Solved! Do Seeds Expire?
Everything has a shelf-life, including seeds. Some last longer than others, though, so here’s what to look for and determine if your flower and vegetable seeds may still be viable.
Q: Do seeds expire? I have many flower and vegetable seed packets dating back several years and don’t know if I should keep them or throw them away and buy new seeds.
A: Under ideal storing conditions, your seeds would likely be viable. But nothing is perfect, especially when it comes to providing the requirements to keep seeds happy and capable of germinating from year to year. For that, you need the right combination of humidity, darkness, and cool temperatures. As the temperatures in our homes fluctuate with the seasons, maintaining a “Goldilocks” environment is a challenge, but it’s not impossible. Even when stored under the best conditions, seeds expire. Here’s what you need to know to get the most out of that little seed packet.
Humidity and temperature are critical factors in why seeds go bad.
Seeds have one thing in common: They all deteriorate over time, but some do it more quickly than others. Seeds stored in a warm, humid environment will decline faster than those stored in the darkness where humidity is low, about 10 percent, and the air temperature is between 32 and 41 degrees Fahrenheit.
A lot depends on the seeds’ condition when you place them in storage, and the ultimate kiss of death is moisture. A seed that’s damp when stored will inevitably develop mold and die. A common rule of thumb for an optimal seed storing environment takes the sum of the air temperature in Fahrenheit and the percentage of relative humidity. The total should be less than 100. For most, the refrigerator is the best option. It’s dark, cold, and when stored in an air-tight container like a glass jar, seeds can survive to see another season.
As seeds age, though, their vigor decreases no matter how well you store them. For example, a melon seed that typically has a long shelf life of five to six years may germinate well in its fourth year but produce weak growth and little fruit. In which case, it’s time to pitch the packet and buy new seed.
So, how long do seeds last? It depends on the type.
There is no one-size-fits-all when it comes to estimating seed longevity. And the truth is, no matter how diligent you’ve been about seeing to their every need, seeds eventually peter out. Every seed packet includes a “packaged on date,” which is a good gauge for determining their lifespan. For example, most annual flowers like zinnias or cosmos have a one-year lifespan. The same is true for vegetable seeds like onions and parsnips.
Here’s a list of some of the most common vegetable and herb seeds with their corresponding life expectancy estimates when properly stored.
- Beans, 2 to 4 years
- Carrots, 3 to 4 years
- Sweet Corn, 1 to 3 years
- Cucumber, 3 to 6 years
- Lettuce, 1 to 6 years
- Melon, 3 to 6 years
- Peas, 2 to 4 years
- Peppers, 2 to 5 years
- Pumpkins, 4 to 6 years
- Tomato, 3 to 7 years
- Basil, 3 to 5 years
- Chives, 1 to 3 years
- Cilantro and Dill, 1 to 4 years
- Oregano, 4 years
- Parsley, Rosemary, and Thyme, 1 to 4 years
- Sage, 1 to 3 years
Follow seed storage guidelines to best preserve them.
Not everyone has a refrigerator to store seed, and a shoebox placed randomly on a shelf in the kitchen isn’t the best way to go. So how do you prevent seeds from expiring? Basements and garages are great places. They’re dark and often much colder than the rest of the house during the winter months. If a basement isn’t an option, a closet that shares a wall with the garage, or any other exterior wall, is usually cooler than a closet located on the house’s interior. The most important thing is that the seeds be kept in an area where the temperature remains cool, constant, and dry. The kitchen is hardly the best place.
It’s best to store seeds in air-tight containers, like baby food and mason jars, or anything with a rubber gasket that locks out moisture. For more extensive seed collections stored in envelopes or their original packaging, ammo cans are a great option as they’re air-tight and waterproof. These can be found at most outdoor activity stores that sell hunting, camping, and fishing supplies.
Whether you’ve collected seed from a plant you want to grow again next year or used just a few seeds from a packet and saved the rest, only store dry seed. Moisture is its worst enemy. Just remember, no matter how well you store them, seeds have a mind of their own, and only they know when it’s time to call it quits!
Have you ever thought, "Do seeds expire?" Click here and find out how long vegetable, herb, and flower seeds can last if stored correctly.
Do Seeds Expire and Go Bad?
Part of managing this year’s garden is thinking about next year’s seeds. You may be able to use leftover seeds from this year’s garden in next year’s plan. Or you might be able to save seeds from this year’s harvests. In very general terms, like other living things, seeds can become damaged or diseased and die. The rate at which they lose viability varies by seed type and, most important, storage conditions.
Viability Lore and Science
Legends assert that plants have grown from seeds found in ancient city ruins and royal tombs. Perhaps best known are accounts of lotus seeds found in a Manchurian lake bed, sprouted successfully after 1,200 or more years; in 2002, two Manchurian lotus seeds over 400 years old were grown into mature plants at Brookhaven National Laboratory. According to the U.S. Forest Service, more realistic estimates set the length of time most seeds can remain viable at approximately 150 years. The Kew Royal Botanical Gardens Millenium Seed Bank, a worldwide seed conservancy project, regularly tests many varieties of seeds for viability every five to 10 years. Past and ongoing studies of found seed stashes suggest that numerous members of the bean family (Leguminae; Fabaceae) and grass family (Graminae; Poaceae) may be viable after 40 to 70 years (see References 7, 8 and 9). Not surprisingly, a number of these are commonly regarded as weeds.
Estimating Garden Seed Viability
Scientists classify the lives of seeds as microbiotic, or less than three years; mesobiotic, from three to 15 years; and macrobiotic, 15 years or more, although many factors makes these categories only approximations. Most garden seeds fall into the first two categories; and seeds of plants consumed in their entirety as food, like onions, tend to be the most short-lived. Because of the critical importance of seeds as food sources, home gardeners will likely find more generally accepted information on vegetable seeds than on flowers. Oregon State University Extension, for example, offers only a general guideline for flower seeds, estimating a viability of a year or two for annuals and two to four years for perennial flowers.
Vegetable Seed Viability
A comparison of estimates from two seed producers and two university extensions divided vegetables roughly into three categories. Seeds regarded as viable for one to three years were beans, carrots, corn, leek, onion, parsnip, parsley, spinach, peas and peppers. Those viable for three to five years were beets, brassicas, celery, chard, eggplant, lettuce, cucumber, radish, squash and pumpkin. Generally, tomato, muskmelon and watermelon seeds were considered viable for five to 10 years.
Factors Affecting Viability
In some ways a seed needs to be treated like the plant it will become. Extreme temperatures and excessive moisture are equal threats to seeds. Excess moisture can produce mold or foster fungal diseases and rot in the seeds of most plants that grow in temperate zones (U.S. Department of Agriculture plant hardiness zones 3 through 9), while seeds of plants from subtropical and tropical climate zones (zones 10 and 11) may require high humidity to survive. Cool, dry, dark, clean conditions are necessary to store most temperate-climate seeds, whether purchased from commercial growers or collected from your garden. Keeping seeds in sealed containers prevents mold spores or other airborne organisms from infecting them. Some experienced seed-savers save refrigerator space for winter seed storage. For tropical or non-native plants, information from seed packets, grower sites and botanical gardens can help you provide variety-specific storage for seeds.
For successful seed saving, wait until seeds are fully mature before harvesting them. No matter how carefully stored, immature seeds lack the ability to become new plants. With vegetable seeds, for example, wait until vegetables are slightly past their prime; the seeds of a wrinkled pepper or overripe tomato are mature and ready for storage. Typical seed-packet directions include the length of the typical germination period, usually within 14 days for annuals, and often indicate a soil temperature desirable — and sometimes essential — for germination. Even perfectly viable seeds may not germinate with the wrong soil temperature, water or light. Seeds with very hard outer coverings may benefit from being scraped with a knife blade or sandpaper. Others need the artificial wintering known as cold-stratification, in which seeds spend weeks to months between layers of chilled moist soil or planting medium. Still others germinate faster after being soaked.
Do Seeds Expire and Go Bad?. Part of managing this year’s garden is thinking about next year’s seeds. You may be able to use leftover seeds from this year’s garden in next year’s plan. Or you might be able to save seeds from this year’s harvests. In very general terms, like other living things, …