, or if the door is frequently opened. Moisture from food and room air will be absorbed through paper envelopes and reach the seeds. Many people don’t realize it, but water vapor will move slowly through plastic containers. For long term food storage, thick plastic buckets won’t even keep grain completely dry. Glass, metal, or plastic WITH an aluminum vapor barrier will block all the moisture. Because they are cool and dry, the seeds are dormant. I see some on line sources claim seeds need to be in paper or cloth bags to allow some air exchange. This is simply wrong. Once dry, seeds to be saved for many years should be sealed from any air circulation, because of the moisture it carries.
Small seeds like onions, carrots, dill, lettuce, and parsnips will only keep for a couple years at best.
Our seed collection comes sealed in an aluminum coated vapor barrier bag, with a packet to absorb excess moisture. It will keep years longer because of that. Our collection is safe in your refrigerator or freezer, until you open the outer aluminum bag. If you choose to refrigerate or freeze our seed collection,be sure to take it out, and let it return to room temperature for a couple days before planting.
To store other seeds in ordinary paper envelopes, make sure they are dry. Put them into glass jars with metal lids, such as canning jars. Aluminum coated plastic bags, like the Mylar brand, can also be used. They can be sealed at home with a flat iron.
For really long term storage, a freezer has worked very well for us. The ‘Grampa Neff’ beans we planted in 2007 had been in the freezer for over 20 years, and they grew fine. Make sure the seeds are completely dry, and protected from all moisture. Remember, that means an air tight glass, or metal [including aluminum coated plastic] container.
Carefully stored seeds will last longer, but different kinds of seeds have their own limitations. As a general rule larger seeds keep longer than smaller ones. Corn and beans can last for many years with good storage conditions. Onions and Parsnips are among the ones that won’t last more than a couple years. I have seen many different charts showing how long different seeds will last, but they all come up with different answers. Like nutrition, it is not an exact science. This years advice always seems to contradict last years. It is not just the storage conditions, or even the exact variety, but how it was raised is important too.
If you see a collection of so called Survival seeds, and it includes onions and radishes, you can be sure who ever selected the seeds to include, doesn’t know what they are doing. If the crops are mostly light salad vegetables, what good will that do you when you are really hungry? String beans won’t fill you up either. You need carbohydrates from starchy vegetables and protein from beans and grain. No other grain yields as well, and is as easy to harvest and grow with out machinery as corn.