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, …
Will Expired Seeds Still Grow: Planting With Expired Seed Packets
Many people begin gardening not only as a means to grow healthy and nutritious fruits and vegetables, but to also save money. Growing a crop of your favorite vegetables can be an absolute delight, as can herbs and flowers for the garden. However, each season, growers with limited space may find themselves left with unused garden seeds. In many cases, these seeds are stored away for safekeeping, slowly accumulating with what many the gardening community refer to as a “seed stash.” So are old seeds still good for planting or is it better to acquire more? Read on to find out.
Understanding Seed Expiration Dates
If you look on the back of your seed packet, there should be some type of dated information, at least with most reputable sources. For example, it may have a “packed for” date, which is typically when the seeds were packed, not necessarily when they were harvested. As with many items you find at the grocery store, you may have “sell by” or “best by” date, which normally indicates the end of the year those seeds were packed.
Additionally, many seed packages include a “sow by” date, which doesn’t represent the freshness of the seeds but rather the resulting validity of a germination test previously conducted prior to packaging.
While some may wonder whether or not it is safe to plant seeds that have passed their expiration dates, we know that planting expired seeds will not impact the outcome of the final plant grown from that seed. So, will expired seeds grow? Yes. Plants grown from expired seed packets will grow to produce healthy and fruitful harvests, just as their younger counterparts. With this in mind, one may be left to wonder then, when do old seeds expire? More importantly, why do we need seed expiration dates?
Although seeds do not technically “go bad,” expiration dates are used on seed packaging as a measure of the likelihood that the seeds will be viable. Depending upon the type of seeds, environmental conditions, and the manner in which the seeds have been stored, the germination rate of older seed packets may be greatly impacted.
The best storage conditions for seed packets require a dark, dry, and cool location. For this reason, many growers choose to store plant seeds in airtight jars in places such as refrigerators or in cellars or basements. Many may also add rice grains to the jars to discourage the presence of moisture.
While proper storage conditions will help to prolong the lifespan of seeds, the viability of many types of seeds will begin to decline regardless. Some seeds will maintain high germination rates for up to five years but others, such lettuce, will lose vigor as soon as one year in storage.
Are Old Seeds Still Good?
Before planting with expired seed, there are some steps to take to check whether or not germination will be successful. When wondering, “will expired seeds grow,” gardeners can conduct a simple germination test.
To test the viability from a seed packet, simply remove about ten seeds from the packet. Moisten a paper towel and place the seeds into it. Place the damp paper towel into a zip-lock bag. Leave the bag at room temperature for ten days. After ten days, check the germination of the seed. Germination rates of at least 50% indicate a moderately viable packet of seeds.
Growers with limited space may find themselves left with unused garden seeds, stored away for safekeeping, and slowly accumulating into “seed stash.” So are old seeds still good for planting or is it better to acquire more? Click this article to find out.