We all enjoy saving the seeds of our favorite plant or crop. But it is very easy to end up storing too many seeds and not using them in time before they expire.
How long do seeds last?
The longevity of seeds depends on the seed quality, the storage method, and mostly the plant itself. In general, seeds of annuals generally last longer than perennials. Most heirloom seeds can last for 2 to 3 years, some are viable for between 4 to 5 years, and a few for even more than 5 years.
In this article, we will go through a list of common seeds with different shelf life and the best method of storing them for as long as possible.
Seeds storage organizer to keep them from moisture
1. What affects the longevity of seeds?
The longevity of seeds is determined by a number of factors like the type of plant, the seed quality, and how the seed is stored.
1.1 Heirloom vs. GMO?
Technically speaking, seeds from heirloom and GMO plants should have similar life spans. Genetic engineering on GMOs mainly improves diseases, viruses, and insect damage resistance and improves tolerance to herbicides (FDA, 2022).
However, GMOs tend to be less flavorful and nutritious, and some farmers report that the seeds don’t remain viable as long as heirloom seeds do. Still, any differences in life spans are insignificant.
1.2 Annual vs. Perennial
Seed longevity is also affected by the type of plants. The small seeds of annual plants and weedy plants (like clover and nettle) tend to remain viable in the soil for longer periods than the larger seeds of trees and other perennials (Gibson and Gibson, 2006).
It is difficult to declare that seeds of one group of plants like vegetables have a longer lifespan compared to other groups like flowers or herbs. That’s because multiple plants fall under each group, and the different seeds in each group have different life spans.
For instance, vegetable seeds such as onion seeds have a lifespan of about one year. In contrast, vegetable seeds such as cabbage seeds have one of the longest lifespan of over five years.
As such, it’s better to consider seed longevity in terms of annual and perennial plants.
1.3 The initial quality of seeds
Naturally, the quality of seeds will determine how long they last. Healthy plants produce healthy seeds which will remain viable for longer periods than damaged seeds.
The healthiest seeds should be reserved for long-term storage, while average seeds can be kept for the next planting season. Low-quality seeds shouldn’t be stored but discarded as they aren’t viable.
1.4 Storage method
Storage plays a crucial role in the longevity of seeds. Poor storage can greatly reduce the natural life of a seed.
Seeds should be placed in a jar or Ziploc bag that’s air and watertight, then stored in a cool and dry place like a garage or basement. This type of storage can keep the seeds viable for up to two years.
Another way to store seeds is by freezing, and this is the preferred method of most seed banks. Keeping the seeds in freezers will allow the seeds to remain viable as long as possible since the seeds will be kept at a constant temperature, unlike a garage or basement, which may be cool, but still subject to fluctuations in temperature.
2. How long do heirloom seeds last?
The longevity of heirloom seeds depends largely on the plant itself. Most heirloom seeds can last for two to three years. Others like broccoli and cabbage can stay for four to five years, while seeds like lettuce still sprout after five years in storage.
The exceptions are onions and similar alliums which lose viability within one year (Brar et al., 2019).
Here’s a table showing typical life spans of common vegetables and flower seeds.
| Vegetables | Storage years | Flowers | Storage years | |
| Asparagus | 3 | Ageratum | 4 | |
| Arugula | 6 | Amaranthus | 5 | |
| Beet | 4 | Calendula | 5-6 | |
| Brussels sprouts | 5 | Cineraria | 3-4 | |
| Beans | 3 | Digitalis | 2 | |
| Broccoli | 5 | Escholzia | 3 | |
| Celery Cabbage | 3 5 | Gaillardia Godetia | 2-3 3 | |
| Carrot | 3 | Helianthus | 2-3 | |
| Cauliflower Corn | 5 2 | Heliotrope Hollyhock | 1-2 2-3 | |
| Cucumber Eggplant | 5 4-5 | Impatiens Larkspur | 2 1-2 | |
| Kale Kohlrabi | 5 5 | Linaria Linum | 3 1-2 | |
| Lettuce Muskmelon | 6 5 | Lobelia Marigold | 4 2-3 | |
| Okra | 2 | Nasturtium | 5-7 | |
| Onion | 1 | Nicotiana | 4-5 | |
| Parsley Parsnip | 1 1 | Nigella Pansy | 2 2 | |
| Pea Peppers | 3 2 | Petunia Phlox | 2-3 2 | |
| Pumpkins Radishes | 4 5 | Salvia Schizanthus | 1 4-5 | |
| Spinach Squash | 5 4 | Sweet peas Sweet Williams | 2-3 2 | |
| Tomatoes Turnip Watermelon | 4 4 5 | Viola Wallflower Zinnia | 1 4-5 5-6 |
3. What’s the longest seed survival period?
The longest seed survival period on record is about 2000 years, as determined by radiocarbon dating.
The seed was among other seeds preserved in a jar excavated in the mid-1960s from the ruins of a fortress in present-day Israel (Arava Organization, n.d).
In 2005 a group of scientists was able to germinate and grow the seeds by first soaking them in enzymatic water and fertilizer, and then planting them in sterile potting soil.
The first of the seeds to germinate was named “Methuselah” after the oldest man in the Christian Bible. Methuselah will grow to become a male Judean date palm, measuring over 3.5m tall as of February 2020 (Winer and Surkes, 2020).
4. How to check if seeds are still viable?
There are a number of ways you can check if your old seeds are still viable. By simple inspection, you can determine seeds that aren’t likely to germinate. Such seeds will usually be discolored, have holes in them, cracked, and overly wrinkled.
You can also do a water test to check the viability of your seeds.
Fill a bowl with water and put the seeds inside. Some seeds will float, and others will sink to the bottom of the bowl. Seeds that float aren’t viable as they float because they don’t have embryos.
A water test is easy and quick to perform, but the results aren’t very accurate. The best way to test seeds is by a germination test.
– Germination test
A germination test is the most reliable way to check the viability of your stored seeds. The test involves taking a small portion of the stored seeds and placing them in conditions that encourage germination. The number of the selected seeds that germinate indicates the percentage of your remaining stored seeds that are viable.
- Take ten to twenty seeds at random from your seed packet
- Moisten a piece of kitchen paper towel, and place about 5 seeds on it. Space the seeds well so they don’t touch each other
- Cover the seeds with another sheet of moist paper towel.
- Put the covered seeds in a Ziploc bag,
- Place the seeds in a warm area, between 70 and 80 Fahrenheit (20 – 27 Celcius). The top of a refrigerator or a sunny window is a good location.
- Most plants will sprout roots within 10 days. But there are some exceptions like asparagus and parsley that can take weeks to sprout, so check and confirm the germination time for your seeds
- At the end of the germination period, count the number of seeds that germinated and divide by the total number of seeds you tried to germinate.
- A result of 0.7 and above is a good one. It indicates that about 70% or more of your seeds are viable, and will germinate if planted.
- Anything below 0.5 (or 50%) is not a good result and you may need to get new seeds.
5. How to store heirloom seeds
Unlike hybrids, heirloom seeds grow true to type. They would produce the same fruit that they came from, so it’s a good idea to save the seeds for future planting seasons. Here is how to save seeds properly.
- For best results, freshly harvested seeds must be dried before storage, as the moisture in the seeds can encourage bacterial growth that can destroy the seeds. Additionally, moist seeds will germinate before time if temperatures get warm enough.
- You can dry the seeds by spreading them on a flat surface and allowing them to air dry in a cool area. It can take up to 2 weeks until the seeds are properly dried.
- To confirm that the seeds are properly dried, try to bend one. If it appears brittle and breaks, then it is well dried. But if it bends then it isn’t properly dried.
- Place the dried seeds in a paper envelope. The paper will absorb any moisture in case the seeds weren’t well dried.
- Next, put the envelope in a jar or Ziploc bag and seal it. Then store in a cool, dry place until you’re ready to use it. You can also put a desiccant in the jar or bag to further draw out any remaining moisture.
- For longer storage, above two years, put the jar or Ziploc bag in a freezer. You can also put it at the back of the refrigerator, away from temperature changes in the front caused by frequently opening and closing the refrigerator door.
Conclusion
The longevity of heirloom seeds is largely dependent on the plant in question. Most seeds can last for a couple of years, while others like lettuce and cabbage can last more than five years. Onion seeds rarely last more than a year.
Seed longevity can also be affected by other factors like seed quality and storage method. High-quality seeds can store longer than lower-quality seeds. Similarly, proper storage will keep the seeds longer than improper storage.
Happy growing!
Related
Saving Seeds from Green, Unripe Fruits? (We Investigate)
Top 13 Fruits That Grow True To Seed
7 Reasons Why Peat Pots Restrict Root Growth
References
Arava Org. (2020, February 6). Ancient Date Palm. Arava Institute for Environmental Studies.
Winer, S., & Surkes, S. (2020, February 6). Israeli researchers grow new date plants from 2,000-year-old seeds. Times of Israel.
Brar, N. S., Kaushik, P., & Dudi, B. S. (2019, July 25). Assessment of Natural Ageing Related Physio-Biochemical Changes in Onion Seed. MDPI.
FDA. (2022, February 17). How GMO Crops Impact Our World. U.S. Food and Drug Administration.
Page-Mann, P. (2020, January 21). How Long Do Seeds Last? Cornell University.
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